COLD STARTABILITY IGNITION DIAGNOSIS

Model and Year 1983-84 CAVALIER WITH 2.0L ENGINE (VIN CODE P), AUTOMATIC TRANSMISSION AND FEDERAL EMISSIONS SYSTEMS

TO: ALL CHEVROLET DEALERS

This cancels and replaces Chevrolet Dealer Service Bulletin 84-253 dated May, 1985. The reissue clarifies the procedure to be used when diagnosing Cavaliers for cold startability.

On vehicles repaired per cold startability (reference Chevrolet Dealer Service Bulletin 84-221), normal check engine light procedures for trouble code 42 will no longer apply. This trouble code can no longer be set on these vehicles. On vehicles exhibiting the listed driveability conditions perform the following: DIAGNOSTIC SUPPLEMENT --------------------- 83-84 Vehicles With Cold Startability CONDITION: ---------

Engine Cranks but will not run or engine starts but Disconnect "set timing" connector. If immediately stops: engine starts see code chart 42 for open or short to ground in est ckt 423

Hard start-10 DEG F(-23 DEG C) may hear metallic Check: "knock" during crank. - Open Circuit 906 - Open Relay Ground - Faulty Relay (will not close during crank.)

Spark knock heavy loads. Loss of performance and Check and note timing. Disconnect "Set fuel economy. Timing" Connector and again note timing. No Change Check: - Open or Short to Ground in Bypass CKT 424. See Code 42. - Relay Contacts Stuck Closed

If the above procedures do not repair the condition, then the cold start repairs are not the cause and normal diagnostic procedures should be used.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.