(01/02)
KM816010
Page 21 of 44
MAINTENANCE MANUAL
Kenworth SmartWheel Troubleshooting Guide
16
C. Engine Retarder Does Not Work
C3. Symptom: Retarder works only when button held down or does not turn on.
C3-1. Possible cause: No ignition power to electronics module.
C3-2. Possible cause: Bad electronics module or steering wheel hub.
Check
Result
What To Do Next
C3-1A
Turn on ignition. Push any one of the
engine brake switches.
Check if LED over that switch is on.
LED on.
Go to
C3-2
.
LED lights only when button held
down.
Go to
C3-1B
.
LED does not turn on.
Go to
C3-2
.
C3-1B
Unplug 6-way connector from elec-
tronics module. Check voltage
between connector pins 4 and 3 with
ignition on.
Voltmeter reads battery voltage.
Go to C3-2.
No voltage.
Go to
C3-1C
.
C3-1 C
Check circuit breaker or fuse in
power distribution box position
Spare 33.
Circuit breaker/fuse OK.
There is an open circuit from the
power distribution box to electronics
module. Trace ckt PCB 33.
Circuit breaker bad/fuse blown.
Replace circuit breaker or fuse.
Determine cause for fuse to blow.
Check
Result
What To Do Next
C3-2A
Check for continuity between pins 13
and 14 of the 14 way connector on
the electronics module (with any
retarder setting turned on).
Continuity.
Problem must be in retarder wiring
or engine ECM. Retrace retarder cir-
cuits.
No continuity.
Problem may be in electronics mod-
ule or steering wheel hub. Go to A3.
