P1491

Test 1 - 2:

Tests 3 - 6:

Tests 7 - 10:

Tests 11 - 12:

SYMPTOM
P1491-RAD FAN CONTROL RELAY CIRCUIT

WHEN MONITORED
With the ignition ON. Battery voltage greater than 10 volts.

SET CONDITION
An open or shorted circuit is detected in the radiator fan relay control circuit.

POSSIBLE CAUSES
- Radiator fan relay intermittent operation
- Intermittent condition
- Ground circuit
- Fused B+ output circuit
- Powertrain control module
- Radiator fan relay control circuit short to ground
- Radiator fan relay control circuit open (IPM)
- Radiator fan relay control circuit open (PCM)
- Radiator fan relay control circuit shorted to ground (IPM)
- Radiator fan relay control circuit short to ground (PCM)
- Intelligent power module (open)
- Intelligent power module (shorted)