Hey guys, my temperature gauge in my 86 camaro z28 305 carb 5spd is pinging out. I removed the cluster and installed a new gauge and at the same time went ahead and replaced all the bulbs since some where out and others where dim.

Well after installing the new gauge I of course tested it before putting all the trim and everything back on, and what happens is as soon as I crank the car the gauge pings out and stays there. If I tap the needle it will go back down (unsure atm if it reads the correct temp after that or not as I didn't let the car get to warm).

Also the same light bulbs that weren't working before are still not working with brand new bulbs.

So I was wondering if you guys think the circuit board on my cluster may be having issues, or is it more likely that the temperature sending unit (where ever that is) is the culprit? I'm not even sure if the light bulbs that are out are supposed to be on at all times ore if they only come on under certain situations.

Thanks!

 

The needle pegs when you hit the key because of the gauge/bulb test feature. To an extent, it's supposed to do that. If it sticks, it's probably because the gauge is faulty. Did you replace it with a known good gauge or NOS new, or just another potentially faulty gauge?

 

I got it from a local camaro / firebird specialty salvage yard. They pulled it out of a cluster that had supposedly been fully tested and was working.

I'm also concerned about the light bulbs that aren't coming on though, as I said they are brand new bulbs so I thought they would be on now unless they only come on under certain conditions. That is why I'm worried about possibly a bad circuit board on my cluster.

Another anomaly, if I move the dimmer switch at certain points the needles will jump, and the gas gauge in particular will drop a quarter of a tank in reading. And the lights will only come on in a very narrow range of the dimmer, max brightness, or about halfway to the lowest dimming and all of the lights are out.

 

Indicator lights or gauge illumination lights?

 

They are in the gauge area not the ones at the bottom that I know are for indicators. Like the one right above the speedometer. There are a couple others too.

Here this would be easier, I just went out and took a picture of the cluster you can see which lights aren't on =P



Notice I have circled the left turn signal, it does not blink when I turn it on, the right one does however.

 

Here's the thing... It's possible your problems are related, and it's possible they aren't. The plastic circuit board on the back of the cluster can be damaged, the traces can come off the plastic or make poor connections. A visual inspection is your best bet.

By design, the indicator lights and gauges will come on/max out when you turn the key to a position in between run and start. If the needle on the coolant temp gauge is physically swinging off the scale, it could be hanging up on the edge of the gauge face. During that bulb test, the gauge is working independently of the sending unit. If it doesn't pass the test, the gauge itself is probably bad. The sending unit itself is in the drivers side cylinder head, with a single green wire leading to it.

If the lights you're troubleshooting are indicators, the bulb test should light them. If they're illumination they only come on with the headlights. If some of the illumination lights come on, they all should, unless the circuit board, sockets, or bulbs themselves are bad.

Right off hand it sounds like maybe your headlight switch/dimmer is used up, but I'd troubleshoot it a bit before you throw new parts at the problem.

 

Thanks for the advice, unfortunately I don't know how to troubleshoot it further without throwing parts at it =/

My previous temperature gauge did the same thing, that is why I replaced it. I would think getting two temperature gauges that exhibit the exact same problem would be rare, but I suppose it is possible.

The headlight / dimmer switch probably does need to be replaced as it is pretty worn out I'm sure, almost everything on the car is the original stock except for the stuff I have replace so far and that isn't one of them. I'm not as worried about it I can set it in a position that works for now, I just need to get the cluster working properly. Especially the temperature gauge because I'm concerned with the motor over heating. The electric fan isn't coming on automatically like it's supposed to right now, I plan to try replacing the thermostat to try and fix that soon, but for now since my AC is not connected I"m just turning the AC on as a fan switch. But I need to see the temperature in case I turn it off and forget to turn it back on for some reason!

When I replaced the bulbs, the circuit board did not look damaged anywhere except a few small scratches on the bottom that I think I put there myself taking it out due to screws at from the bottom of the dash sticking up at the edge of the cluster area. But I traced them and neither went to any of the lights that have problems, one went to the gas gauge which is still working the same as before, and the other went to another light that is coming on.

I suppose the bulb holders themselves could be bad since these are the same lights that weren't working before. I guess I could try moving one of the working bulbs to a non working spot and see what happens. If it works then it must be the bulb holder and I can get some more of those, but that will still leave me with the problem of figuring out the temperature gauge.

 

that happend on my 86 iroc. it may not have been the "correct" fix, but i took off the dash bezel and took a tiny trim nail and cut it down to clear the clear plastic part of the bezel, and put a dab of 3m glue on the head of the nail and placed it at the top reading of the temp gauge.

it actually looked realy clean and factory looking. but it worked great. now it shoots up and stops on the peg (nail) and then back down after cranking. like a normal gauge lol

and i did it to my fuel gauge too, becase sometimes it would get stuck on "full" and not come down for weeks lol.

 

Actually you'd be shocked to see how many of these cars have the exact same issues as another. I wouldn't be at all surprised if the coolant temp gauges have a high failure rate. So far all three people posting in this thread have the same problem. I've already narrowed the issue to a faulty gauge in my Iroc, it's just not worth my trouble to fix it since I never drive the car. It's on my long term to-do list. Some day I'll get around to it.

The fan issue is another topic... There are a couple thousand threads on the topic, take a look on the cooling forum and you'll probably be overwhelmed. Grab a Snickers, and . If you really need an accurate temp gauge, you might want to consider an aftermarket gauge.

Do some diagnostics... Moving a couple good/bad sockets around will help you isolate the issue to the bulbs or sockets. Remove the bulb from the socket, and test the socket with a test light or DVOM to see if it's getting voltage. Obviously since some of the instrument illumination bulbs are coming on, they should all be getting power. However, there is a catch... The illumination bulbs aren't all driven off one wire. There are 3 power wires for the bulbs. They're all in the C2 connector behind the cluster, it's the one on the left side. The pins/wires on C2 are numbers 1-7 left to right across the bottom, and 8-14 right to left across the top. Pins 3, 11, and 12 should have voltage with the park/head lights on. If they don't, trace the gray wires back to the splice at the harness behind the dash, they all originate in the same place.

 

 

Ok, so I got my temperature gauge replaced again, and this gauge doesn't peg out. It shoots up when starting the cars like the others but it doesn't go up quite as fast and comes back down.

The problem is I still am not getting a temp reading on the gauge.

I replaced the temperature sending unit today, checked the wire and do not see it damaged / grounding out anywhere and it appears to be connected properly under the dash.

So I'm not sure what else could be the problem? I've triple checked my circuit board on the back of my cluster and everything appears good, no damage or broken paths that I can see.