Troubleshooting

RENR2696-01 97
Troubleshooting Section
g00954711
Illustrat
ion 23
C. Refer to Troubleshooting, “Engine Wiring
Informat
ion” for wiring instructions.
D. Disconnect J1/P1 ECM engine harness connector
.
E. Connect the J1 bypass harness to the ECM
connect
or.
F. Remove the fuse F1 from the bypass harness and
from the
battery circuit.
G. Connect the unswitched battery cables directly
to the ba
ttery terminals.
H. Install the F1 fuse to the in-line fuse holder.
Note: The bypass harness directly connects the
keyswitch circuit to the ECM. The ECM will have
power un
til the connection to the + battery cable is
disconnected. Remove the “F1” fuse from the in-line
fuse holder in order to isolate the ECM.
I. Turn the keyswitch to the ON position while the
engine is off.
J. Access the active diagnostic code screen on
the electronic service tool. Check for one of the
follow
ing active diagnostic codes:
•
262-03 5 Volt Sensor Supply voltage more than
normal
•
262-04 5 Volt Sensor Supply voltage less than
normal
Note: When ECM engine harness connector J1/P1 is
disconne
cted and the keyswitch is in the ON position,
open circuit diagnostic codes will be “Active” or
“Logged” for all of the engine sensors. This is normal.
Expected Result:
The +5 V d
iagnostic code is active when the ECM
engine harness connector is disconnected.
Results
:
•
Yes – The +5 V diagnostic code is active when the
ECM engi
ne harness connector is disconnected.
Repair: Temporarily connect a test ECM to
the engi
ne J20/P20. The test ECM should be
programmed with the same values and with the
same parameters as the suspect ECM. Recheck
for a +5
V diagnostic code. If a +5 V diagnostic
code is not active, the original ECM is faulty.
Reconnect the original ECM and check the +5
Vdiagn
ostic codes. If a +5 V diagnostic code
becomes active, replace the ECM. If the ECM is
replaced, the new ECM should be programmed
with t
he same values and with the same parameter
as the suspect ECM.
STOP.