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

[HotBird]

Can anybody help with my printed circuit on my 78 TA?  The problem is that I do not have any gauge lights.  The High-beam indicator and turn signals work and the courtesy lights on the floor board work, but no tach, speedo, volt, or fuel light.  I want to make sure my circuit board is fine if I can.  Is there a way to test using the VOM? Thanks!

[jjr]

 Basically you're just looking for continuity...

 Do you have the Pontiac service manual?  it has everything
you'd need to verify each and every circuit.

 Joe

[ta78w72]

Did you check the bulbs?

Check pin number 1 on the white cluster connector for voltage.  You might also run a jumper from the canister to ground just to make sure you've got ground.  But ground wouldn't be my first thought.

If you have an automatic, does your shifter plate illuminate?  All those gauge lights as well as the radio illumination and the shifter plate come from the same circuit.   

You should also check the fuse.  One fuse controls all that.

Use the volt meter to check for current at the fuse.  Then check for current at pin number one.  Then check the splice where the gray wires spread out from one.

[HotBird]

Thanks a lot of your help!  First off, I don't have the Pontiac service manual.  Also, the car is a manual.  The stereo is also an aftermarket cassette deck.  I just got the TA in June and i'm the third owner.  The original owner put this stereo in and attempted to put in an old Audiovox equalizer, but there is a lot of "white noise" coming from the speakers when you give the car some gas.  I'm no electrician and definetly not a pro, but anyone can see that the wiring job under the dash is horrible.  Wires are twist-tied, split to other wires, and then split again.  This past weekend I only had time to take the dash off...I really haven't looked at all the wiring.  I plan on doing that this weekend.  But since I have this all apart, and in case everything else is okay, I wanted to know how to test the printed circuit.  I'll try to do what you guys suggested.

I wanted to add that there are other problems the car has...but I don't know if they would relate to each other.

The right turn signal remains lit if the heater is turned on for longer than 3 or 4 minutes.  I beleive there is a hot wire that is not connected/protected.  Also, once the parking lights remained on after I shut the light switch off.  Needless to say, I have a lot to check and correct.

I'd post some pics, but I'm not sure how.  I try hitting the "insert image" tab, but just get (img) text in the post.

Anyway, I'll try to check the fuse and pin #1 this weekend.  The fuse is okay, but I will check current.  I don't know if the courtesy lights are on the same fuse, but the floor courtesy lights work.  The dome light doesn't, but I haven't checked the bulb on that yet.

Thanks for your input guys!  i really appreciatte it!

[ta78w72]

Check how he wired the radio.  The original radio connector is black and had three wires in it.  One was yellow and was switched power.  A gray wire for illumination, and a black ground wire.  Make sure he didn't do something stupid with those wires.  The speaker wires would be green for the front....and blue for the rear.  The connector for the front speakers is white and the rear is blue.  Those speaker connector colors are for a stock radio.  They may still be hanging under the dash.  The black connector was part of your main dash wiring harness.

[dblhh]

I'd post some pics, but I'm not sure how.  I try hitting the "insert image" tab, but just get (img) text in the post.

Did you see this info about posting photos?

http://www.78ta.com/smf/index.php?topic=5167.0

[Rick]

I'll concur with Joe's advice on the service manual.  It's a bargain for the price, and Hitman sells them here on the site in CDROM form.  The manual is on the CD in PDF format, which is opened with the Adobe Acrobat reader.  It makes find things dog-dirt simple.  Frankly, I wouldn't own one of these cars without it -- there's no other way to know how it's supposed to be put together.

[ta78w72]

The courtesy lights (kick panel lights) and the dome lights are on the same circuit.  Different fuse from the dash lights.

Also, how do you know the fuse is good for the dash lights?  It may look good, but you've got to check it with a volt meter to find out for sure.

In addition the the CD, you might also try to find a hard copy of the service manual on ebay.  There are double page circuit schematics in color that the CD doesn't do justice to.  In addition, the pictures in the CD are dark and hard to see.  The hard copy service manual is much better in that respect.  The cd is invaluable because you can print out pages and refer to them as your working.  Then when the project is done you can toss the pages.  You don't have to worry about getting your hard copy service manual dirty.

[HotBird]

That service manual on CD sounds great!  I hate going back and using a dirty book. 

I'm set now on posting photos. It looks like the same Gallery I use on my website.  So I should be good now. I'll post some pics later on.

Thanks for all your guys help.  You've given me a lot of stuff to look for so I'll check on everything this weekend. 

ta78w72.......you mentioned about wire coloring for front and rear speakers.  Did the 78's have front speakers and if so where were they supposed to be mounted?  I'd like to bring this car back to stock.  The original owner put speakers on the door panels, but if they're not supposed to be there, I want them gone.

Again....you guys are great!  Thanks to all for your input!

[ta78w72]

The front speaker was in the center of the dash.  The rear speaker was on the drivers side of the package tray.

[HotBird]

Was that speaker set up strictly for '77, or was it for '77 and '78?

[ta78w72]

Both 77 and 78, however the electronics changed from 77 to 78 and you can't interchange radio's and speakers.

[HotBird]

Okay.  Here are a few pictures.  I found out that the stereo is not hooked up to any harness.  All wires from the stereo head straight to the fuse box.  Are the yellow, black, and grey wires in the photo below from the original stereo harness?  These wires were being used as twist ties holding up other wires!!! 

I'm not very educated on testing for continuity. 

ta78w72..... you said..."Use the volt meter to check for current at the fuse.  Then check for current at pin number one.  Then check the splice where the gray wires spread out from one.".  i don't know how to check at pin #1.  I see pin #1, but how do I check it? 

I tried to take the fuse out and oops...it broke.  So I've got to get another one. 

The last photo has two plugs that I don't know if they go together or not, or even were they go to for that matter.   They come out of the harness above the pedals.

[Eagle 1]

Here is an excellent link that may help.
http://www.firebirdtransamparts.com/techinfo/harness/harness.htm

[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?