Speed Sensor - Erratic A/T/Speedometer Operation
90buick13Bulletin 91-6E-6
Date Nov. '90
Ref. No. 91-065-6E
Corp. Ref. No. 077142
SUBJECT: ERRATIC OR NO SPEEDOMETER AND ERRATIC TRANSAXLE OPERATION WITH POWERTRAIN CONTROL MODULE (PCM) CODE 24 (REPLACE VEHICLE SPEED SENSOR)
MODELS AFFECTED: 1991 PARK AVENUE, RIVIERA AND REATTA
BULLETIN COVERS:
A vehicle equipped with a Hydra-Matic 4T60-E transaxle may exhibit an erratic or no speedometer reading and erratic transaxle operation. These conditions could be accompanied by a Powertrain Control Module (PCM) Code 24. These conditions could be caused by an inoperative speed sensor. When the PCM detects an inoperative speed sensor, the PCM will force the transaxle into fail-safe 3rd gear range. Fail-safe 3rd gear, operation may cause customer comments that the vehicle is sluggish or slips. Also, an intermittent speed sensor condition may result in normal operation when cold, and when the vehicle is brought up to operating temperature, erratic operation of the speedometer and transaxle.
SERVICE PROCEDURE:
Replace the transaxle speed sensor with the part listed under "SERVICE PARTS INFORMATION ".
SERVICE PARTS INFORMATION:
Part Number Description Model Usage
10456034 Speed Sensor Assembly All
Parts are currently available from GMSPO.
SERVICE MANUAL REFERENCE:
Refer to 1991 Service Marual On-Car section for proper disassembly and assembly procedures.