P0691

SYMPTOM
P0691 -COOLING FAN 1 RELAY CONTROL CIRCUIT LOW

WHEN MONITORED
Ignition on with the Cooling fan No.1 Relay actuated.

SET CONDITION
The FCM recognizes and open or short to ground in the Cooling Fan Relay No.1 Control circuit.

POSSIBLE CAUSES
- (C24) FUSED B+ CIRCUIT
- (N201) LOW SPEED FAN RELAY CONTROL CIRCUIT OPEN
- (N201) LOW SPEED FAN RELAY CONTROL CIRCUIT SHORTED TO GROUND
- LOW SPEED RADIATOR FAN RELAY
- FCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Scan Tool Testing and Procedures

DIAGNOSTIC TEST
1. LOW SPEED RADIATOR FAN RELAY OPERATION





Ignition on, engine not running.
With a scan tool, actuate the Low Speed Radiator Fan Relay.
Is the Cooling Fan Relay operating?
Yes>> Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5. Powertrain Verification Test - Ver 5
No>> Go To 2

2. (A16) FUSED B+ CIRCUITS





Turn the ignition off.
Remove the Low Speed Radiator Fan Relay.
Using a 12-volt test light connected to ground, probe the (A16) Fused B+ circuits.
Is the voltage above 11.0 volts?
Yes>> Go To 3
No>> Repair the open or short to ground in the (A16) Fused B+ circuits. Inspect the related fuse and repair as necessary. Perform BODY VERIFICATION TEST-VER 1.

3. LOW SPEED RADIATOR FAN RELAY RESISTANCE
Measure the resistance of the Low Speed Radiator Fan Relay Coil.
Is the resistance between 60 to 80 ohms?
Yes>> Go To 4
No>> Replace the Low Speed Radiator Fan Relay. Perform BODY VERIFICATION TEST-VER 1.

4. (N201) COOLING FAN NO.1 CONTROL CIRCUIT OPEN





Disconnect the C3 FCM harness connector.
Measure the resistance of the (N201) Cooling Fan No.1 Relay Control circuit from the Relay to the C3 FCM harness connector.
Is the resistance below 5.0 ohms?
Yes>> Go To 5
No>> Repair the open in the (N201) Cooing Fan No.1 Relay Control circuit. Perform BODY VERIFICATION TEST-VER 1.

5. (N201) COOLING FAN NO.1 CONTROL CIRCUIT SHORTED TO GROUND





Measure the resistance between ground and the (N201) Cooling Fan No.1 Relay Control circuit at the Relay connection.
Is the resistance below 100 ohms?
Yes>> Repair the short to ground in the (N201) Cooling Fan No.1 Relay Control circuit. Perform BODY VERIFICATION TEST-VER 1.
No>> Go To 6

6. FRONT CONTROL MODULE

Note: Before continuing, check the FCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Were there any problems found?
Yes>> Repair as necessary. Perform BODY VERIFICATION TEST-VER 1.
No>> Replace Front Control Module per Service Information. Perform BODY VERIFICATION TEST-VER 1.