204 KENR9126
Troubleshooting Section
Results:
•
OK – The harness connects the ECM to the glow
plug start aid relay and there are no shorts to other
circuits. The
ECM or the glow plug start aid relay is
suspect.ProceedtoTestStep4.
•
Not OK – The ha
rness is faulty.
Repair: If the resistance between P1:29 or P1:32
and each of t
he other pins on the P1 connector is
less than 10,000 Ohms then there is a short circuit
or high resistance in the connection to another
wire. Locat
e the open circuit, the short circuit, or
high resistance in the connection in the harness.
Repair the connectors or the harness and/or
replace th
e connectors or the harness. Ensure that
all of the seals are correctly in place and ensure
that the connectors are correctly coupled. Replace
any fuses t
hat may be open circuit.
Use the electronic service tool in order to clear all
logged di
agnostic codes and then verify that the
repair has eliminated the fault.
If the fau
lt still exists, proceed to Test Step 4.
Test Step 4. Bypass the ECM In Order to
Check the Operation of the Glow Plug
Start Aid Relay
A. Turn the keyswitch to the OFF position.
B. Disco
nnect the connection from test point “D” on
the glow plug start aid relay.
C. Conne
ct a jumper wire between the battery ground
and terminal “D” on the glow plug start aid relay.
D. Meas
ure the voltage from the battery ground and
terminal “B” on the glow plug start aid relay.
E. Conn
ect a multimeter between terminal “B” on the
glow plug start aid relay and the battery ground.
F. Tur
n the keyswitch to the ON position.
Note: The engine has not been started at this Test
Ste
p.
G. Use the electronic service tool in order to operate
th
e glow plugs.
H. Measure the voltage from the battery ground and
te
rminal “B” on the glow plug start aid relay.
Expected Result:
The keyswitch is in the OFF position. The voltage
should be 0 VDC.
The keyswitch is in the ON position. The measured
voltage for the
12 Volt systems is a constant 10.5
to 13.5 VDC. The measured voltage for the 24 Volt
systems is a constant 21.0 to 27.0 VDC.
Results:
•
OK – The glow p
lug start aid relay is operating
correctly. Reconnect the connection to test point
“D” on the glow plug start aid relay. Proceed to
Test Step 5.
•
Not OK – The glow plug start aid relay is faulty.
Repair: Replace the glow plug start aid relay.
Use the electronic service tool in order to clear all
logged dia
gnostic codes and then verify that the
repair eliminates the fault.
If the faul
t still exists, proceed to Test step 5.
Test Step 5. Check the ECM
A. Make sure that the latest flash file for the
application is installed in the ECM. Refer to
Troubles
hooting, “Flash Programming”.
B. Contact the Global Technical Support Center.
Note: This consultation can greatly reduce the repair
time.
C. If the Global Technical Support Center
recommends the use of a test ECM, install a test
ECM. Re
fer to Troubleshooting, “Replacing the
ECM”.
D. Use th
e electronic service tool in order to perform
a “Glow Plug Override Test”.
E. If the
fault is resolved with the test ECM, reconnect
the suspect ECM.
Expe
cted Result:
The replacement ECM functions correctly. Performing
the “
Glow Plug Override Test” energizes the glow
plugs. The fault returns with the suspect ECM.
Res
ults:
•
OK – The replacement ECM functions correctly.
Repair: Install the replacement ECM. Refer to
Troubleshooting, “Replacing the ECM”.
Use the electronic service tool in order to clear all
logged diagnostic codes and then verify that the
re
pair eliminates the fault.
STOP.
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