PaceCarChris

Here is one for ya, whenever I light up the gauges the tach and oil pressure needles take a nose dive. I have replaced the headlight switch (that was a pain) but that was not it. During the day both gauges work fine. On top of that the cig lighter is non-functional also = no radar detector. Could these be related? Anything simple I am overlooking here? Thanks.

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1982 Z28 Indy Pace Car
Stock Fiberglass hood
Balanced and Blueprinted 350
Holley Dominator Manifold
850 cfm Edelbrock Q-Jet
Accel Supercoil/Extreme 9000 wires
TH350/Transgo Shift Kit
Hedman Headers, no cat

RSpeed

Good one.Only thing I can think of is a short somewhere between one of your instrument cluster bulbs and ground wire for your gauges.Pull your cluster out and and check out everything back there.Also check to see if a bare strand or anything conductive somehow managed to find its way back there to touch across some of the traces on the cluster's circuit board.If I'm not mistaken,those two gauges use a ground signal to operate and may be shorting across the positive terminal of your lights when you turn them on. Only thing I can think of at the moment.

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"So,tell me Mr. Stang. How's life like living in the exhaust of a Chevy V-8?"
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'91 RS 5.0 TBI
New paint-solid black
ROH Snyper wheels-17x9 wrapped in 275/40/17
Eibach sportline springs
Flowmaster cat-back
TBI mods
MANY more to come!!!!

kevinc

I troubleshot the same symptoms...dead/maxed gauges when the parking lights were on and whacko fluctuations when the right turn signal blinked.

Root cause was a break in the Mylar printed circuit board behind the instrument cluster. When I removed the cluster, the break in the copper circuit was easily visible.

Fix was to gently remove the plastic insulation using a razor blade about 5mm around the break, then use a Rear Window Defogger Repair Kit (PepBoys near the Rear View Mirror Adhesive) to bridge the break. Finished up with spray lacquer to keep moisture out, good as new for 1.5 years now.

-Kevin

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1982 Z-28

See http://www.mycar.net/mafb/registry/detail.cfm?id=276 for details

RednGold86Z

iTrader: (1)

I have the same problem. How do you get the cluster out far enough to get to the back? Is it easy?

Hank Brote

You have to remove the speedometer cable from the speedometer. There is a clip on the rear of the guage. Push the clip in and the cable will come off. I hope you have little hands, there isn't much room up in that there dash.

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Hank
87'IROC Z28
Hanks 87 IROC

PaceCarChris

Resurrecting a really old thread of mine- yes it's really taken me this long to get to it...

Pulled the cluster out and went over all of the PCB traces with a voltmeter- everything appears to be connected with a a minimum of resistance (I think max anywhere was 20 or so Ohms). As far as I can tell, no breaks in a 23 year old camaro PCB. Replaced all of the gauge lighting bulbs with the "xenons" from Macewen. Nice. Cleaned up all the connections on the bulb socket/housings and the tab connections to the dash with a little file. Installed the cluster and secured the two speed nuts. Fired the car up and everything worked- lights, dimmer, gauges, turn signals, and the tach and oil guage operated with the dash bulbs lit. Let the car sit and run: tach, oil gauge and the three bulbs around the tach gauge all die. Frustration. Give the cluster a little "push" to seat it. Everything comes back to life... then dies again a few minutes later. So close... Cannot repeat the "push" phenomenon. Kill the dash lights, gauges spring back to life.

I'm no expert on electronics, but seems to me I either have an intermittent/bad connection somewhere, a bad ground, and/or a short. What I don't get is why it will work for a little bit and then quit? Other gauges and lights share this ground too, so why would only the oil and tach die?

The handy shop manual shows the ground running through to all of the lights that die as well as the tach and oil gauges. But resistance even through the length of the circuit is minimal.

I'm going to try to "expand" the copper tabs on the male part of the wiring block that the gauge cluster seats into in hopes that I can get a cleaner/tighter connection for everything. Other than that, anyone have anything else to look into based on my symptoms? I can supply the wiring diagrams from the 82 shop manual if that helps, they're aren't a whole lot of use to me. Maybe someone who can read them could pinpoint a few places back there to check. The whole dash is torn apart and the car is not a daily driver anymore, so it's not going back together until it's fixed. I really hope it's something on the cluster, and not in that mess of wires buried back there...

PaceCarChris

Well it's not the connections into the dash. One more weird thing I forgot to mention- after the tach/oil pres guage die, sometimes I can operate the tach needle (move it back and forth) with the headlight dimmer ****...

MADMANAMI

I have an 83 Camaro with the same exact problem. I also just wasted $30 on a new headlight switch. The weird thing is if I turn the dash lights completely off with the headlights on the tach works normal again. About the only thing I've accomplished is the speed at which I can remove the dashpad. If you've figured out what is by now I beg you PLEASE to let me know, and if I figure it out I'll definitely let everyone else know cause it's drivin' me friggin' nuts.

PaceCarChris

Sorry, haven't gotten to it yet. Am 99% sure at this point it's something with the printed circuit board, but it's just not that obvious to me; I have no "easily visible" break. You'll have to pull your gauge cluster out and check out the flimsy green board on the back, no need to pull the dash pad off. Hopefully you'll have more time to get at it than I do at the moment.

MADMANAMI

Thanx for the reply, I'll try to get to it tomorrow. fingers crossed in Iowa

fastgascar

I am bringing this one back from the dead. Did we ever find the solution to why this was happening?

Guest

I just did an lt1 swap, prior to me pulling anything apart, my dash was working perfect. Now when I turn the key forward to power everything, a few lights are barely (i mean barely) on around the right side of the speedometer (security light barely illuminated), my fuel level gauge doesn't work, and my tach dies when i turn on the lights. When the lights come on the instrument panel, all lights look alright except those few that illuminate barely go dark...

Guest

Alright so I figured out my problem after some hardcore troubleshooting. Hopefully this will help someone else out in the long run.

Apparently in the bulkhead C100 connector there is a black/white wire in C7 which for some reason is labeled "Engine". Following a wire diagram, I found that C7 has nothing to do with the engine, it is in fact a ground wire.

Now here's the thing, there is also another black/white wire, that is for the SIR system, don't confuse the two. However, both need to be grounded. Find the C7 black/white wire and make sure it has a proper ground.

My guages/lights all work fine now =)

rough

Double Resurrection!
If you have fixed it reply back
Knees deep in days of wire tracking

8t2 z-chev

sounds like a weak ground-can't cope with the current
pulled by the bulbs and voltage rises on the cluster
ground circuit instead of staying at 0 volts like it should
with a good ground connection...

82_Camaro

my tach just isn't working i rebuilt the engine and dumped it back in and the tach just completely doesn't work at all. wondering if anyone has a clue on what it might be

Guest

Trace the wire labeled "engine", it's black, and located in the c100 connector. IT should be grounded. Without it being grounded, it will do all kinds of funky stuff. I had this problem with my lt1 swap.