Dana'86_305

Ok I made a search and couldn't find anything relating to this. I hope you guys can help out.

The car in question is the '86 camaro SC in the sig. When I turn my headlights or parking lights on, my tach, oil pressure and voltmeter go out and the right hand turn signal light stays on. This happened intermittantly before but now happens constantly whenever I put my lights on. Gauges work fine with the lights on. Another thing, those gauges bounce up and down when I have my right turn signal on. I figure it must be a short somewhere, but I can't seem to find it. Any clues? TIA

Dana'86_305

TTT

Anyone had this problem at ALL?

IROCmonkey

possibly in the headlight switch itself? are your exterior lights working normally? Could be a bad ground in the lights or burnt bulb, making a high resistance in the circuit.

Plus its common for your guages to bounce a little when your turn signals are on, from the slight voltage drops as the blinker works.

Dana'86_305

Hmm hadn't thought of the headlight switch..how would I go about checking that? Hook it up to a voltmeter? As for my exterior lights, I do have one out but the bulb is jammed in the socket and I am afraid to break it. As for my guages jumping, it is quite noticable quite a bit more than it should be normally. What am I going to do? It really sucks to not have my tach at night...

IROCmonkey

well I would definately replace that bulb, the lighting system does wierd things when a bulb is out, what kind is it? an 1156/57 bulb or one of the little 198's?

I am not sure exactly how you would go about testing the headlight switch, aside from just throwing a new one in...which can be a pain, because of the dash design.

Dana'86_305

well Monkey you have me at a loss..

I think it is the 1156 bulb but I'm not sure. Its so covered in dielectric grease that its hard to tell. Its the same size at the rest of the tail-light bulbs so whatever size that is. Have any tips on getting it out of the socket without breaking it? It's jammed in there pretty well. Are there any other ideas on if it's a ground issue or something else?

IROCmonkey

hmmm try pushing it in and wiggling it a little, see if it will move, you could try a penetrating lubricant such as WD40 or Liquid Wrench, Brakleen might work but it might eat the plastic. If you do break the bulb, just grab hold of the brass socket with a pair of needle nose (disconnecting the battery wouldnt be a bad idea)and twist that sucker out, only has to turn a half turn..I've never had one so stuck it broke on me, could be the socket is damaged. As far as grounds, examine the ground under the drivers side taillight cluster, its screwed to the body and is exposed to water, make sure it isn't rusty. Also has anyone spliced wires into the taillights? like replaced a housing or added a trailer light hookup? if so make sure those spliced connections are solid and clean.

If you are getting much worse voltage drop than usual it wouldnt be a bad idea to check and be sure your alternator is putting out enough voltage *and* amperage, an alt with a blown diode can be putting out 14+ volts but without much amperage behind it and cause wierd electrical issues. YOu might want to PM Deadbird or Vader and see if they have a wiring diagram of the headlight switch circuits.

racerx004

The problem is not in the headlight switch but in the printed circuit board behind the dash cluster.
What happens is not only are you turning on the headlights, but you are also turning on the lights that light up the gauge cluster.
There is probably a broken wire somewhere on the printed circuit.
Do a seach for
tach jumps with turn signal
by canadian beast.
This was a lingering problem for me. I ended up getting a gauge cluster out of a junk yard that was still in good shape.

One more thing to test, try turning on your head lights and turning the dimmer switch all the way down untill the lights on the gauge cluster go, the gauges should go back to normal.

Dana'86_305

thanks man, I think you nailed it! My mechanic told me it was a problem with the board, but I didn't beleive him...Guess I need to go find a 145 cluster now. White face guages here I come!! Thanks for the replies guys.

IROCmonkey

well learn something new everyday, good goin racer

hmm you'll still want to fix that burnt out bulb tho

Tafsky86

Hey guys!

This is the first thread that describes EXACTLY what I have been dealing with for almost two years and no one has been able to help me. I replaced all bulbs and the headlight switch, no change.

This may be a stupid question... what do you mean by printed circuit board behind the cluster? I also have an '86 Camaro (IROC 305 V8). All the guages are individual... so there is still a printed circuit board? Please understand I'm not asking in a condescending tone. PLEASE help? One of you mentioned a 145 cluster... does that mean the tach? Please help me...

Is the printed sicuit board on the back of the white colored unit that all the guages plug into? I am and will be grateful for any help you can offer!

Matt

IROCmonkey

LOL after all these years I may be the only one still subscribed to this thread. Back from the dead.

Anyway, yes there is a circuit board on the back of the cluster, the white housing. Usually the housing is held in by 2 small nuts in the sockets at the bottom where the idiot lights are. That board feeds the guages, and all the instrument cluster lamps. To remove the cluster, take the nuts off, and hope you have enough play to get your fingers behind it and pop the speedo cable, there is a retaining tab to push down and then it should pull out. The wiring harness should unplug on its own.

When we mention a 145 cluster, it means one of the rare(r) cluster from 87-89 cars that have a 145mph speedo. All cars pre 86 have 85mph, and after most cars have 115mph.

Usually this type of lighting issue is a bad ground somewhere.

GeorgiaSS

Hey Monkey. I just got a 86 iroc from a guy that did a engine swap. It was TPI but he went to a older motor and carb. 350 from a 74 Z/28. anyhow none of the gauges work. fuel gauge max's out when I turn on the key,Tac or anything. Pulled the front off the cluster and checked for power going to the fuel gauge, it has power going to the top right prong. You think its a ground problem? I dont know what all this guy cut or took out of this car.

IROCmonkey

Do the instrument lights work? turn signals? if they do then you have power to the cluster and I would isolate the gauges.

Speedo - this is purely mechanical, cable runs from back of gauge to the transmission tailshaft. If speedo is not working then it is most likely a disconnected or broken cable or a broken input gear.

Tach - this is electronic and picks up from the distributor, I cannot remember if it routes through the ECM or separately. If the guy who did the swap replaced the stock HEI distributor and electronic ignition, then the tach will not work.

Oil Pressure - this is fed from a sender that attaches near the back of the engine by the distributor. If this sender is no longer there or disconnected this will not work.

Water Temp - this is fed from a sensor in the drivers side cylinder head, if the sensor isn't there or disconnected this will not work. Sender is brass, with 1 wire (usually green or brown) on the front half of the head. It is also not uncommon for this particular guage to fail in itself.

Fuel - this is a standard resistance type float in the gas tank. The sender is attached to the pump assembly IIRC. If the swap replaced the electric pump w/ a manual this may be the problem. You can check the connector at the top of the tank, there is a 3 (i think) wire weatherpak that connects to the top of the tank, you can usually find it by following the fuel lines. You need to be flexible and have smallish hands to get in there without taking anything apart.

Volts - I honestly am not sure where the gauge picks up its reading, but if any major hacks of the wiring harness were done during the swap (likely) it is possible this has been compromised.

Depending on what your goal is with the car it may be just easier at this point to buy an aftermarket setup and start from scratch. Depending on the modifications (damage?) made before you bought it, it may be anywhere from difficult to impossible to get all the stock gauges working properly.

GeorgiaSS

Lights in the dash are working, half of them anyway. Turn signals work. The guy put some after market gauges under the dash for oil and temp. oil has the plastic tubing and the temp is the manual kind. I thought the circuit board might of been bad but since you said if I had dash lights it had power. I already took the that pain in the *** instrument cluster out. I guess the speedo cables needs replaced and some of the bulbs in the cluster too. Thanks for your help. Haven't bought a car in this bad of shape since high school.

GeorgiaSS

You think it would be a good idea to replace the circuit board since I have it out? Who carries those too?

IROCmonkey

Without having looked at it or done any troubleshooting myself, I would say replacing the circuit won't help. From what you are telling me it sounds like the engine swap was done without any attempt to preserve the original connections. Basically all the stuff that feeds the gauges is probably gone.

I am guessing that the current engine setup is a carb with manual and vacuum setup, not computer controlled. Most likely the distributor is now a vacuum advance type, might still be an HEI but probably not.

Before getting too far into the instruments, I would check the extent of the damage (at this point damage seems to be the right word). Tak the kick panel down from under the passenger side dash. There should be a silver box (about 8 x 6 inches) and a crap load of wires just above the panel. The silver box is the ECM. And the wires are the primary engine harness. If that stuff isn't there, I don't know if any of the original instruments besides the speedo will work.

Speedo is pure mechanical, you have basically 4 parts: gauge, cable, driven gear, and drive gear. Check the cable first, if you have the cluster all the way out you should see a thick black cable with a metal end there is a kind of clip on the end. Sticking out of the end should be a steel cable, the end is formed into a square. JUst grab it with a pair of pliers and pull it out, it may require some force. you should get about 6 feet of cable (I think, been a long time since I've pulled one). If the cable is ok with no bends, kinks, fraying, or other crapiness. Get some synthetic grease and coat it with grease as you feed it back into the housing until just the tip is sticking out like before. Stick the cable into the spot for it on the back of the speedo and push it until the clip locks into place. Drive it and see if the speedo works.

GeorgiaSS

The guy that owned the car had it for about 8 years, he finally got around to putting a motor in it 3 years ago, he died 6 months later. His grandson drove it 1 1/2 ago and the trans went out. Its been sitting in a yard behind my mothers all this time. I went and asked about and got the casting numbers off the back and front of the block. Its an early 70's 350. Numbers end in 10, so I got it for $400, motor ran after pouring gas in the carb. Doesn't have a dent and just a little rust on the hood. I'll replace the burned out bulbs in the cluster and stick it back in and check the speedo cable..

Thanks for your info.

IROCmonkey

OK, shame the guy didn't get to finish the car, sounds like it is worth fixing up.

Anyway, if the cable is ok and speedo still doesnt work. Next thing to check is the driven gear at the other end of the cable.

You said tranny went out? Did you get that fixed already?

GeorgiaSS

Trans has been rebuilt with a shift kit and vette servo's. I pulled on the end of the cable to the speedo and it came out, only had about 2 ft worth. I've got one ordered. As soon as i get it back together I'm going to replace the temp sensor to see if the gauge works. Can't drive the car yet, no title to get a tag and open headers would show get my butt in trouble. I'm getting it ready to paint. Just trying to get some things fixed before I paint it.

Thanks for your help.

IROCmonkey

You'll probably have to take the cable housing loose at the other end to get the rest out. Might even have to feed the new cable to push the old through. If you haven't done it before, the cable attaches to the transmission on the right side of the tailshaft housing, it has 1 bolt with a retaining clamp that holds it in. Be careful when you pull it, cause it will puke trans fluid out.

Is there a sensor plugged into the head already? is there a wire attached? The sensor plugs into the water jacket, so it will leak coolant when removed. Where did they plug in the aftermarket gauge sender?

GeorgiaSS

They have the after market temp gauge plugged in to the head. I started to pull the trans myself but I had shoulder sugery 4 months ago and I don't have full range in my shoulder yet so I had it towed to a friends shop. About the only thing I did was undue the speedo cable and linkage to the shifter. I saw the wire to the temp sensor laying or tied around a brake line .I'll go get one today and see if it works.

Thanks

GaryM

once again ThirdGen.Org saves the day.... had exact same symptoms, but found a different root cause on the instrument cluster printed circuit board. Two of the copper trace tabs on the right side connector interface were twisted way out of position. Probably from the R&R when I cleaned gage faces 2 years ago. Several other tabs coming loose from the plastic backing, so gently checked to find the loose ones and super-glued them back to the plastic backing.

A friend gave me a frustration saving tip to remove cluster; if you have cruise control, break speedo cable loose at CC module in engine bay and pull cluster out to where you can actually get hands around the cable release at the gage.

red rock

iTrader: (2)

Just for the sake of this old thread, if you have a break in the printed circuit copper, you can shine up the break and put a drop of solder on it. Also check all grounds for a good connection.