Hitman's Pontiac Trans Am Forum
Trans Am Information => Trans Am Tech => Electrical => Topic started by: rkellerjr on January 05, 2008, 11:43:10 AM
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Seems that my front running lights aren't working. I have headlights, turn signals, emergency flashers, all tailight functionality works fine as well. This is isolated to just the running lights on the front of my '75. Now, recently I exchanged my engine harness and prior to that everything was fine. What I don't remember is whether the lights were fine RIGHT after the install or shortly after the install. So far, here's what I've done...
* Checked fuses, had one blown but no effect
* Pulled the harness block from the firewall, checked all pins, everything is fine, reinstalled and made sure it was secure.
* Shaked the front harness wires to see if maybe I had a short.
Now, this includes both lights in the grill and the side markers. Thoughts?
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Have you checked the switch? I don't have a 75 wiring diagram but on the 78 it's one of the brown wires that carries current to the headlights. Also, check your ground wires.
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Forgot to mention that I did check the ground wire for the harness, it's intact but, I would think that would cause all lights to fail, not just the running lights.
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I misread your post. Now that I've reread it, I don't have a clue what you're talking about. I don't know what "running lights" are. Are you talking about the parking lights which are also the turn indicator lights?
You said you have turn indicator lights? The turn indicator lights including the ones in the front grill and side markers. Do they work when you turn the signals on?
Do the parking lights and side marker lights come on with the first position of the headlight switch? Do they come on with the second position of the headlight switch? Are they always "Dead".
Those parking lights are grounded and my guess is the side marker lights get their ground from them too. Try running a ground wire from the parking light to the frame and see if the lights work.
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Check the bulbs in the side markers. The front marker lights are wired a little weird in order to get the side lights to come on with the markers and flash with the turn signals while only having one element. If they are burned out it will play games with the other lights. For that matter so will any of the marker lights being bad or a bad ground. But those small bulbs would be my first thing I'd check.
Here's a wiring diagram.
http://www.autozone.com/images/cds/gif/large/0900823d8021731c.gif
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Running lights, parking lights, same thing. The parking lights will not come on and that includes the side markers however, as I've mentioned ALL turn signals work as well as the hazard. Which means that the parking light bulbs are flashing and the side marker bulbs are flashing. Here's a vid, first I turn on the parking lights, then the headlights, then the turn signals, then the hazaards, then turn off the headlights with just parking lights, then off.
http://www.zenonline.com/~rkeller/2007vids/ParkingLights.wmv
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Check the bulbs - it's probably one or two. Even though they may all blink, there is 'sposed to be a low intensity glow with just the parking lamps. When my I turn on the parking lamps and hit the turn indicator on my '76, they come on brighter but the parking lamp intensity remains.
I also seem to recall a situation in years past where there'd be one on, burning a bit brighter, but they wouldn't blink.
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Check the brown wire for 12 volt. That's the circuit that's controlled by the switch. The other circuits, the blinking, is done with the turn signal. When you pull the headlight switch out to the first position, you should get those lights on. Then the second position turns on the headlights so that both sets of lights are on.
How about the rear side marker lights, do those come on? It certainly isn't the bulbs. Unless all of them are bad....that would be six bulbs if the rear doesn't come on. Doubtful.
That leads me back to the brown wire. You have a complete circuit when you're in the blinker phase, but no circuit when the headlight switch is pulled on. That would suggest to me that you're not getting current down the brown wire....and if you're not getting the rear side marker lights on, it's my only guess.
See, you get current from two different sources, the blinker circuit and the headlight circuit. The blue wires are for the blinker circuit. I assume you get ground for both circuits off the black wire from the parking light. But checking the brown wire is the first step, with the second step to ground the parking lights.
If you're not getting 12 volt down the brown wire, you need to pull the switch and check it with an ohm meter.
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Rich is really getting into the video thing. ;) That does help though. You're right, a bad ground would most likely cause issues with the t/s circuit as well.
Ok, according to the wiring diagram all the marker lights, front, back, sides and lic. plate are all controlled by the brown wire from the headlight switch. At some point either under the dash or right at the bulkhead connector (I don't remember exactly where) it splits to go either to the nose or tail of the car. (Someone refresh my memory. I seem to recall some cars with a pair of wires coming off the same connector at the headlight switch also.) So we know it's ok up to that point. So the problem is in that wire up to the nose where it begins to split up to each individual bulb. Either in a connector or a break in the wire.
Have you been able to check for power at the lights or bulkhead connector?
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There's a double brown on the interior section of the bulkhead connector. There's another splice in the engine compartment to feed the four lights. If the rear lights don't come on, it's most likely a bad switch, at least that's where I would start. If the back side markers do come on, I'd start looking at the front light grounds, because the rear side marker lights are each grounded.
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There's a double brown on the interior section of the bulkhead connector. There's another splice in the engine compartment to feed the four lights. If the rear lights don't come on, it's most likely a bad switch, at least that's where I would start. If the back side markers do come on, I'd start looking at the front light grounds, because the rear side marker lights are each grounded.
Wouldn't the front turn signals share the same ground as the front marker lights? Especially since they share the same 1157 bulbs?
He did mention in the first post that all his taillights are working.
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Rear lights work fine. ALL lights on the car work as advertised EXCEPT the front parking lights. I do not think it's a bad switch however, I do have a brand new switch, I've just never installed it. I couldn't figure out how to get the switch out of the dash after taking the bezel off.
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Then we're back to ground....assuming you have the brown wire on the engine compartment side in the right slot so it connects to the proper spot on the interior bulkhead connector.
The rear lights working tell me that you've got 12 volt to the interior bulkhead connector (and that your switch is OK). So, try grounding one of the parking lights and see what happens. If still nothing, pull the engine compartment side of the bulkhead connector and check for 12 volts at the interior connector (which you should have if the rear side marker lights go on). If you've got voltage, ensure that you've got the wire in the right slot. Reinstall and check for voltage. If you've got voltage, check for voltage at the brown wire of the parking light, if you've got voltage...you have a bad ground. If you don't have voltage, those brown wires are spliced together.
At this point, I can only see two possibilities....a bad ground to both parking lights, or a wire in the wrong slot of the engine compartment bulkhead connector. Get your volt meter out.
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Rear lights work fine. ALL lights on the car work as advertised EXCEPT the front parking lights. I do not think it's a bad switch however, I do have a brand new switch, I've just never installed it. I couldn't figure out how to get the switch out of the dash after taking the bezel off.
Not really true...your front side marker lights aren't working right?
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When I say parking lights I mean all of the orange lights that should be on in the front, which includes the side markers and your right, they are not working as "parking" lights, just as turn signals.
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Rear lights work fine. ALL lights on the car work as advertised EXCEPT the front parking lights. I do not think it's a bad switch however, I do have a brand new switch, I've just never installed it. I couldn't figure out how to get the switch out of the dash after taking the bezel off.
Not really true...your front side marker lights aren't working right?
Marker lights / parking lights / clearance lights - basicly the same thing with different names depending on where in the country/world you're standing. Suffice it to say he has 4 bulds that aren't coming on with the taillights as they should be. Two of those bulbs are dual filiment types with the 2nd filiment being used by the turn signals. Those turn signals share the same ground(s) as the first filiment. One is working and the other is not. That's why I was asking - if the ground was bad wouldn't it affect the turn signals as well?
The other two bulbs are single filiment types and are not grounded directly to the chassis but rather back through the circuit which is linked back to the turn signals allowing for them to flash or not depending on the specific posision of the switches.
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Rich -- your turn signals aren't working the way mine do. On my car (and, IIRC, all the other cars I've had) when the headlights are on the front turn signal and the side marker light ALTERNATE flashing, i.e., when one is lit the other is off. Only when the headlights are off do they both turn on at the same time.
Dunno what that means...but it's something different about how your car is working than my car does... :-\ :-\
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Rich -- your turn signals aren't working the way mine do. On my car (and, IIRC, all the other cars I've had) when the headlights are on the front turn signal and the side marker light ALTERNATE flashing, i.e., when one is lit the other is off. Only when the headlights are off do they both turn on at the same time.
Dunno what that means...but it's something different about how your car is working than my car does... :-\ :-\
That indicates that the side markers aren't getting power from the brown wire.
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There's a double brown on the interior section of the bulkhead connector. There's another splice in the engine compartment to feed the four lights. If the rear lights don't come on, it's most likely a bad switch, at least that's where I would start. If the back side markers do come on, I'd start looking at the front light grounds, because the rear side marker lights are each grounded.
Wouldn't the front turn signals share the same ground as the front marker lights? Especially since they share the same 1157 bulbs?
He did mention in the first post that all his taillights are working.
OK, first taillights are different from side marker lights. We are trying to solve a problem looking at a computer screen. We all need to write clearly and describe what we are trying to convey with the proper terminology. Whether or not the rear side marker lights are working is a key element in determining what exactly is wrong. Saying the taillights work isn't enough. That's why I asked the question. It's kind of similar to that comment "My car won't start". What the heck do you do with that but ask more questions? It's also like the recent thread about pinging. He described it as clatter which would indicated to me something mechanical...and I think you did too Larry. So, pardon me for nit picking...but I asked those questions for clarity so I could drill down on the problem.
As far as the ground for the turn signal indicators, I'm not exactly sure where that circuit gets its ground. You could be correct in that the ground is obtained at the parking lights. But that circuit is also grounded at the IP harness.
There are only two wires to contend with. I wanted him to eliminate ground as an issue first since that's relatively simple to do. If he has ground, it's the brown wire at some point. Since both the parking lights and side marker lights aren't working, it's either at the splice where they bunch out, or at the bulkhead connector. As I said, above at this point I'd put my money on the wrong slot in the bulkhead connector. But, I didn't do the hands on work and I can only guess at what's more probable.
If this post sounds abrupt, it's not my intention. I'm only trying to help Rich solve his problem.
By the way Rich, that car is beautiful.
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I'm sorry, but it just seems like the same question is being asked and answered several times but not being interpretted the same way or soemthing. Just like when I said the front turn signals share the ground with the front marker lights. I never mentioned the turn signal indicators. I was talking about the lights in the grills. The turn signals and the front marker lights are the same bulbs. Probably 1157s. If the ground for the maarker light in the grill was bad - wouldn't it affect the turn signal in the grill as well since it uses the same light bulb? One light bulb woudn't normally use different grounds for each filiment.
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Since both the parking lights and side marker lights aren't working, it's either at the splice where they bunch out, or at the bulkhead connector.
I think that may be what's confusing things. The bulbs are working -- they are lighting up, but NOT when the headlights are on. When the headlights are on THEN they will flash but aren't "on" (as in lit) when they are NOT flashing.
Is that right, Rich? :-\ :-\
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Since both the parking lights and side marker lights aren't working, it's either at the splice where they bunch out, or at the bulkhead connector.
I think that may be what's confusing things. The bulbs are working -- they are lighting up, but NOT when the headlights are on. When the headlights are on THEN they will flash but aren't "on" (as in lit) when they are NOT flashing.
No, the parking lights are not working nor are the side marker lights. That shouldn't confuse things because as I described it there are two different circuits controlling the features of those bulbs. The blue wires provide power for the flashing, while the brown wire controls the function when you pull the headlight knob marker lights together. They're different in my mind. I can see how people could use the terms together but I wanted to be precise so I could try to determine exactly what was going on.
Is that right, Rich? :-\ :-\
I never once mentioned bulbs except to say they weren't the problem. I consistently pointed to either the switch, brown wire or ground. When I found out that the rear side marker lights and taillights were working I ruled out the switch and figured the wires at the interior bulkhead connector were OK. That left ground, the wires at the engine compartment connector (either not connecting properly with the interior connector, or in the wrong engine compartment slot), or where the brown wires splice out to the four lights. Simple enough.
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Oh boy, I thought my video would help explain things. Let me try again...
1) All turn signals, in the grill, side markers, rear signals, rear markers, all lights that blink are blinking when the turn signals are turned on.
2) Break lights work
3) Reverse lights work
4) When I turn on the parking lights via the cabin headlight switch (not the headlights!) the front grill lights and the front markers do NOT come on, the rear lights and markers DO come on, they work fine.
5) When I turn on the turn signals (no matter what the headlight switch is set to) all front, rear and markers blink fine.
6) When I turn on the hazards (no matter what the headlight switch is set to) all front, rear and markers blink fine.
7) Turning on the headlights has not effect on the above and the headlights work fine.
Does this clarify what's happening?
Now, there is a ground coming out of the light harness, it's hooked to a screw near the battery. I can unhook it and clean it, splice a piece of new wire and see if that fixes the problem.
The block on the firewall contains two blocks put together, the engine harness block and the front light harness block. The go together so that there isn't any way that I can plug it into the wrong circuit. It fits right into a block that guides it in also.
Rick, I've never "looked" at how the blinkers blinked in the past, I'd say they should be blinking like yours and that may be an indicator as to what might be wrong. Thoughts?
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The block on the firewall contains two blocks put together, the engine harness block and the front light harness block. The go together so that there isn't any way that I can plug it into the wrong circuit. It fits right into a block that guides it in also.
Is that the original harness that came with the car or a replacement? If it's a replacement, you've got to make sure the right wires from the exterior block comes into contact with the right wires from the interior block. If it's the original, you've got to make sure that the terminals have the proper integrity and couple together correctly. That's why you've got to get out your volt meter. Otherwise, you'll never figure out what's going on.
The video did explain quite a bit. It was worth putting up. It made it obvious that it wasn't the bulbs.
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The block on the firewall contains two blocks put together, the engine harness block and the front light harness block. The go together so that there isn't any way that I can plug it into the wrong circuit. It fits right into a block that guides it in also.
Is that the original harness that came with the car or a replacement? If it's a replacement, you've got to make sure the right wires from the exterior block comes into contact with the right wires from the interior block. If it's the original, you've got to make sure that the terminals have the proper integrity and couple together correctly. That's why you've got to get out your volt meter. Otherwise, you'll never figure out what's going on.
The video did explain quite a bit. It was worth putting up. It made it obvious that it wasn't the bulbs.
I do remember that he only replaced the engine harness, not this one. However that doesn't mean that the connection is as good as it needs to be. I think that you and I are both right with the brown wire. The next step is to check that wire with a volt/ohm meter. As bad as the engine harness was I can't imagine that the light harness is without problems.
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The block on the firewall contains two blocks put together, the engine harness block and the front light harness block. The go together so that there isn't any way that I can plug it into the wrong circuit. It fits right into a block that guides it in also.
Is that the original harness that came with the car or a replacement? If it's a replacement, you've got to make sure the right wires from the exterior block comes into contact with the right wires from the interior block. If it's the original, you've got to make sure that the terminals have the proper integrity and couple together correctly. That's why you've got to get out your volt meter. Otherwise, you'll never figure out what's going on.
The video did explain quite a bit. It was worth putting up. It made it obvious that it wasn't the bulbs.
I do remember that he only replaced the engine harness, not this one. However that doesn't mean that the connection is as good as it needs to be. I think that you and I are both right with the brown wire. The next step is to check that wire with a volt/ohm meter. As bad as the engine harness was I can't imagine that the light harness is without problems.
I also wonder how long its been this way. You're 100% correct. The volt meter will give him the answer.
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The block on the firewall contains two blocks put together, the engine harness block and the front light harness block. The go together so that there isn't any way that I can plug it into the wrong circuit. It fits right into a block that guides it in also.
Is that the original harness that came with the car or a replacement? If it's a replacement, you've got to make sure the right wires from the exterior block comes into contact with the right wires from the interior block. If it's the original, you've got to make sure that the terminals have the proper integrity and couple together correctly. That's why you've got to get out your volt meter. Otherwise, you'll never figure out what's going on.
The video did explain quite a bit. It was worth putting up. It made it obvious that it wasn't the bulbs.
I do remember that he only replaced the engine harness, not this one. However that doesn't mean that the connection is as good as it needs to be. I think that you and I are both right with the brown wire. The next step is to check that wire with a volt/ohm meter. As bad as the engine harness was I can't imagine that the light harness is without problems.
I also wonder how long its been this way. You're 100% correct. The volt meter will give him the answer.
Good point. Rich, you said you don't remember them working immediately after you replaced the engine harness. Do you remember them working just before you did?
Edit: just reread your initial post one more time and see that you said they were working then.
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Correct, all light functions worked perfectly until the engine harness install. What I don't remember is if they worked "right after" the install or not. It just didn't dawn on me to check them as they were working fine. I'll get my volt meter out and do some checking, hopefully tomorrow. Now, I assume I'm to pull the bulb out and check there correct?
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Rick, I've never "looked" at how the blinkers blinked in the past, I'd say they should be blinking like yours and that may be an indicator as to what might be wrong. Thoughts?
Correct. I've never had any problems with mine, and it's never been apart, so at this point I'm going to assume that's the way they all should have worked.
NOTE: I didn't mean anything when I said it wasn't the bulbs -- I was just trying to clarify that it's something about how they're working that is the problem. I'm guessing it's something like you guys are describing, and THE clue to that is to be found in why Rich's lights don't work like mine. ??? ???
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I'm going to re-do that ground coming from the harness first and see what happens. Then I'll volt meter stuff, weeeeee
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Hey Rick, 75fire, over at TAC, indicates that the marker and grill light blink at the same time.
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I'm going to re-do that ground coming from the harness first and see what happens. Then I'll volt meter stuff, weeeeee
Don't redo the ground. Check it with your volt meter first. If you "redo the ground" you're not really isolating the problem...that's more like parts changing. To check the ground, if you can stick a small wire into the connector for the parking lights at the black wire....then attach one of your ohm meter leads to it and the other to the frame....see if you've got a completed circuit. If you do, and I suspect you will, then move on to the brown wire of the bulkhead connector and measure for 12 volts. I do suspect the brown wire. I'm anal when it comes to ground though...I always check and I always suspect ground.
Good luck!
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Hey Rick, 75fire, over at TAC, indicates that the marker and grill light blink at the same time.
Hey Rick, 75fire, over at TAC, indicates that the marker and grill light blink at the same time.
They have to blink at the same time because they are on the same circuit.
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OK -- something's getting lost in all the words, like ta78w72 says...
Here's a pair of videos to illustrate what I'm trying to say...
Headlghts OFF...
(http://i54.photobucket.com/albums/g105/TACRick/75%20TA/th_100_3052.jpg) (http://s54.photobucket.com/albums/g105/TACRick/75%20TA/?action=view¤t=100_3052.flv)
Headlights ON...
(http://i54.photobucket.com/albums/g105/TACRick/75%20TA/th_100_3053.jpg) (http://s54.photobucket.com/albums/g105/TACRick/75%20TA/?action=view¤t=100_3053.flv)
The differences are (a) with the headlights OFF, the lights blink in synchronization, and (b) with the headlights ON, the front turn signal bulb is dimly lit and blinks brighter ALTERNATELY with the side marker light.
Do the vids show that? I hope so -- lotta jacking around to show it... :-\ :-\
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Rick,
See, you learn something new all the time about these cars! I never really noticed that before. I checked my car and it does the same thing. Which indicates that the brown circuit is out of whack on Rich's car.
I have no idea why it works that way though. The blue wire from the blinker circuit is shared by both those lights. I guess I'll have to look at my spare harness one of these days to really understand what's going on.
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OK, now we are getting somewhere. With my headlights on, they are blinking at the same time, whicih they should blink alternating.
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HOORAY! Success in communicating!
Actually, I think *if* we can figure out WHY that's not happening on Rich's car the problem will be pretty simple to fix. ;)
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The reason the front bulb is dim then bright in the 2nd vid is because it has two filiments. The dimmer of the two is the parking light fed by the brown wire.
Ok, I hope this helps to explain how they work.
Here is a modified copy of the Autozone wiring diagram.
(http://i20.photobucket.com/albums/b230/SirLDragon/FrtHLTSCircuit.jpg)
I simplified it to show only what we are talking about. I also colored the wires to make it a little clearer.
In some ways we are talking about 4 circuits here even though there are only 2 pairs of bulbs and only 3 pairs of filiments.
In the grill we have a single pair of bulbs, but they each have 2 filiments. A dim one for the parking lights and a brighter one for the turn signals.
- The bright side gets power from the fuse box, through the flasher, through the t/s switch in the column and then through the blue wires to the bulb then directly to ground at a point near the bulb on the core support. Pretty straight forward circuit.
- The dim parking light filiment gets it's power from the headllight switch, through the bulkhead connector, down the brown wire to the bulb and then to the same ground as the t/s side. Also (and even more so) very basic.
Then there's the side markers. Here's where it gets a little weird since, as you can see in the diagram they have no visible ground. This is where most people get turned around.
- When the headlights are off and you use the turn signals they are pretty simple. Power comes through the blue wires to the bulbs just like for the front. The ground is actually in the headlight circuit.
- When the headlights are on and the turn signals are off they are also pretty simple. Power from the headlight switch comes down the brown wire to the bulb. But now the current is flowing the other direction and the ground is in the turn signal circuit. (I've heard different oppinions as to exactly where but for this particular problem that's not really important.)
- Now - when you have the headlights and the turn signals on at the same time this is what happens. Like before, the marker light power is coming through the brown wire making that hot rather than a ground. When the flasher sends power through the blue wire that side also becomes hot, interupting the ground on that side. This causes the bulb to go out until the flasher opens and the t/s side becomes the ground again. This makes the bulb flash opposite to the front turn signal.
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Thank you Larry, that was very helpful. I found out what the problem was and it's fixed. Everything working appropriately. The brown wire receptor in the fuse box was not making a good contact. I may have bent it slightly or something but, I played around with it and then put the block back on and everything worked just fine.
Thanks everyone for your help!
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Nice! Glad to hear you didn't have to rewire the whole circuit.
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Just in case they fail again. Here's something you can use. Just hold this up in your window so people know what it should look like. ;)
(http://i20.photobucket.com/albums/b230/SirLDragon/Cars/RichsTurnSignals.gif)
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hehehehe!
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Show off... ;D ;)
Just in case they fail again. Here's something you can use. Just hold this up in your window so people know what it should look like. ;)
(http://i20.photobucket.com/albums/b230/SirLDragon/Cars/RichsTurnSignals.gif)
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Check the brown wire for 12 volt. That's the circuit that's controlled by the switch. The other circuits, the blinking, is done with the turn signal. When you pull the headlight switch out to the first position, you should get those lights on. Then the second position turns on the headlights so that both sets of lights are on.
The video did explain quite a bit. It was worth putting up. It made it obvious that it wasn't the bulbs.
Good work ta78w72. ;)