1994 Chevy Caprice aldl and idle

1994 CHEVROLET CAPRICE
130,000 MILES • V8 • 2WD • AUTOMATIC
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LUWILKES
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check engine wont come on when terminal a and b is shorted but come on if not shorted and switch is on(normal).And fast start up idle all the time which is the reason I was trying to get a code by shorting the a and b terminal.
Jun 2, 2010 at 11:24 PM
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OBXAUTOMEDIC
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Hello,

Ok, I am posting the proceedure and a diagram of the ALDL. Retry and see what happens.

Ground terminals A and B with the ignition "ON" and engine not running. The system will enter the diagnostic mode. In this mode, the computer will display a 12, three consecutive times, by flashing the "CHECK ENGINE", "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR LAMP" or light. A 12 consists of one flash, a short pause, then two flashes in rapid succession.

After 12 is displayed, any stored trouble s will be displayed by flashing the "CHECK ENGINE", "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR LAMP" light. All s are displayed 3 times each then a 12 will repeat. In the diagnostic mode, the computer will also energize all computer controlled relays and solenoids.

A possibility of the High Idle Problem could be a Vacuum Leak.
Jun 3, 2010 at 7:52 AM