Allison HD 4560P - DO NOT SHIFT LIGHT WILL NOT GO OUT AT START-UP; DO NOT SHIFT LIGHT FLASHES INTERMITTENTLY; NO DO NOT SHIFT LIGHT AT IGNITION

Copyright © 1998 General Motors Corp. 8–3
GENERAL TROUBLESHOOTING OF PERFORMANCE COMPLAINTS
WTEC II ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL
DO NOT SHIFT LIGHT WILL
NOT GO OUT AT START-UP
A. Vehicle Drives Normally
Faulty DO NOT SHIFT light,
relay, or circuit.
Replace relay or repair circuit
An LED rather than a lamp is
installed for the DO NOT
SHIFT light and the LED is
partially lighted from leakage
current
Install a lamp rather than an LED
for the DO NOT SHIFT light
B. Vehicle Does Not Drive
Faulty ECU Replace the ECU
Engine does not start Repair engine starting system
Faulty harness Repair harness (See Section 4
and Appendix E)
Faulty interface wiring to vehicle
electrical system
Repair wiring (See Appendix E)
Fluid temperature too low Warm transmission fluid
Faulty fluid temperature sensor/
circuit
Repair sensor or circuits
Faulty ECU Replace the ECU
DO NOT SHIFT LIGHT
FLASHES INTERMITTENTLY
Intermittent power to ECU Check input power to the ECU
and correct if necessary
Loose wiring to DO NOT
SHIFT light
Repair wiring
Faulty or incorrect ground wire
attachment
Repair ground circuit
Intermittent opening in
Circuit 115
Repair Circuit 115
NO DO NOT SHIFT LIGHT AT
IGNITION
Faulty light bulb or socket Replace light bulb or socket
Incorrect wiring to and from DO
NOT SHIFT light bulb
Repair wiring (See Appendix E)
Faulty wiring harness Check wiring between ECU and
DO NOT SHIFT light, and
repair where necessary
(See Appendix E)
Circuit 115 open Repair Circuit 115
Faulty ECU Replace ECU
Table 8–1. Troubleshooting Performance Complaints (cont’d)
Problem
Probable Cause Suggested Remedy