dash light problem

[KWinBigE]

First, I just bought a 71 Custom 10 and I sure appreciate what a wealth of knowledge there is on this board. Already picked up a lot of good info.

But.....

Here's one I haven't seen before.
The dash lights on my '71 work but are real dim. I turn the knob all the way just short of the dome light coming on and they get a little brighter but still very dim. All external lights and signals work as advertised.

Here's some possible clues.
Both turn indicators come on (and stay on) when I turn on the lights, but the signals and flashers still work fine.
The dash lights are even dimmer when the high beams are on.
The dash was replaced with a tach dash (before I got the truck).

I'm thinking it might be a printed circuit board problem?

Any suggestions for troubleshooting further will be appreciated.


Thanks,

Kim

[PanelDeland]

With any electrical problem on these trucks the first thing the BB members are going to tell you is to "Check the Grounds" There seem to be a lot of these type problems with these trucks.I have put grounds from block to firewall,body to frame, and from the ground on the printed circuit board.This seems to have taken care of my electrical gremlins.Also, check to see that all of the bulb holders are turned the correct way.It sounds as if the dash is grounding thru another circuit rather than a ground.Happy hunting and good luck!!

[Piston]

I've seen the ground strap burn through the printed circuit board and cause that exact problem. When the oil line (factory copper) is connected, the gauge cluster will ground through that. But if you have somethign else hooked up or are using plastic line, your ground is now gone. Check the grounds..........

[68 Stepside]

that's exactly what happened with my truck...I had to ground the cluster...works fine now.

[Hutch]

Welcome to the board
You have come to the right place for all the answers to your Chevy Truck questions.

First let me give you a link to GMC Pauls great web-site.
The link will take you to the tech tips section where there is a diagram of the changes to the wiring that need to be made if you are switching from idiot light dash to the more common guage dash.
GMC Pauls Tips

I was not sure if your original dash was the idiot light style but thought that you may want to check the wiring to see if the previous owner did the job right.

Like the others said check your grounds.

My 71 has symptons just exactly as you described yours but mine is the idiot light version, I have had mine out and I can tell you that the printed circuit is a real mess.

Have Fun

[Blue Beard]

The ground problem would be the first to check.

Also check your positive battery cable.

I was having a very similar problem. Went through alot of areas looking for possible short.......finally found the postive cable shorting out behind the exhaust manifold.

As some other posts tell about removing the negative cable and placing a light in line between it and the neg post....will show a draw on the bat. Good indication of a short.

I ended up taking the under hood wiring loose at the firewall to the fusebox to isolate the short under the hood and went from there to find it.

Good Luck.....

[krazy_texan]

hey does your whole dash blink when you turn on your blinkers and does your highbeam indicator stay on until you turn on your highbeams, mine does and it has gotten a little better since i grounded it but it still does not work properly

[Lippyp]

I had similar problems, check the floor mounted dimmer switch. Mine was corroded to hell and all the problems dissappeared when it was replaced. I also added an extra ground wire from a bolt on the back of the dash cluster to the dash itself, but it was the switch that cured the problems.

[Longhorn Man]

krazy texan... does your fuel guage work? It sounds to me like someone installed a guage panel where a dummy light panel was.

[KWinBigE]

BlueBeard - Just put a new Positive cable.
Krazy Texan - The fuel gauge and everything else on the dash works right.
Thanks for all the replies, I'll post a fix when I find it. (Goin' after the ground as recommended.)
Kim

[Jwill41]

I have had to replace the dimmer switch and plug on both my trucks. I think it was caused by a bad ground somewhere though.

[GMC Jim]

and when you have solved your problem; I might suggest that the dash lamps ( #194; 2 C.P ) be replaced with #168; 3 C.P.....as they considerably brighter.....( you can control the brightness with the headlamp switch and the brightness is there if you need it /..... You might want to consider leaving the headlamp hi/lo indicator lamp with the original #194 lamp.......
Ialso rewired the lamp to the heater/air cong. control panel so that it is connected to the parking lamp circuit..... In other words; the heater/ air cond panel has a constant brightness.............