GM code E30

Old 02-26-04, 10:17 AM
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Question GM code E30

The vehicle is a 1989 Cadillac Fleetwood FWD, 4.5L v8. The cars idle revs up and down, so I pulled up the codes and it showed a code E30. The Haynes manual states:" Idle Speed Control (ISC) motor rpm out of range" What exactly does that mean? Is the rpm the manual is talking about the rpm of the engine or the rpm of the actual ISC motor?
Old 02-26-04, 10:56 AM
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e30... an ISC error code...the ecm has commanded the isc motor to make a correction in the idle speed and that action wasn't completed correctly. two things...mostly they had alot of trouble with the ISC motor getting all funky inside and then the motor wouldn't run in and out fact, they would get if you hear a squawk noise when you turn the key off, that ISC motor (mounted on the side of the throttle body) is probably bad. I have had success in taking them apart and cleaning/lubricating them and they used to sell the gear kits for them but I don't know if that is still available. you can also buy them reman from just about any parts store.

they also had problems with distributor gears wearing and causing unstable idle which in turn would set the E30...if you were to remove the distributor and look at the drive gear, it's obvious that it's messed up...the teeth will be very thin.

one other thing is that the idle adjustments are critical and VERY specific so don't go turning the plunger screw or the minimum idle speed screw as you will definately cause more problems and codes...a service maunual details the procedures
Old 02-28-04, 12:28 AM
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Thumbs up Thank You

Thank you very much. Your post was well writen, informative and to the point unlike some of the other forums I've been to. Once again Thank You.

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