SERVICE MANUAL UPDATE - SEC. 5E1 - ABS DIAGNOSIS UPDATE

Subject: ANTILOCK BRAKE SYSTEM (ABS) DIAGNOSIS UPDATE

Model and Year: 1993 GEO PRIZM

The information contained in this bulletin replaces diagnostic information in ANTILOCK BRAKE SYSTEM (ABS) (SECTION 5E1) of the 1993 Geo Prizm Service Manual (ST373-93).

NO GEAR MOVEMENT

If all three motors released at this point and the motorpack appears to function properly, remove the hydraulic modulator/motor pack assembly and separate the motor pack from the hydraulic modulator; refer to "Motor Pack" under "unit Repair" in SECTION 5E1. Rotate each gear by hand on the hydraulic modulator. The front gears should be able to be rotated approximately five (5) turns lock-to-lock. If the gear does not turn freely or at least five (5) turns are not possible, replace the hydraulic modulator; refer to "Hydraulic Modulator" under "On-Vehicle Service" in SECTION 5E1.

The rear gear should rotate approximately four (4) turns. If the gear does not turn freely or at least four (4) turns are not possible, replace the hydraulic modulator; refer to "Hydraulic Modulator" under "On-Vehicle Service" in SECTION 5E1.

DIAGNOSTIC TROUBLE CODES (DTCS)

When diagnosing ABS DTCs A044, A045 and A046, use the attached charts in place of the diagnostic charts on pages 5E1 -105, 5E1 -107 and 5E1 -109.

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.