Topic: wiring problem along door sill

[Justin]

I am having a problem. my parking lights in the back dont work and everytime I put a new fuse in and try to see if they work it blows in a spit second. I pulled up my driver door sill and found a mess. Can you tell me what the problem is or what these wires are supposed to go to?

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[Justin]

here are a couple more of the same thing.

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[Justin]

there is an orange wire that just ends right there in that blue clamp thing and a big black wire that ends there also and a smaller brown wire that is also in the same blue clamp and runs back to the trunk. In the other picture there is a pink wire that is in another clamp and onto a brown wire and runs to the back. any ideas or anything at all will help.

[78ta]

Obviously, someone has rewired the car at some point.  The factory used orange for 12v and black for ground. So if there's an orange and a ground together, either that's your problem or someone has added the black wire or both orange and black wires.
The factory orange wire is a 12v wire. Orange is always hot(has voltage) whether the key is on or not. Pretty sure the brown wire is for lighting though grey is also used for lighting and of coarse black is for ground. 
It could be that they added something that isn't even being used any longer like an alarm system or stereo equipment etc so you won't need those added wires. It could also be that some of the factory wiring got damaged and this was their attempt at repairing that.
I assume you don't have a meter. Let us know if you do. It would be easier to troubleshoot if you did. If you don't have a meter, you'll need to go to the store and buy a _bunch_ of fuses.
First, it could be a bulb that is shorted so pull all of the parking light bulbs and try a new fuse with out any bulbs installed. If it does NOT blow, insert the bulbs again one by one and see if one of them blows the fuse. If so, put a new bulb and a new fuse in and try that socket again. If it blows again with a new bulb, one of the wires going to that socket could be shorted to ground. This is where a meter comes in handy. If you don't have one, all you can do is physically trace the wire and try to find a place where the insulation has come off and is touching the metal of the car somewhere. It's not very high tech but tugging on and moving the wires around in general can often resolve the problem if only temporarily by moving the bare wire off the metal it is touching.
If it still blows, with all of the bulbs out, disconnect all of those wires in the blue connectors and try putting the fuse in again. If it does NOT blow, you know you're on the right track and the problem is in the "rewiring" they did. In that case, hook the wires back up one at a time and see if it blows the fuse. If you find that the fuse only blows when a particular wire is connected, trace that wire and see if you can find where the plastic covering has been cut or scraped off and is touching the frame.
PS, check your manual or the fuse block itself and make sure you are installing the correct size(amp) fuse for the circuit.
Didn't you just get this car away from a body shop that you had trouble with? The wiring doesn't look like it was done deliberately does it?
Good luck,

[Justin]

the rewiring was done years ago when the car was painted white before I owned it because overspray is on the wires. I had this problem before the bodyshop. I did the bulb test and it is still blowing fuses. I do not have a meter. The orange wire is not really a wire it is sold under the plastic coating. I will try the other test where I connect just one wire at a time. I NEED MORE FUSES LOL. Im convinced its here that the problem is. after undoing thing blue clip thing all my other electric still works fine so I think the problem is this.

[Justin]

ok so no matter what I do I am still blowing fuses. I cut the plastic tube off of the wires so I can see every wire. I found that it looks like someone just cut a chunk out of two wires and put another piece in there to hopefully keep things flowing. If the big thick black wire is ground should that be ground the the body somewhere? I did try grounding it just to see what happened and it blew the clk fuse. The clock worked fine before without this hooked to anything so Im thinkning whom even did this ground it somewhere else. Now what woud be my best bet? as soon as I turn the key and pul my headlight switch out for my parking lights the fuse blows. I also still have working headlights too.

[Justin]

ok so now that all the wires are exposed I followed everything. Starting from the trunk harness following it up over the back seat down to the door sill. heres what I have. from the trunk I have a white wire that is coming off the harness to an added brown piece that is crimped onto an original pink wire that goes to the fuse box. Second I have an Orange wire coming from the original harness in the trunk with another added brown piece that is crimped to an orange piece that is original and goes to the fuse box.
When I followed these wires to the trunk the pieces that are cut and crimped together look like they go to the dome light part. Dome light doesnt work and Ive never seen it work. Also along with this im going to readd a picture that I had from awhile ago of two wires that are cut at the fuse box and are box dangling there. Im thinking that it goes to dome light and all this is related but can anyone tell me if they know what these wires go to for sure?

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[brian c]

Dome light is Orange and White. It plugs into the bus connector in your trunk. You can unplug it from that harness if you think the dome light is causing the issue or at least eliminate one of the possibilities.

As for a meter...have a Harbor Freight around you? They usually have the nice digital ones on sale for under $10. I've used mine for countless projects now and don't know how I ever got by without one.

Considering you have a hacked rear harness, and brake lights aren't overrated, it might be a good time to just pull out the harness and replace it from one at M&H Wiring Harness (www.wiringharness.com). You might be bottles of advil ahead


**Thinking about it a little more, you mentioned that your dome light has never worked correct? Take out your driver's side door jam switch and see if its shorted. That might point you in the direction you need to be...

[Justin]

would it be the $170 one? Not sure without a pic. Thats really over what I can afford rightnow even though it looks like thats the route I will have to take.

[brian c]

I would think its the $170 one. M&H Tech support is very helpful and they're free. Can very easily tell you what you need.

If your rear wiring is that messed up I'd start from scratch.

**And its a lot better than the $625 dash harness!

[Justin]

well. I went out and bought a new harness today locally. NO MORE CUT WIRES.YAY!!!!but im still blowing the same fuses.its not the bulbs it not the wiring harness. any other ideas what else it could be? Is there more then one funtion for this fuses and is just not being gounded somewhere else? when you pull the headlight switch out it turns the parking lights on right? what all should be working when I pull the switch out? is there a relay im missing or something?

[ta78w72]

You've got a dead short somewhere.  I'd check the trunk wiring first because it's easy to access.  Disconnect the connector running from the IP harness in the trunk and check each trunk wire with an ohm meter.  One lead on the wire in the harness and the other to the body.  Then give us a list of which wires seemed to be happy grounded.  Usually black wires are ground, white wires are switched ground and that pesky brown wire is grounded when the headlights are off.  The Brown wire may not ground since you've disconnected it at the connector.

The parking lights...the brown wire provides ground to the side marker lights for the blinkers when the lights are off.  When you turn the parking lights on, you get 12 volts to the parking lights and the side marker lights via that brown wire.  When you turn your blinker on with the parking lights on, the parking lights and the side marker lights will blink alternately.  That's because the flasher goes from 12+ to ground.  The parking lights will blink with 12+ from the flasher but the side marker lights will go out because both the brown and flasher wire are 12 +.  When the parking lights are off and the blinkers are turned on, the blinker wires get 12+ - ground 12+ etc.  They will both blink in unison because they both depend on the flasher for voltage.  When the headlights are on, the brown wire is continuously 12 +.  So the side marker lights will get 12+ on both wires....no light, but when the flasher grounds.....the side marker will use the 12 + from the brown wire and ground through the flasher for the other....it goes on.

See, blinkers are easy   It took me a good while to figure them out.

Try disconnecting the harness at the trunk and turning your lights on to see if you blow a fuse.

[Justin]

ok. So I disconnected the harness in the trunk and still blow a fuse. I diconnect the harness at the fuse box and still blow a fuse. Can it be a bad headlight switch? maybe the harness from the switch to the fuse box. I am learning from all this though so thats a good thing.

[78ta]

In your first post, you said in part "my parking lights in the back dont work". Does this mean that the front parking lights work? I don't see how that would be possible.

I'm not sure if the Trans Am works the same way but the under hood light on my 70 442 only has power to it when the parking lights are on. You might check that out. I can't get to my TA just now or I would check it. Raise your hood and see if the under hood light comes on with OUT the parking lights on. Make sure the bulb is good. If it does, it's on another circuit from the parking lights and not part of the problem.
If the under hood light never comes on, parking light switch pulled or not, it or the wiring to it could be involved. Someone will have to jump in and confirm it's operation regarding whether the parking light switch has to be on. I'll check as soon as I can and post back if no one else does.
It sounds like you've got a good handle on the method of troubleshooting electrical circuits given your responses about disconnecting harnesses to eliminate them etc. A lot of it is just a process of elimination but it often comes down to checking for open wires or shorts to ground which requires a meter. I think you'd get a lot of benefit from investing in a cheap $10 meter. 

[Justin]

well. I went out and bought a new harness today locally. NO MORE CUT WIRES.YAY!!!!but im still blowing the same fuses.its not the bulbs it not the wiring harness. any other ideas what else it could be? Is there more then one funtion for this fuses and is just not being gounded somewhere else? when you pull the headlight switch out it turns the parking lights on right? what all should be working when I pull the switch out? is there a relay im missing or something?

   AS I asked in one of my questions/responses,I am not sure what all should be on when I pull the parkinglight/head light switch. Are there lights in the front or side that are supposed to be on? I dont see an under hood light source at all. If there are lights in the front I can try and rule those out but like I said I am not sure what is all supposed to be on when I pull the switch.