Hello

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My Car is a 1992 Cadillac Seville STS4.9L export version.

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The Problem: When I turn ignition on, the "SERVICE ENGINE SOON" lights up or sometimes flickers. The Problem occurs frequently not always. When the Car is running, the displayedtemperature goes very highup and down, enought to display "Engine Hot" "Idle Engine" and the Fan turns on. Inidlethe engine revolutions switch between 300 and 1500 rpm by itself. Sometimes it's not possible to turn the engine on (Starter works)

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Already done: checked engine coolant, checked codes, checked for leak, the car tries even with shut off engine to increase the rpms by accelerate like cruise control (CC is off)

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Codes: "E031 (Shortet MAP Sensor)" When it was possible to start the engine, some other codes appear: "E022 (Open TPS Signal [VCC])" "E037 (Shortet MAT Sensor Signal)" "E065 (Cruise - SPS Failure)" "E071 (Intermittent MAP Signal)" "E073 (Intermittent Coolant Sensor Signal)" "E074 (Intermittent MAT Signal)" "A050 (HVAC - Coolant Temperature Too High)" After shutting the engine off, these codes are saved as HISTORY, only E031 and E065 stay as CURRENT.

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I hope that's enough information, otherwise please ask. I need the car to go to work, please answer soon.
Thanks a lotfor your helpfulness.

 

I have found the problem:
i mesured the resistance of the MAP sensor (locatedright tothe alternator). Sometimes the values switched between 39Ω and over 140Ω. I guess because of that, the ECM calculated wrong values for ignition and injection.
I'll let you know, if the error appears again with a new MAP sensor.

 

Nice find, and thanks so much for posting the results. This could help many members here in the future.

G.A.R.Y.

 

HEY!! THIS IS INTERESTING??? MY 93 DEVILLE IS BASICLY DOING THE SAME,, BUT MINE AFFECTS THE CLIMATE CONTROL AND FUEL MANAGEMENT?? EVERY WORKS EXCEPT A/C AND GAS GUAGE.. EVERYTHING IS WORKING AND THEN BEGINS TO FLICKER AND IT LOOKS LIKE A PINBALL MACHINE!!!! ALL THAT REMAINS IS A SMALL ..c... IN THE GAS GAUGE SECTION AND THE CLIMATE CONTROL CENTER.... THEY SAY IT MIGHT BE MY BODY CONTROL MODULE?????? HELP !!!!!!!

 

Have you read the error codes in the onboard diagnostic?Please post them.

 

THANKS ...WHAT IS THE CORRECT WAY TO BRING UP CODES ..I TRIED IT DID NOT WORK????

 

Please check all ground. as a loose ground on the engine can cause all the codes you described. Also ECM are a common issue

 

i just know how to bring up codes at the seville but probably it works for deville too. you have to press and hold the two buttons: "Warmer"(just a red button)and "Off". after few seconds the codes appear. if there are no codes for a specific system it says for example: "NO ACP CODES" after all codes are through, it says "ECM?" to see the codes again just press off again. to leave the diagnostics system press "Auto".

 

My 93 caddy seville is starting to act a little weird, i did the whole check the code thing. i did get some codes but i cant find any where on line or here to tell me what the codes mean. can anyone please help point me in the right direction as to where i can find this info. thanks so much.

 

Here is the best site I know of:

http://myweb.accessus.net/~090/dtcobd1.html#pcm