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1993 4.9 Deville new to me code E30


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Just got a  light on (service soon ) E030) ...................................................  ISC RPM out of range I am about to try to look it up in the service manual hope it is not much as I am about to put the car away fro winter I about 6 weeks

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This OBD I DTC is equivalent to the two OBD II DTC's P0506 and P0507, which tell whether the idle speed is low or high.  The limits for setting the DTC in the 1997 FSM is 80 RPM.  The PCM is designed to control the idle speed within 50 RPM.

The 1997 FSM says to fix problems flagged by other DTC's before looking at P0506/0507.  In particular, a noisy power steering pressure switch can case a P0507 to be thrown.

The troubleshooting chart in the 1997 FSM says to check, in this order, the electrical connections to the IAC valve (particularly the connector), clean the IAC valve, check for "tampering" with the throttle body adjustment screws, obstructions in the intake system including clogged air cleaner element, collapsed intake duct, etc., and dirty or obstructed throttle body.

The next step in the 1997 FSM is, if everything is clean and unobstructed and you still get code returning chronically or CURRENT, to replace the IAC valve.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Trying to diagnose a '93 car with a '97 shop manual is not going to be much help.  The '93 has the idle speed control motor where the Northstar cars have the idle air control system.  There is a ton of information n the archives on the idle speed control system.

If the car is idling high, the prime suspect is the closed throttle contacts within the idle speed control motor.  There is a way to check this from the onboard diagnostics - search "Idle Speed Control" or ISC on the forum search page.

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

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Thanks fpr fixing this.  I was trying to give a timely response.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Here is an old post from when my name was Scotty, 12 years ago :blink: wow

 

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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Make sure the throttle plate and the throttle bore is clean. Pull the throttle body and clean it if it is not. Use Carb cleaner on a rag for cleaning and rinse with brake cleaner. Carb cleaner leaves a residue brake clean does not.

Rev the engine and watch the ISC motor rod, it should operate outward smoothly and retract smoothly as well,

If I remember correctly you have a FSM, If not the diagram should help you to drive the ISC from the diag panel....

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THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Yes I have a manual thanks OldCadTech I have been having trouble getting the time to work on it. Actually I did clean the throttle body about a month ago I will get at it soon and report back   

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Do you hear the ISC clicking?  The gears go bad, and will click.  I have some photos of what it looks like in the thread below.  I replaced it with a Standard Motor Parts unit, because they were selling the car.  I have never heard problems with AC DELCO (oem) as Dan noted, if it were my car, I would use AC DELCO.  Standard has always been a quality product though.

I just had the same problem on a 95 Eldo, racing idle.  Here is my most recent ISC issue.  Click the link below to go to the August thread regarding my replacing the ISC.

 

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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@red-oak 

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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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