P0691

P0691-COOLING FAN 1 CONTROL CIRCUIT LOW

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Powertrain Control Module (PCM) sends a Pulse-Width Modulated (PWM) signal to the Radiator Fan Module to control speed and a ground signal to the Radiator Fan Relay to control on/off operation.

- When Monitored:
With the ignition on.

Battery voltage greater than 10 volts.



- Set Condition:
The DTC is set if the Radiator Fan Relay PWM circuit is shorted to ground.





Diagnostic Test

1. ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, clear read DTCs.

Does the scan tool display this DTC as active?

Yes

- Go To 2

No

- Test complete, the condition or conditions that originally set this DTC are not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.
- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. CHECK THE (K173) RADIATOR FAN PWM CONTROL CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition off.
2. Disconnect the Radiator Fan Module connector.
3. Disconnect the PCM C1 harness connector.
4. Measure the resistance of the (K173) Radiator Fan PWM Control circuit to battery ground at the Radiator Fan Module.

Is the resistance above 10k ohms?

Yes

- Go To 3

No

- Repair the short to ground in the (K173) Radiator Fan PWM Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

3. CHECK THE (K173) RADIATOR FAN PWM CONTROL CIRCUIT FOR A SHORT TO THE (Z903) RADIATOR FAN MODULE GROUND CIRCUIT
1. (With the Fan Module and PCM C1 connectors still disconnected) Measure the resistance between the (K173) Radiator Fan PWM Control circuit and the (Z903) Radiator Fan Module ground circuit at the Fan Module connector.

Is the resistance above 10k ohms?

Yes

- Go To 4

No

- Repair the short from the (K173) Radiator Fan PWM Control circuit to the (Z903) Radiator Fan PWM Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

4. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the relay and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Verify that there is good pin to terminal contact at the relay and PCM harness connectors.
5. Perform any Technical Service Bulletins (TSBs) that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module (PCM). .
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.