SERVICE MANUAL UPDATE SEC. 9J SIR DIAGNOSIS 1992 ROADMASTER

SUBJECT: SERVICE MANUAL UPDATE - SECTION 9J - SIR DIAGNOSIS

MODELS AFFECTED: 1992 ROADMASTER

After start of production, changes were made in the SIR System involving the forward discriminating sensors and associated circuit wiring.

As a result, on vehicles before VIN NR421429, the 1992 Roadmaster Preliminary Service Manual must be used for SIR diagnosis.

For vehicles numbered NR421429 and later, the 1992 Roadmaster Final Service Manual must be used.

A quick check to verify early or later forward discriminating sensors and circuit wiring involves the number of pins on the right hand sensor:

Before VIN NR421429 - 3 pin sensor VIN NR421429 and later - 2 pin sensor

When servicing the SIR System on the 1992 Roadmaster, identify which SIR System circuit you are diagnosing and use the correct manual.

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.