DELAYED UPSHIFT. Chevrolet Chevy MD Steel Tilt 67.9" 1995

SUBJECT: DELAYED UPSHIFT (ADJUST ACCELERATOR CABLE/TPS/KICKDOWN SWITCH)

MODELS: 1995-96 CHEVROLET TILTMASTER AND GMC FORWARD W4 MODELS WITH JATCO ELECTRONIC TRANSMISSION

CONDITION:

SOME OWNERS MAY COMMENT ABOUT A DELAYED UPSHIFT CONDITION IN WHICH THE TRANSMISSION WILL NOT MAKE AN UPSHIFT UNTIL THE ACCELERATOR PEDAL IS RELEASED.

CAUSE:

THE ACCELERATOR CABLE AND POSSIBLY THE THROTTLE POSITION SENSOR (TPS) AND KICKDOWN SWITCH REQUIRE ADJUSTMENT.

CORRECTION:

ADJUST THE ACCELERATOR CABLE FOLLOWING THE SERVICE PROCEDURE IN SECTION 6C1 OF THE APPROPRIATE SERVICE MANUAL AND INSPECT. IF REQUIRED, ADJUST THE THROTTLE POSITION SENSOR (TPS) PER THE SERVICE PROCEDURE.

SERVICE PROCEDURE:

CHECK TPS ADJUSTMENT AND OPERATION FOLLOWING THE PROCEDURE DESCRIBED IN SECTION 7A2 OF THE APPROPRIATE SERVICE MANUAL. USE THE PROCEDURE FOR DTC 21- THROTTLE POSITION SENSOR (WIRE BREAKING/SHORT CIRCUIT). IF TPS ADJUSTMENT IS REQUIRED, PERFORM APPROPRIATE ADJUSTMENT PROCEDURE BELOW:

ADJUSTMENT (WITH SCAN TOOL) THROTTLE POSITION SENSOR REMOVE TWO 8 MM NUTS HOLDING ACCELERATOR BRACKET TO SUPPORT. DISCONNECT ACCELERATOR CABLE FROM ACCELERATOR BRACKET. DISCONNECT CONNECTORS FROM KICKDOWN SWITCH AND ACCELERATOR SWITCH. LOWER ACCELERATOR BRACKET AND TURN IT SIDEWAYS TO EXPOSE TPS ADJUSTING BOLTS. HOOK UP SCAN TOOL. LOOSEN TPS ADJUSTING BOLTS. WHILE MONITORING SCAN TOOL, TURN TPS LEFT OR RIGHT TO OBTAIN VOLTAGE READING BETWEEN 3.8 AND 4.5 VOLTS. ONCE ADJUSTED, TIGHTEN ADJUSTING BOLTS. FOLLOW APPROPRIATE ABOVE STEPS IN REVERSE ORDER TO COMPLETE THIS ADJUSTMENT PROCEDURE.

ADJUSTMENT (WITHOUT SCAN TOOL)

THROTTLE POSITION SENSOR TURN STARTER SWITCH TO ON POSITION. REMOVE TWO 8 MM NUTS HOLDING ACCELERATOR BRACKET TO SUPPORT. DISCONNECT CONNECTORS FROM KICKDOWN SWITCH AND ACCELERATOR SWITCH. LOWER ACCELERATOR BRACKET AND TURN IT SIDEWAYS TO EXPOSE TPS ADJUSTING BOLTS. AT TCM, PERFORM FOLLOWING USING VOLTMETER: INSERT VOLTMETER PROBES INTO BACK OF CONNECTOR B47 AT TERMINALS B47-20 AND B47-16 (TERMINAL B47- 16 IS GROUND). LOOSEN TPS ADJUSTING BOLTS. WHILE MONITORING VOLTMETER, TURN TPS LEFT OR RIGHT TO OBTAIN VOLTAGE READING BETWEEN 3.8 AND 4.5 VOLTS. ONCE ADJUSTED, TIGHTEN ADJUSTING BOLTS. FOLLOW APPROPRIATE ABOVE STEPS IN REVERSE ORDER TO COMPLETE THIS ADJUSTMENT PROCEDURE.

INSPECTION:

KICKDOWN SWITCH CHECK KICKDOWN SWITCH OPERATION. IMPORTANT: IF PROPERLY ADJUSTED, THE KICKDOWN SWITCH SHOULD ACTIVATE AT 100% THROTTLE ONLY. IF THE KICKDOWN SWITCH REQUIRES ADJUSTMENT, PROCEED WITH THE FOLLOWING ADJUSTMENT STEPS:

ADJUSTMENT:

KICKDOWN SWITCH DISCONNECT KICKDOWN SWITCH CONNECTOR. LOOSEN 17 MM NUT SECURING KICKDOWN SWITCH TO BRACKET. PRESS ACCELERATOR PEDAL TO FLOOR, THEN SCREW IN KICKDOWN SWITCH UNTIL IT MAKES A TICKING SOUND INDICATING SWITCH IS ON. TIGHTEN 17 MM NUT. CONNECT KICKDOWN SWITCH CONNECTOR AND CHECK KICKDOWN SWITCH OPERATION.

IMPORTANT: AFTER ADJUSTING THE TPS AND/OR KICKDOWN SWITCH, PERFORM THE FOLLOWING PROCEDURE. THIS WILL FORCE THE ECM TO "RELEARN" THE TPS AND/OR KICKDOWN SWITCH ADJUSTMENTS MADE PREVIOUSLY. TURN STARTER SWITCH TO ON POSITION. DO NOT START ENGINE. SLOWLY PRESS ACCELERATOR PEDAL TO FLOOR, THEN RELEASE BACK TO IDLE POSITION. TURN STARTER SWITCH OFF. TURN STARTER SWITCH TO START POSITION. PRESS ACCELERATOR PEDAL TO FLOOR, THEN RELEASE BACK TO IDLE POSITION. TURN STARTER SWITCH OFF.

ONCE ALL NECESSARY ADJUSTMENTS IN THIS SERVICE PROCEDURE HAVE BEEN MADE, ROAD TEST THE VEHICLE TO VERIFY PROPER SHIFTING.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE: LABOR OP DESCRIPTION LABOR TIME J5327 ACCELERATOR CABLE, ADJUST 0.3 HR J5348 KICKDOWN SWITCH, ADJUST 0.4 HR K6510 TPS, ADJUST 0.3 HR

IMPORTANT: LABOR OPERATION IS CODED TO BASE VEHICLE COVERAGE IN THE WARRANTY SYSTEM.

FIGURES: 0 CAPTIONS: 0

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.