IMPROPER CRANKSHAFT SENSOR REPLACEMENT DUE TO OIL

SUBJECT: IMPROPER CRANKSHAFT SENSOR REPLACEMENTS DUE TO OIL ON THE SENSOR (DIAGNOSIS)

VEHICLES AFFECTED: 1988-89 A/J/L/W WITH 2.8L, 3.1L AND 2.0L (ENG. CODES W,T,1)

APPLICATION: 1988-89 A, J, L, and W Cars with 2.8L (LB6), 3.1L (LHO), and 2.0L (LL8) Engines, with Direct Ignition System (DIS)

Condition:

---------- Crankshaft sensors returned from dealerships show a very high percentage of NTF (No Trouble Found) units.

Cause:

------ The sensors are usually replaced because of a driver comment of intermittent reduced performance, hesitation, or no start. When diagnosing the ignition system, the crankshaft sensor is found to be wet with oil, and is replaced. The oil, however, will not cause an operational problem with the ignition system, and the sensor should not be replaced for this reason.

The likely cause for the performance condition is an intermittent connection to the sensor. Replacing the sensor may fix the condition for a time, but the vehicle could return at a later time with the same condition.

Correction:

----------- 1. DO NOT replace the sensor because oil is found in the sensor. The sensor should only be replaced if diagnosis (such as CAMS or the Service Manual procedure) indicates that it is defective. The sensor may also be replaced if an oil leak is the original concern (this is very rare).

2. Check the wire harness connector to the sensor for proper contact. The wire terminals, or the connector body itself, may be replaced if necessary.

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.