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P1643-VISCOUS HEATER RELAY OPEN CIRCUIT —
TEST
2
WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
NOTE: The conditions that set the DTC are not present at this time. The
following list may help in identifying the intermittent condition.
With the engine running at normal operating temperature, monitor the DRB
parameters related to the DTC while wiggling the wiring harness. Look for param-
eter values to change and/or a DTC to set.
Review the DTC When Monitored and Set Conditions. If possible, try to duplicate the
conditions under which the DTC was set.
Refer to any Technical Service Bulletins (TSB) that may apply.
Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or
partially broken wires.
Visually inspect the related wiring harness connectors. Look for broken, bent, pushed
out, or corroded terminals.
Were any of the above conditions present?
Yes → Repair as necessary.
→ Test Complete.
No
3
Turn the ignition off.
Disconnect the Viscous Heater Relay from the PDC.
Turn the ignition on.
Using a 12-volt test light connected to ground, check the ASD Relay Output circuit at
the Viscous Heater Relay connector in the PDC.
Does the test light illuminate brightly?
Yes → Go To 4
→ Repair the ASD Relay Output circuit for an open.
No
4
Turn the ignition off.
Install a substitute relay in place of the Viscous Heater Relay.
Turn the ignition on.
With the DRB, actuate the Viscous/Cabin Heater Relay for at least 20 seconds.
With the DRB, read ECM DTCs.
Did this DTC set again?
Yes → Go To 5
→ Replace the Viscous Heater Relay.
No
5
Turn the ignition off.
Disconnect the ECM harness connectors.
Remove the Viscous Heater Relay.
Remove the ASD Relay from the PDC.
Connect a jumper wire between cavity 30 and cavity 87 of the ASD Relay connector
in the PDC.
Turn the ignition on.
Measure the voltage on the Viscous Heater Relay Control circuit.
Is the voltage above 1.0 volt?
Yes → Repair the Viscous Heater Relay Control circuit for a short to
→ Go To 6
No
ACTION
Perform ROAD TEST VERIFICATION - VER-2.
Perform ROAD TEST VERIFICATION - VER-2.
Perform ROAD TEST VERIFICATION - VER-2.
voltage.
Perform ROAD TEST VERIFICATION - VER-2.
DRIVEABILITY - DIESEL
195
Continued
APPLICABILITY
All
All
All
All
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