Erratic Speedometer/2nd Gear Shifting, VSS/ABS DTCs
Group Ref.: 8 - Chassis/Body ElectricalBulletin No.: 468301
Date: June, 1994
SUBJECT:
VEHICLE SPEED SENSOR CODES AND ERRATIC SPEEDOMETER
(REPLACE WIRE AND INSULATE)
MODELS:
1993 CHEVROLET AND GMC TRUCK MIL VANS WITH 4.3 ENGINE (VIN Z - RPO LB4), 4L60E TRANSMISSION (M30) BUILT PRIOR TO THE FOLLOWING VIN BREAKPOINTS:
DIVISION VIN
CHEVROLET 181368
GMC 531973
CONDITION:
Some owners may experience inoperative or erratic speedometer (Code 24 or 72), the vehicle shifting down into second gear (Code 24) or will not shift out of second gear (Code 72), and/or the Anti-Lock/ABS light illuminates on the instrument panel (Code 37).
CAUSE:
The Vehicle Speed Sensor wiring is damaged in the engine compartment between the valve cover and the pass through body connector. The protective cover at this portion of the engine harness and electrical control module harness is rubbing through, thus allowing the wiring harness to contact the valve cover and/or the thermac heat tube.
CORRECTION:
Replace wire according to guidelines found in the wire repair section of the Service Manual. Cut conduit to needed length. Added conduit must be taped at both ends to properly secure in place. Nylon conduit material, .87 - 1.0 inch (22 mm - 25.4 mm) diameter, can be procured locally if below listed part number is not readily available.
SERVICE PARTS INFORMATION:
P/N Description QTY
12013948 Conduit 1
Parts are currently available from GMSPO.
WARRANTY INFORMATION:
For vehicles repaired under warranty, use:
Labor Description Labor Time
Operation
N6270 Wiring and/or Use Published
connector repair, Labor Operation
Engine Time