DaimlerChrysler Jeep Grand Cherokee 2002, Service Manual

Page: 200 / 284

Symptom:
P1605-IGNITION SWITCH PLAUSIBILITY
When Monitored and Set Condition:
P1605-IGNITION SWITCH PLAUSIBILITY
When Monitored: When the ignition is first turned on.
Set Condition: The ECM detects the Ignition Switch Sense momentarily return to the
OFF state during ECM initialization.
POSSIBLE CAUSES
INTERMITTENT CONDITION
ENGINE CONTROL MODULE
FUSED IGNITION SWITCH OUTPUT (RUN/START) CIRCUIT OPEN
FUSED IGNITION SWITCH OUTPUT (RUN/START) CIRCUIT SHORTED TO GROUND
TEST ACTION APPLICABILITY
1 NOTE: This DTC is set when the ECM sees a change from On to Off and then
back On within a few milliseconds during ECM initialization at Key On.
Look for an intermittent open or short to ground on the Ignition Switch
Sense circuit.
Turn the ignition on.
With the DRB, erase ECM DTCs.
Cycle the ignition switch on and off several times, pausing for at least 10 seconds at
each key off and key on.
Turn the ignition on.
With the DRB, read ECM DTCs.
Did this DTC set again? All
Yes
→
Go To 2
No
→
Go To 5
2 Turn the ignition off.
Disconnect the ECM harness connectors.
Disconnect the ignition switch harness connector.
Measure the resistance of the Fused Ignition Switch Output (RUN/START) circuit.
Is the resistance below 5.0 ohms? All
Yes
→
Go To 3
No
→
Repair the Fused Ignition Switch Output (RUN/START) circuit
for an open.
Perform ROAD TEST VERIFICATION - VER-2.
192
DRIVEABILITY - DIESEL
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