SERV. MAN UPDATE-SECTION 9J-A DIAG. OF INTERMIT. SIR CODE 24

SUBJECT: DIAGNOSIS OF INTERMITTENT SIR DIAGNOSTIC TROUBLE CODE (DTC) 24

MODEL/YEARS: 1990-92 TORONADO, 1991-92 CUSTOM CRUISER, 1991-93 NINETY EIGHT, 1992-93 EIGHTY EIGHT, 1993 CUTLASS CIERA

This bulletin updates service manual Section 9J-A "Chart A Tech 1 (Scan Tool) History Code Diagnosis". Please add this bulletin to the "Chart A Tech 1 (Scan Tool) History Code Diagnosis" in Section 9J-A.

When diagnosing an intermittent DTC 24 ("24 H", indicating History 24), when it is set alone or in combination with any other DTC(s), follow the diagnostic chart of "Current Code 24." However, when diagnosing an intermittent DTC 24, the DERM should NOT be replaced. It is extremely rare for an intermittent problem (History DTC) to be caused by the DERM itself.

DTC 24 can be set by any of the following conditions:

1. A short to ground or B+ on:

o Either SIR Coil Assembly circuit

o CKT 347

o CKT 348

o CKT 349

o CKT 688

o CKT 714

o CKT 752

2. A short to ground on CKT 753

3. An open in CKT 752

4. Improper resistance in the:

o Resistor Module

o Arming Sensor

o Discriminating Sensor(s)

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.