Erratic Gauges and CCP, IPC, and DIC

[MarineOne]

I have a 1992 Cadillac Seville STS. My dash lights and displays will be on and suddenly go out, then almost immediately come back on. Sometimes this resets my trip odometer, and sometimes, when the dash lights come back on, the electronic climate control turns on the AUTO function on the A/C. The gas gauge, speedo and tach all die at the same time as the lights, and come back just as quickly. The radio clock/station display also goes out. Sometimes they will all work for a few minutes then turn off completly and the defrost will turn on afterward. Also, when the lights come on, I get random DTCs like "service vehicle soon, check fuel gauge, a/c coolant low", and some others. My "service engine soon" light has come on once during this, and then gone out 2 minutes later. Sometimes I will loose the function of just one of the gauges for a few minutes, and then it will come back and function normally. I checked all the fuses under the hood and in the trunk as well as checked a few ground wires and relays. While all of this is happening, it doesn't seem to affect the drivability of the car, yet. It seems to me like there is a short somewhere, but I don't know where to start. Also, I have checked the Diagnostic codes, and they are all HISTORY codes, nothing CURRENT. Is there anything else I can do myself before I have to take it to the dealer and pay them to fix it?

[BodybyFisher]

Post the history codes, there should be a clue there

[CarlaValentine]

Even if they are history codes, you should still post them and consider them as probable cause to your issues. History only means that the code was not set since the last time the ignition was turned on, meaning it could be from you parking your car 5 minutes ago, but it's not there when you start it now. Codes would be a very good place to start.

When you checked the fuses, did you notice any kind of moisture or corrosion on or anywhere near the fuses or the fuse panels? Both of these can cause problems with the electrical signals. Also check under and around your dash and IPC for any moisture or water.

You should also check your battery cables to make sure they are securely connected and free of any corrosion. These cars NEED a good battery connection. I have had this stressed to me many times over. If you can access your voltage reading on the driver information center while the car is running, you should check to be sure it is within normal range as well. Normal range should be between about 13.8 and 14.5 (according to my manual).

I would really start with rechecking your codes and posting them here though.

[MarineOne]

I will get the trouble codes later today after work and post them ASAP. I don't remember seeing any moisture in the fuses, but that is not to say that there wasn't any. I'll check again. Also, the battery voltage is normal, 14.1. I did recently put di-electric grease on my neg battery terminal, to inhibit corrosion, and also cleaned my fuse panel under the hood. I put everything back in (fuses and circuit breakers) exactly how they came out. I don't see how it would affect the vehicle negatively to clean electrical connections?

[CarlaValentine]

Quote

"I don't see how it would affect the vehicle negatively to clean electrical connections?"

It wouldn't unless you damaged something in the process, but as long as you are careful, then that's pretty unlikely.

Was this happening prior to you cleaning everything? Or did it start happening after that?

[MarineOne]

After...

[CarlaValentine]

Then I would say there's a good chance something got messed up in the process of you cleaning everything.

Start by running your DTC's and posting them, as mentioned before.

How and with what did you clean everything?

[MarineOne]

Trouble codes are as follows, Verbatum:

E047H

E052H

E091H

I022H

I039H, the second time i ran it, it was I039C

I052H

I056H

NO ACP CODES

R033H

ECM?

[CarlaValentine]

E047= IPC - PCM data problem (there is a communication problem between your IPC and your PCM. This seems a likely culprit for your problems)

E052= PCM memory reset (this will happen any time you disconnect your battery or pull the PCM fuse)

E091= PRNDL switch problem (trans-axle range switch problem)

I022= Panel dimming switch pot circuit (something is causing a problem with your dash light dimmer switch)

I039= Loss of Road Sensing Suspension Data

I052= Keep alive memory error

I056= Instrument panel cluster EEPROM error (I believe this is a PCM related problem)

R033= Steering diode shorted in Arming sensor

ECM?= your car displays this after displaying all codes. This is your Diagnostics Data display mode.

I am going to make an educated guess based on what I am seeing here and say that I believe there is something wrong with your PCM. I am also going to say that I personally don't believe just replacing it will solve your problems unless you can figure out what screwed it up in the first place. I wish I could give you a place to start looking for problems, but I'm really not sure. It's hard for me to say without knowing exactly what you did when you were cleaning everything. If you can, try to give as good a description as possible.

I hope someone else will chime in on this with something a little more helpful. I have given all the information I can think of off the top of my head.

[MarineOne]

Ok, here is as much as i can remember about what i did when I cleaned everything; I took all fuses and circut breakers out of their respective positions, sprayed the fuses and breakers with electrical contact cleaner, sprayed the fuse blocks with the same, waited for the cleaner to dry, then sprayed a coat of silicone di-electric grease on the fuse block contacts for all terminals. I did this for the fuse block in the engine bay, as well as for the few fuses and circut breakers i could reach under the main one in the engine bay. I didn't disassemble much because i am still new with this vehicle and would like to get more familiar with it before i do any serious disassembly of components. I didn't notice any moisture in the fuses/breakers, but that isn't to say there wasn't any; i wasn't looking for it. The only other maintenance I did was change out the distributor, rotor, coil, wires, and plugs with new ones. But that makes the vehicle itself run better than it did before, which leads me to believe it is not the cause of the current problem... I believe that the main problem is either a short on the power supply side of the dash/display console, or a short in the common ground for the same. The problem is, I don't know where to look for either one... Does this guess about the problem seem heading in the correct direction?

[CarlaValentine]

Ok, here is as much as i can remember about what i did when I cleaned everything; I took all fuses and circut breakers out of their respective positions, sprayed the fuses and breakers with electrical contact cleaner, sprayed the fuse blocks with the same, waited for the cleaner to dry, then sprayed a coat of silicone di-electric grease on the fuse block contacts for all terminals. I did this for the fuse block in the engine bay, as well as for the few fuses and circut breakers i could reach under the main one in the engine bay. I didn't disassemble much because i am still new with this vehicle and would like to get more familiar with it before i do any serious disassembly of components. I didn't notice any moisture in the fuses/breakers, but that isn't to say there wasn't any; i wasn't looking for it. The only other maintenance I did was change out the distributor, rotor, coil, wires, and plugs with new ones. But that makes the vehicle itself run better than it did before, which leads me to believe it is not the cause of the current problem... I believe that the main problem is either a short on the power supply side of the dash/display console, or a short in the common ground for the same. The problem is, I don't know where to look for either one... Does this guess about the problem seem heading in the correct direction?

Did you disconnect the battery before you sprayed everything with contact cleaner?

[MarineOne]

Ok, here is as much as i can remember about what i did when I cleaned everything; I took all fuses and circut breakers out of their respective positions, sprayed the fuses and breakers with electrical contact cleaner, sprayed the fuse blocks with the same, waited for the cleaner to dry, then sprayed a coat of silicone di-electric grease on the fuse block contacts for all terminals. I did this for the fuse block in the engine bay, as well as for the few fuses and circut breakers i could reach under the main one in the engine bay. I didn't disassemble much because i am still new with this vehicle and would like to get more familiar with it before i do any serious disassembly of components. I didn't notice any moisture in the fuses/breakers, but that isn't to say there wasn't any; i wasn't looking for it. The only other maintenance I did was change out the distributor, rotor, coil, wires, and plugs with new ones. But that makes the vehicle itself run better than it did before, which leads me to believe it is not the cause of the current problem... I believe that the main problem is either a short on the power supply side of the dash/display console, or a short in the common ground for the same. The problem is, I don't know where to look for either one... Does this guess about the problem seem heading in the correct direction?

Did you disconnect the battery before you sprayed everything with contact cleaner?

Yes, I disconnected the battery.

[CarlaValentine]

After doing some thinking and some research, I think I may have found your problem.

Dielectric grease is intended for SEALING electrical connections and protecting them from moisture and corrosion. It is, for the most part, non-conductive. By spraying this on your fuse block contacts, you have essentially made them non-conductive.

As far as finding a solution for cleaning it out, I'm still working on that one. I will let you know if and when I come up with something.

Also, another question. You said, "The only other maintenance I did was change out the distributor, rotor, coil, wires, and plugs with new ones."

Most cars I have seen have either a Distributor and rotor, OR a coil, but not both. Are you really sure your car has all 3?

[CarlaValentine]

After doing some thinking and some research, I think I may have found your problem.

Dielectric grease is intended for SEALING electrical connections and protecting them from moisture and corrosion. It is, for the most part, non-conductive. By spraying this on your fuse block contacts, you have essentially made them non-conductive.

As far as finding a solution for cleaning it out, I'm still working on that one. I will let you know if and when I come up with something.

Also, another question. You said, "The only other maintenance I did was change out the distributor, rotor, coil, wires, and plugs with new ones."

Most cars I have seen have either a Distributor and rotor, OR a coil, but not both. Are you really sure your car has all 3?

I assumed when posting this, that you sprayed the dielectric grease on the fuse panels while you had the fuses removed. If so, then that is most likely the problem. If the fuses were in the panel when you sprayed it, then it may not be. I apologize for assuming.

If my assumption is correct however, the only thing I have come up with for cleaning them is to pull the fuses and wipe the grease off them with a cloth or rag, and try to wipe what you can out of the fuse panel. If you can't get all of it, it shouldn't be too big a deal. When you put the fuses back in they should be able to make a good contact as long as there is a minimal amount of the grease for them to have to "break through" to get a good connection.

[MarineOne]

After doing some thinking and some research, I think I may have found your problem.

Dielectric grease is intended for SEALING electrical connections and protecting them from moisture and corrosion. It is, for the most part, non-conductive. By spraying this on your fuse block contacts, you have essentially made them non-conductive.

As far as finding a solution for cleaning it out, I'm still working on that one. I will let you know if and when I come up with something.

Also, another question. You said, "The only other maintenance I did was change out the distributor, rotor, coil, wires, and plugs with new ones."

Most cars I have seen have either a Distributor and rotor, OR a coil, but not both. Are you really sure your car has all 3?

If that is indeed the problem, I can just re-spray the di-electric cleaner with MAF sensor cleaner, it will remove the grease. As for the distributor, rotor and coil; by coil I mean the ignition coil that sits inside the top portion of the distributor cap. As you know, my vehicle does not use ignition coils like on later model vehicles. Thanks for the help so far, I will clean off everything (again) after work and will post the results!

[BodybyFisher]

I have never seen dielectric grease cause a problem, I doubt that is it. I found this at Klein Tools site

• Moisture-proof seal for aircraft,

automotive and marine ignition

systems and spark plug connections.

• Use on waterproof electrical

connections, electrical assemblies

and terminals.

• Acts as a sealant and lubricant for

cable connectors, battery terminals,

rubber door seals, rubber and

plastic O-rings.

I found it recommended for all electrical connections on a 60s Triumph to keep moisture out of the connectors a car notorious for electrical problems.

Now I realize its non conductive, but as long as the connection is sound, it should not make a difference, it will just moisture proof the connection and reduce the chances of corrosion

Did any of your fuses or relays have corrosion when you cleaned them. And how did you clean them, MAF cleaner?

You need to list the systems that are affected then go to electrical schematic and see if the systems share a common ground, its possible that the ground needs cleaning / tightening etc. The 92 has been known to have issues with grounds.

Put together a list of systems affected and see if there is a common ground or feed circuit. I trust the battery and battery connections are solid.

Someone here should be able to help you with electrical info from a 92. I have a 91 manual and will have a look at it. One question is that a digital dash?, my 91 had a digital dash. Here is a chart showing ground locations:

[CarlaValentine]

Quote

"by coil I mean the ignition coil that sits inside the top portion of the distributor cap"

Oops, yeah I forgot about that. Guess I'm just too used to coil referring to the coils on newer ignition systems.

[CarlaValentine]

I have never seen dielectric grease cause a problem, I doubt that is it. I found this at Klein Tools site

• Moisture-proof seal for aircraft,

automotive and marine ignition

systems and spark plug connections.

• Use on waterproof electrical

connections, electrical assemblies

and terminals.

• Acts as a sealant and lubricant for

cable connectors, battery terminals,

rubber door seals, rubber and

plastic O-rings.

I found it recommended for all electrical connections on a 60s Triumph to keep moisture out of the connectors a car notorious for electrical problems.

Now I realize its non conductive, but as long as the connection is sound, it should not make a difference, it will just moisture proof the connection and reduce the chances of corrosion

Did any of your fuses or relays have corrosion when you cleaned them. And how did you clean them, MAF cleaner?

You need to list the systems that are affected then go to electrical schematic and see if the systems share a common ground, its possible that the ground needs cleaning / tightening etc. The 92 has been known to have issues with grounds. Put together a list of systems affected and see if there is a common ground or feed circuit. I trust the batter and battery connections are solid. Someone here should be able to help you with electrical info from a 92. One question is that a digital dash?, my 91 had a digital dash. Here is a chart showing ground locations:

I agree that a bad ground could also be the problem here, but it was said that a coating of silicone dielectric grease was sprayed on the fuse block contacts for all terminals. A coating normally means quite a bit, and if any of the fuses don't fit good and tight into their connectors then this could create a conduction problem.

You are right though, he should also check all grounds.

[MarineOne]

Well, I re-cleaned all fuses and relays and circut breakers i had coated with di-electric grease. By clean i mean down to the bare metal. Spotless. Also cleaned the battery terminals. No dice. Actually, where my display used to show the odometer reading, it now says "Error". And I keep getting the message "Change Oil Soon", and then "Change Vehicle Oil", and sometimes "service immediately". But the car still runs great. No effect on performance what-so-ever. It was too dark to check all the grounds on the vehicle, and I can't figure out how to remove the rear passenger seats to get to the fuse box under them. Also, I've been searching for a post on how to clear the codes on the ECM, but can't find one. Does anyone know how to do it?? I am ready to say just replace the ECM, but if that isn't the source of the problem, I will have wasted time and money. Any more ideas??

[BodybyFisher]

Do you have a digital dash?, anotherwords how is your speed shown digitally or with an analog needle?

Also, give me a list of what systems are affected by this

Do NOT replace parts without proper diagnosis, parts replacing is a mistake

[MarineOne]

I have a digital dash (digital fuel milage, digital climate control, and digital message bar (you know, below the speedo and tach)). My speedo, tach, and fuel gauges are needles. When this problem occurs, EVERYTHING goes off. My entire dash shuts down and starts back up a second later. It also shuts off the radio display. Like I've said a million times though, it doesn't affect the drivability of the car. Also, this morning coming to work something new happened... when everything should have come back on after it flickered off, the display said "calibrating", then calibration failure", then the service engine soon light came on. Nothing else, no DIGITAL stuff worked. My speedo, tach and fuel gauge came on, but nothing else. While it was "calibrating" the tach, speedo, and fuel gauge were working as well. I pulled over, shut the car off, opened the door (to shut off the radio, just in case), started it back up, and it read "calibrating", then "calibration complete", then everything came on. This occured 3 times in a 30 minute drive. I am convinced it is either the common ground for the dash equipment, my dash cluster is fried, or my ECM is fried. What do you think?

[BodybyFisher]

Give me a couple of hours, Ill pull out my 91 service manual out of the garage, you are loosing power to that circuit either by a bad ground or power source. let me see if I can find anything in the manual. I dont think this is the ECM at all.

If its the dash cluster, there are places that rebuilt them, I had a digital dash go black on an 86 corvette. So from what you can see NOTHING else is affected, outside of the digital dash?

[MarineOne]

Give me a couple of hours, Ill pull out my 91 service manual out of the garage, you are loosing power to that circuit either by a bad ground or power source. let me see if I can find anything in the manual. I dont think this is the ECM at all.

If its the dash cluster, there are places that rebuilt them, I had a digital dash go black on an 86 corvette. So from what you can see NOTHING else is affected, outside of the digital dash?

The digital dash AND the gauges all go out at the same time, as well as the radio display.

[BodybyFisher]

I was just looking at these two codes that you reported:

E047= IPC - PCM data problem

E091= PRNDL switch problem (trans-axle range switch problem)

There is a dash to PCM connector, behind the dash.

Circuit 800B is the UART serial data and circuit if open 773 is related to the E091 PRNDL code

I would pull the digital dash, clean the connector and reseat it first, both of those circuit are in the Dash to PCM connector

I have my 91 manual now and should be able to help

[MarineOne]

I was just looking at these two codes that you reported:

E047= IPC - PCM data problem

E091= PRNDL switch problem (trans-axle range switch problem)

There is a dash to PCM connector, behind the dash.

Circuit 800B is the UART serial data and circuit if open 773 is related to the E091 PRNDL code

I would pull the digital dash, clean the connector and reseat it first, both of those circuit are in the Dash to PCM connector

I have my 91 manual now and should be able to help

Ok, i am pretty good when it comes to electrical stuff, but how can you tell which circut is which in the connector? And what is a UART? And is it absolutely neccessary to remove the entire dash, or is there a way to get to the connector without removing everything?