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1993 deville acceleration problem


CRASHSK8R

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I have a 1993 sedan deville with the v8 northstar engine. THe problem is that when we start the car it idles at a very high speed and also when driving it will accelerate by itself. it also seems to guzzle gas. I am reading error codes 30, 40, 92, 52. is it maybe gunk in the ISC or throttle body, or would a vaccum problem be it.

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I have a 1993 sedan deville with the v8 northstar engine. THe problem is that when we start the car it idles at a very high speed and also when driving it will accelerate by itself. it also seems to guzzle gas. I am reading error codes 30, 40, 92, 52. is it maybe gunk in the ISC or throttle body, or would a vaccum problem be it.

The 93 Deville has the 4.9 OHV Engine not the Northstar

Here is a little history on the car

http://www.motorera.com/cadillac/cad1990/CAD93D.HTM

Find your codes under ECM here

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

P030 (E030) ................................................... ISC RPM out of range

P040 (E040) .................................... Power steering Pressure switch open

P052 (E052) ....................................................... PCM Memory Reset

P092 (E092) ...................................... Heated Windshield Request Problem

You can also click How To at the top of this page, go to DTC Codes and click Trouble Codes by system.

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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As you can see above, you are getting an ISC code

I had a 91 Seville and never had problems with the idle system including the ISC. But from what I understand the ISC or Idle Speed Control has contacts that close when the throttle is closed, I believe when those contacts close it signals the ISC to retract. if those contacts are dirty or worn, your ISC may not be retracting.

There is a lot of information on ISC motors here, if you do a search. Barry94 did a great thread where he explained how the ISC works and how to clean those contacts. Here is a link

http://caddyinfo.ipbhost.com/index.php?showtopic=7605

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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As you can see above, you are getting an ISC code

I had a 91 Seville and never had problems with the idle system including the ISC. But from what I understand the ISC or Idle Speed Control has contacts that close when the throttle is closed, I believe when those contacts close it signals the ISC to retract. if those contacts are dirty or worn, your ISC may not be retracting.

There is a lot of information on ISC motors here, if you do a search. Barry94 did a great thread where he explained how the ISC works and how to clean those contacts. Here is a link

http://caddyinfo.ipbhost.com/index.php?showtopic=7605

Thank you for the info and the link. i am new to the forum as well as cadillac cars. I will check out the link and i hope i can use it . When i bought the car it had the error code for the power steering pressure switch but the fluid level is always full. the guy told me it was the sensor telling the car it was empty or low is that an accurate assesment? and as for the heated windsheild i have a cracked windsheild and i think it is cutting off continuity in the cunductive paint.

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As you can see above, you are getting an ISC code

I had a 91 Seville and never had problems with the idle system including the ISC. But from what I understand the ISC or Idle Speed Control has contacts that close when the throttle is closed, I believe when those contacts close it signals the ISC to retract. if those contacts are dirty or worn, your ISC may not be retracting.

There is a lot of information on ISC motors here, if you do a search. Barry94 did a great thread where he explained how the ISC works and how to clean those contacts. Here is a link

http://caddyinfo.ipbhost.com/index.php?showtopic=7605

Thank you for the info and the link. i am new to the forum as well as cadillac cars. I will check out the link and i hope i can use it . When i bought the car it had the error code for the power steering pressure switch but the fluid level is always full. the guy told me it was the sensor telling the car it was empty or low is that an accurate assesment? and as for the heated windsheild i have a cracked windsheild and i think it is cutting off continuity in the cunductive paint.

There is a pressure switch mounted on the steering rack under the car. That is the switch that is setting the code.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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As you can see above, you are getting an ISC code

I had a 91 Seville and never had problems with the idle system including the ISC. But from what I understand the ISC or Idle Speed Control has contacts that close when the throttle is closed, I believe when those contacts close it signals the ISC to retract. if those contacts are dirty or worn, your ISC may not be retracting.

There is a lot of information on ISC motors here, if you do a search. Barry94 did a great thread where he explained how the ISC works and how to clean those contacts. Here is a link

http://caddyinfo.ipbhost.com/index.php?showtopic=7605

Thank you for the info and the link. i am new to the forum as well as cadillac cars. I will check out the link and i hope i can use it . When i bought the car it had the error code for the power steering pressure switch but the fluid level is always full. the guy told me it was the sensor telling the car it was empty or low is that an accurate assesment? and as for the heated windsheild i have a cracked windsheild and i think it is cutting off continuity in the cunductive paint.

There is a pressure switch mounted on the steering rack under the car. That is the switch that is setting the code.

so the error code for the power steering pressure switch is not about the fluid level in the resevoir, it means that i could have a power steering problem or is it maybe the sensor?

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The code is stating the switch is OPEN. That can mean that the sensor switch is BAD or the connector is off of it. That should be an easy fix.

This is not related to fluid level, its probably related to the speed sensitive steering circuit

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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The code is stating the switch is OPEN. That can mean that the sensor switch is BAD or the connector is off of it. That should be an easy fix.

This is not related to fluid level, its probably related to the speed sensitive steering circuit

thank you for the info also i wanted to know about the bolt the comes out from the ISC and contacts the throttle cable. am i able to adjust in or outward to maybe adjust the idle or is that something that is set to a specific spot already. it looks a little farther outward than the ones in the picture of my hanes book and i wondered if that could be it. thank you

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The code is stating the switch is OPEN. That can mean that the sensor switch is BAD or the connector is off of it. That should be an easy fix.

This is not related to fluid level, its probably related to the speed sensitive steering circuit

thank you for the info also i wanted to know about the bolt the comes out from the ISC and contacts the throttle cable. am i able to adjust in or outward to maybe adjust the idle or is that something that is set to a specific spot already. it looks a little farther outward than the ones in the picture of my hanes book and i wondered if that could be it. thank you

I will leave this to someone else, I always did the detailed adjustment method, there is a quick method to adjust it, I think Ranger knows it

Is it clicking when you turn your key off?

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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To adjust the ISC plunger, press in on it. It should retract and the RPM will fall to about 450 or may even stall. When it is fully retracted, pull the electrical connector. Now adjust the plunger to a .060 gap with the throttle lever. It is now adjusted correctly. Plug it back in and see if that helps, but they rarely get out of adjustment.

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