Help! My gauges stopped working, what did I do?

[JoshT]

My truck is a 68 model, but the body, instrent cluster and wiring are all from a 70 model. Pulled the gauge cluster last week to clean it up. Found that the flex circuit was in bad shape, at least one broken terrace and starting to fall apart. Ordered a new replacement from Dennis Carpenter and got it installed this weekend. Now none of my guages work, well obviously the speedometer world, but the other 4 aren't.

What works:
Backlights
Left turn signal indicator

What doesn't work:
Temp gauge
Oil gauge
Fuel gauge
Ammeter (I assume, it doesn't move)
High beam indicator
Right turn signal indicator

What I did:
New flexible circuit
New bulbs (HiPo parts LEDs)
New lens
Disassemble
Clean
Paint needles
Reassemble

Ammeter may or may not be a separate issue, did 3G alternator upgrade but used PA-performance kit to retain ammeter.

Didnt know where the high beam indicator was at before starting, so don't know if it was working before. Turn signals we're spotty anyway, so can't really say that's new either.

The guages did work before. When I pulled the cluster I noticed someone bypassed a broken terrace in the flex circuit by jumping a wire from the connector over to the ICVR. That was primary reason for replacing the flex circuit. I reinstalled everything the same way it came out minus the added jumper wire, but now the gauges aren't responding.

Not sure what I could have done wrong. Help please!

[JoshT]

Well after getting the cluster back home I found one thing that was wrong. Apparently I my tiredness and haste I managed to destroy a couple of the gauges by over tightening the screws. Seems like the "thread cutting" nuts used to hold these gauges in decided to make new threads when I over tightened, then cross threaded when I tried to remove them. Broke mount bolt "cardboard" on temp and oil pressure gauges. Didn't break it, but can see sign of over tightening on fuel level gauge.

Guess I'm off to eEay to hunt for used replacements, or else I'm stuck getting new. Really don't want to be buying new.

Still doesn't explain why they weren't working though. Everything was still connected electrically until I broke the leads attached to the mounting screws while getting the oil pressure gauge loose. Electrically the temp gauge is still intact, but it wasn't working.

[BayStYAt]

Did you get it straitened out? I had issues myself. I decided to leave my original cluster in and put all mechanical gauges in.

[Thipdar]

Well after getting the cluster back home I found one thing that was wrong. Apparently I my tiredness and haste I managed to destroy a couple of the gauges by over tightening the screws. Seems like the "thread cutting" nuts used to hold these gauges in decided to make new threads when I over tightened, then cross threaded when I tried to remove them. Broke mount bolt "cardboard" on temp and oil pressure gauges. Didn't break it, but can see sign of over tightening on fuel level gauge.

Guess I'm off to eEay to hunt for used replacements, or else I'm stuck getting new. Really don't want to be buying new.

Still doesn't explain why they weren't working though. Everything was still connected electrically until I broke the leads attached to the mounting screws while getting the oil pressure gauge loose. Electrically the temp gauge is still intact, but it wasn't working.

Gotta ask... did you get the flexible circuit for a cluster with gauges, or the one for idiot lights?

[JoshT]

Sorry, forgot about this. Got it mostly working again. Had to replace oil pressure gauge because I broke the circuit. Was able to glue the mounting bolt on the coolant temp gauge back in place. Problem with stuff not working was a bad Instrument voltage regulator, new one of those and it started back working.

Fuel gauge is not right, when full it reads 3/4 tank and occasionally will stop working when hit a good bump. Most likely due to the new sending unit and/or bad connection, but not too worried about it at this point. Hoping to replace the new in-cab tank and sending unit with a new under-bed tank in the not too distant future.

Coolant temp isn't right either, but that's because its no longer in the intake. Needed to put the temp gauge for the Sniper EFI in the original location, so moved original sensor to the t-stat housing. Sniper handheld also has a temp gauge (among others) and I've got it mounted to dash.

Only thing not working at this point is the high beam indicator. Probably a wiring issue between the indicator and switch.


Got gauges, so got the circuit for gauges. Yes, I verified that I received the correct circuit. Not only did part numbers match, but a visual check of the traces confirmed that they match as well.