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deville climate control problem


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I am having a issue with the climate controls. At first everything is great but after a moment the left and right side of the digital dash goes to dashes, and the defrost is stuck on high. I Installed a rebuilt ECM/PCM with no change at all.

I retrieved the following code from the climate control ( note the ECM/PCM will connect with my OTC scanner )

NO PCM DATA

CODE IO32 CURRENT ( Loss of ABS/TCS Data )

CODE IO34 CURRENT ( Loss of Powertrain Control Module Data )

CODE IO37 CURRENT ( Loss of Air Conditioning Programmer Data )

CODE IO39 CURRENT ( Loss of Road Sensing Suspension Data )

CODE IO52 HISTORY ( Keep Alive Memory Error )

NO ACP ( Air Conditioning Programmer )

NO SIR ( Not sure what this is )

NO TCS ( Traction control I believe )

PCM? ( Worried about this one )

Please Advise

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NO PCM DATA

CODE IO32 CURRENT ( Loss of ABS/TCS Data )

CODE IO34 CURRENT ( Loss of Powertrain Control Module Data )

CODE IO37 CURRENT ( Loss of Air Conditioning Programmer Data )

CODE IO39 CURRENT ( Loss of Road Sensing Suspension Data )

CODE IO52 HISTORY ( Keep Alive Memory Error )

NO ACP ( Air Conditioning Programmer )

NO SIR ( Not sure what this is )

NO TCS ( Traction control I believe )

PCM? ( Worried about this one )

SIR is your airbags. Supplemental Inflatable Restraints

PCM? is nothing to worry about. This is displayed after all the codes. It is for the PCM data and running further diagnostics.

Does the car still start, run and drive right? It sounds to me like the new PCM was not programmed properly when it was installed, as it appears to not be receiving data from most of your car's systems. I'm sure others will chime in on this one.

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Seen that before. Chances are it is a bad IPC. Classic failure mode, '--' and Defrost kicks into high.

All the computers 'talk' to each other on circuit 800 (tan). When one of the computers goes bad, it corupts the data on circuit 800, hence the '--' on the IPC display and multiple 'loss of data' codes.

You can measure circuit 800 at pin M on the ALDL. Should be 3-5 volts and changing all the time. If the voltage locks up, about 20 seconds latter the IPC display will go to '--', and then the warning messages will kick in.

You can unplug the computers one at a time to locate the bad one, while measuring voltage at pin M.

As mentioned, very common IPC failure mode. Problem is, Delco speedometer repair shops cannot 'see' this failure mode. In their test mode, '--' on the display is normal. Not uncommon to require 4-5 'rebuilt' IPC units to find a good one.

Luckly for you, it is a immediate failure. The real hard ones are the intermitant, every 500 mile ones.

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Logan, interesting that your bring up an intermittant IPC problem, this is a 92 but what do you think? thanks, Mike

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Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Fisher, on the 1992 STS he should clean the engine ground which is very near the starter on the 4.9 engines.

As for this post. This is a classic, well known, failure mode description FOR the '92-95 Seville and '94-95 Deville IPC ('--' display, defrost engaged, warning messages, mutiple 'loss of data' codes and display warnings). Sure it may be one of the other computers, but 95% of the time, it's a bad IPC.

No other years apply.

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The car runs like a champ no issues expect the controls. I have been looking for a BCM with no luck.

What is a IPC is it the Climate Control Computer. This was my next guess i have located it on the pass side in front of the PCM.

CarlaValentine mentioned the PCM was not programed correctly, it is a OBD I unit it takes a PROM module.

Does it still have to be programed?

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The car runs like a champ no issues expect the controls. I have been looking for a BCM with no luck.

What is a IPC is it the Climate Control Computer. This was my next guess i have located it on the pass side in front of the PCM.

CarlaValentine mentioned the PCM was not programed correctly, it is a OBD I unit it takes a PROM module.

Does it still have to be programed?

I just want to mention here that after reading what others had to say, I doubt it's a PCM issue. If it were then I don't think the car would be running right, if at all (I may be wrong here). Also, IPC is Instrument Panel Cluster. Personally, I would probably follow up on Logan's advice. He seems to be familiar with this issue.

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Fisher, on the 1992 STS he should clean the engine ground which is very near the starter on the 4.9 engines.

As for this post. This is a classic, well known, failure mode description FOR the '92-95 Seville and '94-95 Deville IPC ('--' display, defrost engaged, warning messages, mutiple 'loss of data' codes and display warnings). Sure it may be one of the other computers, but 95% of the time, it's a bad IPC.

No other years apply.

Thanks Logan, yes we have seen the ground create fits especailly on the 92 for some reason, but I have not seen it affect the IPC yet, thats great info. Thanks

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I looked at the CODE E047 the ALDL ties into the IPC and BCM (body control module). No doubt that the IPC is affecting the ALDL

As Logan noted, the IPC is at fault a lot

later Ill post a full breakdown of E047, it would be good to look over the diagnositic tips, Mike

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I can't believe it. The problem was the ALDL cover has a jumper madE into it and I must have knocked it off at some point and I never put it back on.

I took it to Cadillac, and after one hour a tech who has worked there for 26+ years showed it to me.

It cost me $100 at the DEALER!!!

The car is back to normal. Luck was on my side for once

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Very interesting, I dont think I ever heard this before, as a matter of fact, my ALDL cover was in my console on my 91, I never used it..very odd

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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  • 7 months later...

Seen that before. Chances are it is a bad IPC. Classic failure mode, '--' and Defrost kicks into high.

All the computers 'talk' to each other on circuit 800 (tan). When one of the computers goes bad, it corupts the data on circuit 800, hence the '--' on the IPC display and multiple 'loss of data' codes.

You can measure circuit 800 at pin M on the ALDL. Should be 3-5 volts and changing all the time. If the voltage locks up, about 20 seconds latter the IPC display will go to '--', and then the warning messages will kick in.

You can unplug the computers one at a time to locate the bad one, while measuring voltage at pin M.

As mentioned, very common IPC failure mode. Problem is, Delco speedometer repair shops cannot 'see' this failure mode. In their test mode, '--' on the display is normal. Not uncommon to require 4-5 'rebuilt' IPC units to find a good one.

Luckly for you, it is a immediate failure. The real hard ones are the intermitant, every 500 mile ones.

logan can you please go into more detail I am very new and guessing alot when it comes to these descriptions. the aldl is the plug that is under the dash I need to know which pin is m and also i am in need of knowin exactly what the ipc is.. I am guessing it is the complete dash including the computers to the left and right

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IPC (Instrument cluster panel)

centered with the steering wheel in the dash. /has the fuel computer and climatee control modules on it.

Very weird on the jumper deal but I have heard of it before. The jumper completes the circuit between all of the computers.

I am a bit rusty on this but I believe I have it right

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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There is another post nearby with the same problem..

A scan tool does no good on this problem.

That era of Cadillac should have a cover on the ALDL. Inside the cover is a jumper that completes the circuit 800 loop when plugged in.

Pin M on the ALDL is where the voltage on circuit 800 can be measured.

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