1996 Deville Dash lights go blank for no reason

Nightman · #1 (**permalink**) 02-05-07, 09:39 PM

For some reason my dash lights will go blank. It is a totally random thing, and if i shut the car off and re-start it they come back on. The headlights stay on, and the radio still works, but my gauges are gone as well as all of the backlighting on the dash and steering wheel controls.

My dealer said to try a new key, as the sensor in the key could be bad. I didn't really believe him, but it was a free try so I tried it out. It still does it.

When the lights come back on I get 7 codes. Here they are:

PC1602
PC1604
PC1626

AC2096

TC0072

PZ2096
PZ2255

Once I clear all codes they do not come back until the lights/gauges go out. Then those same 7 codes come back.

Does anyone have any suggestions or ideas?

Nightman · #2 (**permalink**) 02-06-07, 08:27 PM

nobody has any ideas or suggestions?

akimball442 · #3 (**permalink**) 02-07-07, 05:11 PM

does this car have a digital dash? i'm assuming? I'll look into the codes for you.

Nightman · #4 (**permalink**) 02-07-07, 08:57 PM

yep, digital dash with the fuel computer and the headlights that turn themselves on

akimball442 · #5 (**permalink**) 02-07-07, 09:00 PM

Those codes are oddballs. I found by a random google search that one of them involves a lack of communication with the IPC (instrument cluster). I think that could be caused by the general power loss you have. If I'm not mistaking, that vehicle has an IPM (instrument panel module) which is temporarily losing power from time to time. I'd get an FSM for that car if I were you. Cadillacs like to break, that's for sure. And they like to have dumb electrical problems.

At my job every day, I get to work on School busses. I work for a dealer. Even school busses have gone to full multiplex wiring (computer commands and serial data) to control all of the chassis and body functions. We had a problem with dashes for a long time that was caused by a breif loss of battery voltage. It's not going to be fun, but I'd suggest getting in the dash and checking connections, as well as looking for loose fuses. It may be a long shot, but it may also fix your problem.

I think that you may also have a failing IPM.. but I would be more inclined to blame a bad connection for this.

As for having it reappear when you restart the car, just like restarting the computer you're reading this on, everything reboots in cars controlled by a zillion microprocessors.

Good luck..

Hopefully somebody here has a list of error codes for that year car, I thought I had an FSM for it, but I dont

Nightman · #6 (**permalink**) 02-08-07, 02:52 PM

That is kind of what I was thinking also. Those codes really dont seem to have anything to do with the blank gauges/lights. I asked at the stealership, and they looked up a few of them.

They thought possibly a bad ground somewhere. I am trying the process of elimination right now. I have turned off the automatic lights and it hasn't done it in a couple of days. This doesn't mean that I found the culprit because as I said it seems to be a totally random thing.

Nightman · #7 (**permalink**) 02-10-07, 11:34 AM

Nope, turning off the auto lights was not the answer. It did it last night.

Tonkin · #8 (**permalink**) 02-10-07, 12:30 PM

PC1602 Electronic Brake and Traction Control Module (EBTCM) serial data to the PCM.

PC1604 loss of or invalid Instrument Panel Cluster (IPC) serial data to the PCM

PC1624 No password message is received by the PCM from the IPC prior to the VTD Fuel Decision Point or while running.

DTC 72 will set and the "TRACTION CONTROL" indicator will illuminate if communication between the EBTCM and the IPC is lost.

PZ2096 While the Ignition switch is in "RUN" modules communicating on the Class 2 Data Bus send a "State of Health" (SOH) message every 5 seconds to ensure that the system is operating properly. The PZM does not receive a SOH message after three consecutive monitoring cycles from the Instrument Panel Cluster (IPC).

PZ 2255 Generic Loss of Serial Data (Source ID Unknown)

All your symtoms point to the serial bus either opening up (connector) or grounding out.(connectors getting wet or cable shorting out somewhere.) The FSM shows all the connectors and a wiring diag so you will have to first start checking them out. I would check the connectors at the PCM and IPC first. Good hunting.

Nightman · #9 (**permalink**) 02-10-07, 11:32 PM

my car goes into the dealer on Monday morning. I have printed out all pertinant info in this thread and will pass it on to them. Thanks guys for all the tips and codes!!

Nightman · #10 (**permalink**) 02-22-07, 07:30 PM

Well, its been a long week and a half. Chevrolet dealer charged me $50 and didnt fix a dang thing. They told me to take it to a town 30 miles away to the Caddy dealer. Took it there. THey had the car for 7 days before they could replicate the problem. They found the culprit.

It was a bad ignition relay behind the back seat in the trunk. Cost $112 for them to find and replace it.

Finally, the nightmare is over!

tk1780 · #11 (**permalink**) 01-03-09, 09:11 PM

Is there another name for it? Or a fuller name or part number?

beldingsfinest · #12 (**permalink**) 09-18-09, 01:15 AM

Wow. This sounds like an issue I have been having as of late with my '96 DeVille. Same codes were set. I just had it towed to the shop and I had tried and tried to start it once after the dash went black. I had a bad starter they said. This may be true. I've been cranking it pretty hard with the bad fuel pump that I am replacing this weekend. However, that doesn't explain it losing power to the dash while driving. I'll definitely be looking for this part now. Anyone have any knowledge on where exactly it is and the part no? I will probably get it from RockAuto, but if Murray's or something local would have it I can try there. Any further info on the part would be most appreciated.

Thanks,
Zack

human · #13 (**permalink**) 09-28-09, 01:45 PM

I'm having a similar problem with my '97 Deville Concours, except mine has analog gauges. I don't get any active codes for it, though, just a couple of suspicious history codes, chief among them is B1971 which refers to a fault in the Inadvertent Power circuit, which sends power to some accessory systems for a few minutes after the engine is shut off.

beemer2k · #14 (**permalink**) 10-13-09, 09:22 AM

NHTSA campaign number 95V224000. Recall for instument panel cluster for vehicles only manufactured between 10/1/95 and 11/1/95. Only (1408) vehicles, despite the fact that there seem to be complaints about this problem throughout the entire model year. GM will do nothing for you if your vin falls outside the recall dates. Sucks for me and many others.

bigblockpaulie · #15 (**permalink**) 10-23-09, 06:31 PM

Hi, I have the same black dash now on my 96; so I need an igniton relay? Anybody know where it is back there? and if somebody has a part number it would help. Stealership is right; If it's something I can do myself I'm good. My dealer burnt me for the last time on a MAF harness for 440. Unbelieveable. Anyways I can't tell if I have codes...

Paul