Freaking dash... okay here's what i've done: took apart the cluster, cleaned all the contacts, resoldered the pins between the boards, cleaned the contacts on the side where it plugs into the wire harness. check the ground inthe engine, the ground in the cabin on the drivers side under the dash, and the big wiring harness in the engine compartment. I dunno what else to do. The thing is, one time, it turned on and was working perfectly until i turned the car off, and hasnt worked since.All the LCD's are black, the blinker and high beam indicators work normally. any ideas? or is it time to send it to get fixed? This thing is driving me crazy, the worst part is I cant drive anywhere... legally. I guess its time to call the one place... 'United Radio' was it?

 

Check for ground on pins D1, D2 and D23 of the 32-pin connector and on pin B1 of the 24-pin connector.

Also check for power at pin D18 of the 32-pin connector.

The cluster illumination control comes in on pin C9 and lamp supply on pin C-16 of the 24-pin connector.

Good luck with it.

 

You listed 4 grounds, I only knew of two. Could you give a location of these other two? I think im gonna pick up one of those Killebrew manuals also.

 

65Z01, I have Gordon's Digital Cluster Manual and my book does not show the pin numbers you mention for the 32 pin connector. Neither does my 88 Factory Manual Electrical Suppliment, 32-pin Instrument connector Page 8a-202-8. The Instrument cluster 32 pin connector I have shows 2 banks of 16 pins (C & D).

32-Pin connector: Pins C1- C16 and D1 - D14, D16 used.
Power ground is at D1 and D2. Signal ground is at D3. Cluster Illumination is C9.
24-Pin connector: Pins A1-A12, B1 - B2 used.
Switch panel ground is B1.

Sounds to me like you aren't getting power to the Cluster for LCD illumination or there is a problem with the power going to ground. The factory manual diagnosis section suggests that when the entire digital display does not light that you check pins D1, D5, D16, C16. The manual says D2 ground is not used in my 88.

Factory test A: Note: ignition switch to run EXCEPT resistance tests. ALL resistance tests to ground with negative battery cable removed. DO NOT use a test light to check resistance or grounds. That can cause damage to the cluster. Use a volt/ohm meter.

D1 ground to G201. (ground)
D5 battery power from LCD fuse, hot at all times. (battery voltage)
D16 ignition power from cluster fuse. (battery voltage)
C16 ignition power from cluster fuse. (battery voltage)

Gordon's book says the same thing.
Check D1 for ground.
Check D5 (orange wire) for constant 12 volts. (powers cluster microprocessor memory)
D16 & C16 are 12 volts ignition-on power, (pink-black wire from cluster fuse).

If all of the above test correctly and the fuse is good, the cluster needs professional servicing.

Let us know how it checks out.

 

My vette is an 1985, but the pinouts should be the same. Anyway, how would i test then? just put the pin from the voltmeter into that connection on the harness? Does anyone know the location of the 3rd (or 4th) ground wire on the car? I got my warning lights working when i cleaned the one ground. I think cleaning the ground would help.

 

Sorry, the above data was from Gordon't book, but I overlooked the fact that the connector pinouts were for an '84 cluster.

This data is from my '85 Vette GM Shop Manual:
D5=power from LCD Fuse, hot all the time
C16, D16 = power from CLUSTER Fuse, on in RUN
C6=power from TELTAIL Fuse, through headlight switch
D1=ground
D3=sensor ground

The only trouble shooting hint for a blank cluster is:
If nothing on the cluster lights check the LCD & CLUSTER fuses and the ground (from D1 with a Blk wire) behind the I/P near the LH side of the steering column.

The sensor ground (from D3 with a Blk/Wht wire) goes into a 46-pin connector at front of dash left of the brake master cylinder; from that connector it goes with a Blk wire to the LH reaar of the engine.

 

Thanks for the info. I guess the next ground to check is the one on the steering column that you mentioned. i'll just go through em one at a time. My cluster is good i think... after all why would it work occasionally? and when it powers up everything works fine while the car is running. Maybe a problem with the D16/C16 grounds?

 

I feel your pain Mikey, been there. What I can't understand is it worked fine until you turned off the engine? I'm thinking fuse-BUT if I were you I'd call Gordon at 1-800 398-3883, His fee is $10. per call, plus $3. per minute. I have his book and it's a must for all of us 84-89 owners. But he is the GURU, so it might be worth the call.