Topic: need help w/ testing printed circuit on Instrument cluster

[Eagle 1]

Did you click on this link too?  http://www.firebirdtransamparts.com/techinfo/harness/optionwire/optionwire.htm

Yea if you dont have the manual from Brett, you need to get one.

[ta78w72]

That helps a little.  I really need that service manual.  I think I'm just going to get the radio and equalizer out of the way.  There are so many grey speaker wires back there, it's hard to work.  The old speaker wires are nowhere to be found.  The grey, yellow, and black wires that are tied together have to be the old stereo wires.  Everything else is going somewhere.

If I get an original radio now for this car, will I need the connectors that were once on the harness? or can the wires be directly connected? 

The speaker wires aren't part of the dash harness.  When they changed the stereo, they probably changed the speakers and toss the speaker wires and connectors into the original radio.

I would guess that the yellow, gray and black wires would be from the old radio connector from the dash harness.  A simple way to test is....yellow is switched power....when you turn the key on.  Gray is hot when you turn the dash lights on.  Black is ground.

[HotBird]

Did you click on this link too?  http://www.firebirdtransamparts.com/techinfo/harness/optionwire/optionwire.htm

Yea if you dont have the manual from Brett, you need to get one.

yea...I clicked on that link too.  It helps me understand the setup a little more until I can get my hands on that service manual.  But in the photos on that link, the stereo wires coming out of the harness are different colors than what I'm seeing.  i know the grey speaker wires aren't connected to the harness....the other owner just did a horrible job connecting them and left so much excess wire, it's hard to move around them working on the rest.  I need to get rid of those speaker wires and start from scratch.  I want the original radio anyway which only gives output to two speakers, correct?

[HotBird]

That helps a little.  I really need that service manual.  I think I'm just going to get the radio and equalizer out of the way.  There are so many grey speaker wires back there, it's hard to work.  The old speaker wires are nowhere to be found.  The grey, yellow, and black wires that are tied together have to be the old stereo wires.  Everything else is going somewhere.

If I get an original radio now for this car, will I need the connectors that were once on the harness? or can the wires be directly connected? 

The speaker wires aren't part of the dash harness.  When they changed the stereo, they probably changed the speakers and toss the speaker wires and connectors into the original radio.

I would guess that the yellow, gray and black wires would be from the old radio connector from the dash harness.  A simple way to test is....yellow is switched power....when you turn the key on.  Gray is hot when you turn the dash lights on.  Black is ground.

My next question is how would i test the yellow for switched power?  Ya know, these wires were hanging there unattached.  A few months ago when I saw my parking lights staying on, I stuck my hand under the dash to try and feel for any loose wires and some hot wire touched the back of my hand...but I couldn't see what wire.  It just might have been that gray one.

[Eagle 1]

You need a multimeter or a test light to check the yellow wire for power.  It should power up when you turn on the ignition switch.
They grey wires will have power when you turn on the headlights.
Like ta78w72 said there are no factory speaker wires in the wiring harness.

[ta78w72]

Actually, the original radio will power two front speakers and two rear speakers.  That's what I have in my car.  I have two rear speakers....one on each side of the package tray, and two front speakers.  I used a speaker set from Classic that fits in the middle slot of a 78 but has two speakers.  You'll need to find the connector set on ebay.  They sell them all the time.  You need the black connector, blue connector and white connector.  They are very specific because they only fit in the radio a particular way...each in their own slot.

As far as your pictures above....the orange wire and brown wire in the black connector....that's for a digital clock that wasn't used.  That just hangs.

I think the other one is for a key minder buzzer.  That should be an orange/black wire and a black/pink wire.  It's hard to tell from the picture if that black wire has pink on it.


By the way, the original radio will power a power antenna.  The black connector has an open slot...that's for switched power.  That deploys the antenna.  Then you need another wire from the fuse box to the antenna with always on power...that brings the antenna down when you turn off the engine and pull the key.  I've been through all this and had to figure all this stuff out.

By the way....you're getting close to owing me a beer!

[HotBird]

Actually, the original radio will power two front speakers and two rear speakers.  That's what I have in my car.  I have two rear speakers....one on each side of the package tray, and two front speakers.  I used a speaker set from Classic that fits in the middle slot of a 78 but has two speakers.  You'll need to find the connector set on ebay.  They sell them all the time.  You need the black connector, blue connector and white connector.  They are very specific because they only fit in the radio a particular way...each in their own slot.

As far as your pictures above....the orange wire and brown wire in the black connector....that's for a digital clock that wasn't used.  That just hangs.

I think the other one is for a key minder buzzer.  That should be an orange/black wire and a black/pink wire.  It's hard to tell from the picture if that black wire has pink on it.


By the way, the original radio will power a power antenna.  The black connector has an open slot...that's for switched power.  That deploys the antenna.  Then you need another wire from the fuse box to the antenna with always on power...that brings the antenna down when you turn off the engine and pull the key.  I've been through all this and had to figure all this stuff out.

By the way....you're getting close to owing me a beer!

I didn't know these cars had power antennas.  After checking out that harness link yesterday, I looked on ebay for the stereo connectors.  I'll look at that front speaker set from Classic.  Thanks for your help!

 A beer is definetly in order!!

You need a multimeter or a test light to check the yellow wire for power.  It should power up when you turn on the ignition switch.
They grey wires will have power when you turn on the headlights.
Like ta78w72 said there are no factory speaker wires in the wiring harness.

I have no experience with using a multimeter.  I know it's simple but I'm still learning.  I'll test those wires this weekend.  I know the speaker wires don't go to the harness.  The speaker wires he put in, however, were just all over the place...bundled up, split and then split again.  The back speaker wires were even worse.  It was so unnessicarily confusing, I'd have to draw his setup to explain it!  I mean, speaker wires are simple...but he had both rear speaker wires crossed with each other TWICE!  What was he thinking?...

[ta78w72]

These cars didn't have power antenna's...at least in 1978.  They did in 1979 though.  But the radio was made for a lot of different 78 models....some probably had power antenna's. 

[HotBird]

ahhhhh.  Got it.

[Eagle 1]

I added two speakers in the front as well but I replaced the kitt speakers with a pair of 4" Alpines.
Here are some pictures.  http://www.78ta.com/smf/index.php?topic=4022.60

[HotBird]

Well, I haven't cut any wires, or removed any that wasn't necessary to remove the dash.  i unplugged everything like the heater, gauge cluster, fuel/volt.

I plugged the light switch back in to try and test the wires, but now the courtesy lights don't come on.  The headlights do, but no courtesy.  i reattached the black ground under the dash, but still no courtesy.  Does something else need to be connected to get my courtesy light circuit closed? 

Also, to test those three wires (black, gray, yellow) that are coming out of the harness to see if they are the stereo wires (hot, switched hot, and ground), does the key have to be in the ignition, or is just having the battery hooked up enough to test the wires?  is this clear to anyone?

[HotBird]

I'm ordering the service manual from Hitman today or tomorrow. I'm just eager to work on this now.

[ta78w72]

The courtesy lights don't work off that black ground wire.  There's two wires that work those lights.  An orange wire that's always hot.  That is, if you measure the current with the volt meter you'll always get 12 volts.  All those orange wires work that way....courtesy lights, power trunk release, map lights, glove box light, etc.  At rest with the door closed, the circuit is broken because there is no ground.  When you open a door, the door switch is really a ground point.  When the door opens, the switch opens and grounds the circuit.  That's the white wire.  The white wire is switched ground.

So, even though you grounded that black wire, it has no being on the courtesy lights.  Perhaps one of the connectors you unplugged compromised the courtesy light circuit....either you haven't connected the orange wire, or the white wire is not properly connected.

[HotBird]

oh...i bet i know the problem.  i have to reconnect the door switch to the floor courtesy lights.

[ta78w72]

There you go!