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Cadillac Repair/92 Seville defrost comes on and gauges go blank.

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Expert: - 7/11/2011


Question
Hi,

My name is Tom and I have this exact problem (listed below) with my 1992 Seville.  I pasted the information from the original thread below.  Please help me determine the location of the most common "communication error" between the IPC and the PCM.  I can't find anyone, including the Cadillac Dealer, that knows anything about this failure.  Sometimes the OBD1 codes are present, and sometimes there are no codes.  What is the most common cause of a communication failure between these two components?  When the system fails, there is no ECM information, yet the engine runs fine!  While this event is happening, the dash control for the a/c, heating, defrost, climate control and estimated mileage show " -- ".  This problem occurs primarilly in cooler weather or at night.  The "Twilight Sentinel" stopped working before this problem started to occur more often, but I can't find any blown fuses or disconnected vaccuum hoses.  Please HELP ME.  I am a motorcycle mechanic, but this problem is not like anything that would occur on a bike.  Thank you so much!  Sincerely,

Tom Wolf

(760) 270-4515

QUESTION: all my dash information goes to -- , and my defrost locks on high and wont shut off. tried restarting car; pushed every button in car.  Also nothing blows out the vents, but I can hear blower running.. help!

ANSWER: Do you have an ANALOG or DIGITAL display ?.
EXACTLY what components show -- ?.
If you can video tape your problems e-mail the video to me at:

---------- FOLLOW-UP ----------

QUESTION: i have a analog dash but the right and left side have digital components.  left is my avg gas /avg mpg and information bottons.. right side is my outside/inside temp n temp controls. as i said those mentioned digital controls go to dashes (--) and the defrost locks on hi and wont turn off. i lose control of the dash functions, basically.  speedometer/rpm still works fine cuz its analog.  sometimes it resets back to normal within a few minutes, sometimes it stays like that for awhile.  it does not affect the cars driving at all just very annoying. sometimes after it resets it says service supplemental air restraint.  is that a sensor related to my airbag? how/why would that affect my dash controls?  (p.s. i just bought the car 2 months ago. only major thing done by me was replacing exhaust manifold gaskets and two new O2  sensors.)

Answer
I assume that your CLIMATE CONTROL PANEL WORKS.
1. Turn ignition ON.
2. Simultaneously push and hold the OFF and WARMER buttons for 2 seconds and the whole display will illuminate at which time you release the buttons.
3. Diagnostic codes will start to appaer as a LETTER and a number (ex: P123 or I32 or some other combination and will stop at either ECM? or PCM?
4. write down the letter/number combinations EXACTLY as if you were video taping them. If you can video tape them, E-mail to me at: .
If you lose track writing down the letter/numbers, simply push the AUTO button, turn OFF the key, Wait 30 seconds and start again at # 1 above.
What you have is a communications error between the instrument cluster and the PCM (computer).
We will deal with the air bag later.

Answer
Hello,

This was from another expert an the problem is that I don't know who. If you repost, I will get it put into the question bank being out of my expertise and maybe the guy that wrote this can follow up with you.

Good luck!

http://www.autotheftexpert.com

Cadillac Repair

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Rob Painter

Expertise

Alarm system questions cannot be answered on this forum. These systems are not what I can answer. Without being physically at the vehicle and not knowing what kind of electrical service has been done on the vehicle, there is no possible way to give an accurate answer over the internet. My expertise is in Ignition/key based anti-theft systems. These issues include GM VATS (resistor chip in key blade) PASSLOCK (MRD)-ignition lock rotation based, no special ignition key and the PKIII Transponder (computer chip in key) systems. These systems are not alarm based and are integral with the starting of the engine. This is why I cannot diagnose alarm problems without physically looking at the vehicle: Alarm systems are a completely different annimal than ignition key/lock based anti-theft system. Many alarm questions come from vehicles 10 years old, and since older, many hands that had been involved over the years.I am an expert in all GM factory (ignition/key based)systems. Alarm system questions pose to many situations beyond my knowledge as to what has been done to the vehicle over the years. Some guy may have actually wired the stereo into the alarm system. Who knows? Over my past 30 years in vehicle wiring repair, I have seen unbelievable wiring disaters done by guys that consider themselves "mechanics." I have seen stereos and alarms intalled using surgical tape. I have seen modules burn up, un-fused circuits, wiring jambed between the doors and even lamp cord used for a starter kill. To answer alarm questions over the internet without examining the vehicle is like asking; What does it take to remove a dent?

Experience

Education/Credentials-ASE certified. 11 years with a GM dealer and 17 years with a repair facility dealing with only the repair of theft recovered vehicles.

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