Alternator Light pRoblem

[84GNwith87eng]

I know that my alternator isn't charging because of a problem with the volt light. The light does not come on when car is on or when key is on and engine is off.

Where should I check to see if there is a break in the line? Or could it be the plastic on the back of the gauge panel? Maybe a break somewhere?

 

[blueta]

Is the bulb good? Did you verify that it wasn't charging with a volt gauge?

 

[olds443]

I just went through this same problem with mine after the dash harness change. Did a lot of searches and testing.
Here is part of a post I found that helped me figure out my problem. On mine it was a bad connection to the dash light not completing the circuit (light not coming on when key turned to on). From the searches I found it could be a bad connection or bad bulb.

Posted by; NJVetteGuy
I'd rather be racing...

Join Date: Mar 2004
Location: Union NJ
Posts: 184




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On the plug that goes into the alternator, check for voltage at the little brown wire(I'm pretty sure it's brown anyway). Should be around 2.5V with the key on, engine off. If there isn't voltage there, check to see if the bulb for the idiot light in the dash is blown. If it is, the alternator won't get trigger voltage and will not "turn on". The SM voltage reading will be off as it's reading the available voltage after everything else has consumed some of the power. With the alternator functioning properly you should read about 13.4V DC on the SM.

 

[blueta]

I know in my 69 when the bulb blew it didn't get a reference signal and wouldn't charge. It was a brown wire on that car too. I got tired of relying on bulbs so I took another 12 volt source and wired it to the signal wire on the alt. You will have to solder in a 470ohm resistor to make it work though

 

[84GNwith87eng]

Yes, I know the bulb is good, I'm just getting no power to the brown alternator wire and I can't find any breaks

could it be the plastic behind the gauges? Could THAT have a break in it?

 

[wagon]

I had the same problem recently with my 87. I swapped alternators twice and still nothing. Then I noticed the bulb wasn't working. I replaced that, still nothing. While checking the bulb to see if maybe I put in a dead one, the light flickered on. It turned out that it was a bad connection where the harness pllugs into the dash. Once I got that cleaned up, it was charging in the mid 13s. With these cars getting older, the connections can be a problem.

 

[87 Pete]

Yes, I know the bulb is good, I'm just getting no power to the brown alternator wire and I can't find any breaks

could it be the plastic behind the gauges? Could THAT have a break in it?

A couple years ago, after I got my t-type out of storage, I had the same problem, the bulb was good, but it would not light. I removed the cluster and careful cleaned the flexible contacts on the back of the cluster, as well as the copper contacts on the firewall. Try using a pencil eraser or some 1200 sandpaper. Mine has been fine ever since (3+ years).

Casper's also sells a plug-in fix, if you want to try that.

Pete

 

[tom t]

Casper's also sells a plug-in fix, if you want to try that.

One of the first mods I made to my 86 GN:

http://www.casperselectronics.com/M...creen=PROD&Product_Code=102032&Category_Code=

 

[Red Regal T]

Everytime I encountered this problem, it was a matter of unfastening the dash cluster and jiggle it around until I got a lite. Of course, clean the connection and when you find the "sweet spot", where the lite stays on, tighten the cluster back in place.

 

[84GNwith87eng]

I'll buy the casper's fix, I don't care about the bulb lol

 

[6=8]

Lots of chances with bad connections! The Flex circuit connector, the plastic bulb socket spring tension, the bulb socket copper contacts, the copper contacts on the flex. Any one of these points of contact can get weak and make even a good Alt. appear bad.

Here is what I did to fix it when mine started acting funny:

Removed the cluster, used some steel wool to brighten all contacts mentioned above, then coated everything with dielectric grease to prevent oxidation before putting it back together.

The bulb socket for the BATT light is special too, and has that 480 ohm resistor. Can't just throw any replacement in there!

Also, the contacts on the fuel gauge were given the cleanup treatment. That helped the consistency... It now reads FULL when I fill it up, not 3/4 of a tank!

I knew the Caspers fix existed, but having a more accurate fuel gauge and brighter instrument lights made the effort worth it.