Cadillac Owners Forum banner
102K views 34 replies 25 participants last post by  96fltwdrwd 
#1 ·
Digital Dash Repair Tips:

Digital clusters can be problematic in Cadillacs ...and other cars. It seems there is a deficiency of good troubleshooting info, or it is scattered in several posts. Hopefully we can get a thread going that will be useful for those who want to "hunt" down and resolve problems w/o paying a king's ransom. I invite others that have resolved dash problems to share their troubleshooting methods. If enough information is added, perhaps this can be a "sticky" thread to help others.

Problem: For me, it all started with an annoying intermittent cluster problem in my 92 Seville that became more and more pervasive. Here were the symptoms: After about a 1/2 hour or so of operation, the cluster would go completely dead, all needles flatline and radio light blank. The fuel data and HVAC lights would flicker and finally go blank. As a result, the HVAC system would go into a default defrost mode and 75 degrees heat (annoying in the summer and winter).

Finally, I got serious about fixing the problem. Since it was an intermittant problem I figured it would be relatively easy to spot and resolve. The following article is the steps I took to do that. I have some very basic electronics repair experience which helped, but anybody with decent mechanical skills should be able to apply the same strategy. I may might do a more detailed write-up on on my website (www.RepairNation.com) in the future with some pictures.

There a number of things that can cause intermittent problems like this: The VERY first thing to check is the ground on the starter and body. This was such a problem in the early 90's that Cadillac came out with a special ground bracket to retrofit cars with. My neighbor works at a Cadillac dealer and he says that a bad ground was the number one problem that caused digital cluster to flicker. Don't do any repairs w/o ensuring you have proper grounding.

It's important to know that the following modules all communicate on a Serial Data Line:
PCM - Powertrain Control Module (the ECM)
ACP - Air Conditioning Programmer (for the HVAC))
DERM - Diagnostic Energy Reserve Module (GMs fancy term for the Air Bag system)
EBCM - Electronic Brake Control Module
IPC - Instrument Panel Cluster

Information from these separate computers share information on a **serial** data link to the cluster. It's a loop so if only one break in the circuit occurs, it will not necessarily cause a loss of communication (com can go the other direction in the loop). But issues with one module can have rammafications with the performance of the dash/cluster and that makes it particularly challenging to troubleshoot the system. To pay a Cadillac dealer to track down dash problems will most likely cost a prince's ransom. Fortunately, there are onboard diagnostics you can access that may aid in pinpointing some problems. To access the diagnostic mode turn the ignition to "on" and hold the "Off" and "Warm" buttons down simultaneously for a few seconds. Initially, ALL the lights in the cluster will illuminate (test mode) then it will go into the diagnostics mode. Record the trouble codes if any. Maybe someone would like to post the codes and what they mean. Pressing "auto" will take you out of the trouble-code display mode.

Basically on mine, the trouble codes didn't do me any good. My neighbor who has worked as a mechanic at Cadillac for 15 years says they don't often point ya to the problem, in his experience. To pinpoint the problem I resorted to an old trick electronic repair technicians use that involves careful use of a hair dryer and freeze spray. This strategy works on the principal that the majority of electronics failures are due to poor solder joints (cold joints), and leaky or dried-up electrolytic capacitors. This is an ideal trick for uncovering intermittant failures.

Getting Started:
I started out with my PCM. I removed all the shielding and heated the circuit board up with a hair dryer while the car was running. I was not able to make the dash flicker or go blank this way. When the dash did go blank after some time (like usual), I used freeze spray (abailable at www.partsexpress.com) to chill sections of the board and observing the effects on the dash. Chilling board or components on the board had no apparent bearing on the dash problem. Of course I wiggled connections and all that too, to no avail. I put it back together and moved on.

Next I inspected the connections for the aforementioned computer modules which, in a 92 Seville, are located in the trunk behind the back seat. Nothing I did back there seemed to have any relavence on the blanked-out dash (or made it flicker when it was actually working). I moved to the last thing, the IPC - Cluster. I removed the A-pillar covers, then the dash pad to reveal the cluster. Then I drove the vehilce until the IPC would flicker or blank-out as usual. When the dash would go blank I shot freeze spray through a hole in one end, watched observed the effects, then did the same to the other side. I was able to consistantly make the dash lights and gauges work properly with this method. At this point, I knew the problem lie in the cluster electronics. Time to dig a little deeper.

Working on the cluster:
I pulled the IPC from the car [see notes below] and very carefully removed all circuit boards from the cluster housing, and taped them to a 3' wooden board with masking tape (to hold the boards from sliding around). I transferred the whole assembly back to the vehicle, plugged it into the harnass and started the car. Now that I had all boards laying out in the open in front of me I could do some real diagnosing. I went around with the hair dryer, one section at a time keeping my eye on the dash for any flickering. I worked section by section. Eventually I heated up an area that would consistantly cause the dash to blank-out. Shooting freeze spray in that area would make it operate properly again. I was expecting the problem to be a bad capacitor. But there were no capacitors in this area.

Investigating further, I tapped around the region with my finger [be sure to discharge static from your body beforehand, or wear a wrist strap]. Everytime I tapped one corner of one of a particular processor-style chip the dash would cut out (go blank). I barely had to touch the corner. It was unmistakably consistant. I narrowed it down further to one pin on that microchip. Touch that pin [with a plastic instrument] it would go blank or flicker.

Making the repair:
I moved the whole dash assembly taped onto the 3' board into the shop and prepared to resolder that pin. Before soldering, I carefully chipped the clear circuit board protective spray coating (prevent's condensation problems) away from that portion of the chip. I carefully resoldered not applying too much heat (which could damage the microchip) and connected the dash to the car again. I was not able to make it "blank out" again. I heated the all circuit boards again with the hair dryer and was not able to get the dash to go out. Interestingly, the chip I resoldered resides next to the power regulator heat-sink (behind the HVAC Controls) when installed in the cluster housing. The heat produced by the regulator would cause a minor amount of expansion which would move the poorly soldered joint enough to break the power connection and cause the dash to blank-out.

The repair has been a success so far. So, guys, there you have it - an example of how a specific oft-used electronic trouble-shooting technique was used to isolate and resolve a pesky digital cluster problem. It only took me about 15 minutes to locate the problem once I got the dash dissassembled.


Other things to look at:
There are a bunch of electrolytic capacitors and what looks like a switching or regulating transistor on the power regulating portion of the cluster (behind the A/C controls). I can see how these could be a source of cluster problems that one would want to investigate in the course of a digital dash diagnosis. Capacitors often leak and/or dry up over time. These are high quality capacitors but 10 years is a long time for these and cars get hot in the summer. Look for leaky or bulging (tops) features. They could easily be unsoldered and replaced if found to be faulty (capacitors are marked for size and capacity). Newark is a good place to buy replacements electronic parts.

Hope this helps. Please share your tips and experiences.

Mark G

**IMPORTANT**----------------------------------------------------------
1) Before working on your dash, remove your air bag (SIR) fuse and unplug the yellow connector below your steering column.

2) Always be SURE to discharge static from your body before messing with any electronics or your car's Air Bag, SIR system. Wear a wrist strap or just tie some wire to your arm and ground it at the other end. You can never be too careful.

3) Remove the IPC fuses in the trunk before removing your dash. Reinstall after hooking your dash back up.

4) This is an example of a repair I made. The techniques used may not necessarily resolve your problems. Any repair attempts are made at your own risk :disappoin
 
See less See more
#27 ·
Re: Digital Dash Repair Tips - Ideas how to resolve speedometer and cluster problems

2000 Deville. Just had the engine replaced not the digital temp gauge is not working. All other parts of the digital dash are working. PLEASE HELP!!! I don't want the engine to overheat and have to buy another engine!!
 
#30 · (Edited)
I just had the same problem with the digital cluster on my '96 Fleetwood Brougham. I bought this car 12 yrs ago and it's been very reliable. The problem with the digital cluster started about 4 years ago, it would go blank once a week and I would tap on it and it would come back with no problem, but in the last few months it would go blank more and more and I had to tap on it more and harder to make it come back until this week, it stopped working. I took it apart and I powered up the big green circuit board and I started pushing or moving gently the pieces on the green circuit board but nothing happened. When I got to the tan mini circuit board and I gently pushed or pulled on the blue part with "3064" printed on the top of it, the display came back to life. I noticed that pulling on it was more effective than pushing it. What I did was, I put a little plastic wedge between the big green circuit board and the tan mini circuit board to lift up the mini circuit board about an 1/32 or 1/16th of an inch just enough to make the display come back. So far, it's working.
Electronics Technology Electronic component Hardware programmer Electronic device
 
#31 ·
I just had the same problem with the digital cluster on my '96 Fleetwood Brougham. I bought this car 12 yrs ago and it's been very reliable. The problem with the digital cluster started about 4 years ago, it would go blank once a week and I would tap on it and it would come back with no problem, but in the last few months it would go blank more and more and I had to tap on it more and harder to make it come back until this week, it stopped working. I took it apart and I powered up the big green circuit board and I started pushing or moving gently the pieces on the green circuit board but nothing happened. When I got to the tan mini circuit board and I gently pushed or pulled on the blue part with "3064" printed on the top of it, the display came back to life. I noticed that pulling on it was more effective than pushing it. What I did was, I put a little plastic wedge between the big green circuit board and the tan mini circuit board to lift up the mini circuit board about an 1/32 or 1/16th of an inch just enough to make the display come back. So far, it's working. View attachment 590458
Hi, how did you powered the big green circuit? I have a Seville from 1989 and also have the repair manual but i didn't figure it out yet. I also have flickering totally random on the dash, only the dash.
Thank you
 
#33 ·
Your 99 has pretty much zero in common with pre 94 so anything posts above does not apply.

Bcm has very little to do with anything IPC wise. You can run without one even.
Th ese are extremely picky about grounds so always check and clean those first.
A used bcm is plug and play, i wouldn't have bought new as they are not a known issue and used work just as fine. Multiple numbers will work.
Blower and hvac portion of ipc is controlled by ACM module under pass dash.
Usually when a blower on these goes full on its th e blower but not always. Real bitch to replace and get OEM as aftermarket are bad designs. So pray it's not th e issue. Fun fact... Blower will not run at all if vehicle isn't running(i test used ones all the time).
When weird things happen on these usually is a result of grounds being bad, yes they are that picky unfortunately.
IPC and ACM grounds are in kick panels.

If the car runs and display is blank the display portion from a donor can be swapped on without reprogramming needed. 94 to 99 should work although the pre 97 look different externally.
Bcm has nothing to do with center dash not being on.
Takes a couple of hrs to r&r an IPC on this era. You cannot just swap IPC or it won't run as IPC stores vats and vin, this is why you just use the display portion NOT the boards.

You migh t want to start a new thread or 3 breaking down your issues, Google search is much better at searching these forums than th e buikt in search engine.

Good luck
 
#34 ·
Your 99 has pretty much zero in common with pre 94 so anything posts above does not apply.

Bcm has very little to do with anything IPC wise. You can run without one even.
Th ese are extremely picky about grounds so always check and clean those first.
A used bcm is plug and play, i wouldn't have bought new as they are not a known issue and used work just as fine. Multiple numbers will work.
Blower and hvac portion of ipc is controlled by ACM module under pass dash.
Usually when a blower on these goes full on its th e blower but not always. Real bitch to replace and get OEM as aftermarket are bad designs. So pray it's not th e issue. Fun fact... Blower will not run at all if vehicle isn't running(i test used ones all the time).
When weird things happen on these usually is a result of grounds being bad, yes they are that picky unfortunately.
IPC and ACM grounds are in kick panels.

If the car runs and display is blank the display portion from a donor can be swapped on without reprogramming needed. 94 to 99 should work although the pre 97 look different externally.
Bcm has nothing to do with center dash not being on.
Takes a couple of hrs to r&r an IPC on this era. You cannot just swap IPC or it won't run as IPC stores vats and vin, this is why you just use the display portion NOT the boards.

You migh t want to start a new thread or 3 breaking down your issues, Google search is much better at searching these forums than th e buikt in search engine.

Good luck
Thanks for info!
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top