P0691

[Alexzl1]

Anyone had trouble with cel p0691 ? The code apear when i start the car . I erase it with the aeroforce and it don't come back . ( until i re start the car ) . Relay , ground , everything seem ok . Fan motor ???

[DrkPhx]

Did you check the fan harness connection located on the passenger side by the upper radiator to see if there is a solid connection? If so, could be as simple as the fan relay as noted above. A digital mutli meter helps when chasing electrical gremlins.

[Alexzl1]

Originally Posted by DrkPhx

Did you check the fan harness connection located on the passenger side by the upper radiator to see if there is a solid connection? If so, could be as simple as the fan relay as noted above. A digital mutli meter helps when chasing electrical gremlins.

I've checked the relay , thanks

[DrkPhx]

Does the low speed fan actually come on? You can command the fans on with a decent scan tool to confirm.

[Alexzl1]

Originally Posted by DrkPhx

Does the low speed fan actually come on? You can command the fans on with a decent scan tool to confirm.

Yes , both speed works .

[Alexzl1]

I have checked and the fan motor are the same on an SS . My friend car is in storage to . I think i will make the switch to make the test .

[DrkPhx]

Good call. I can post the full DTC diagnostic if that helps.

[Alexzl1]

It would be appreciated . Thanks

[DrkPhx]

DTC P0480, P0481, P0691, P0692, P0693, or P0694 (with V6)

Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0480

• Cooling Fan Relay 1 Control Circuit

DTC P0481

• Cooling Fan Relays 2 and 3 Control Circuit

DTC P0691

• Cooling Fan Relay 1 Control Circuit Low Voltage

DTC P0692

• Cooling Fan Relay 1 Control Circuit High Voltage

DTC P0693

• Cooling Fan Relays 2 and 3 Control Circuit Low Voltage

DTC P0694

• Cooling Fan Relays 2 and 3 Control Circuit High Voltage

Diagnostic Fault Information






Circuit/System Description

The engine cooling fan system consists of a cooling fan assembly containing two electric cooling fans. The engine control module (ECM) uses two fan control circuits and a series of three relays to command the fans ON in either high speed or low speed, depending on cooling requirements. In low speed, both fans are turned ON at a reduced speed. High speed has both fans turned ON at full speed.

Conditions for Running the DTC

• The ignition voltage is greater than 11 volts.
• The ECM driver transitions from ON to OFF or from OFF to ON.
• DTC P0480, P0481, P0691, P0692, P0693, and P0694 run continuously when the conditions above are met.

Conditions for Setting the DTC

The commanded state of the ECM driver and the actual state of the control circuit do not match for greater than 5 seconds.

Action Taken When the DTC Sets

DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.

Diagnostic Aids

• The ECM has the capability of providing command to the fan relays even when a scan tool output control is being used. Always refer to the fan control command parameters on the scan tool to know which fans are being commanded ON by the ECM.
• The scan tool cooling fan output control operates as follows:
• Cooling Fan Relay 1 operates both fans at a low speed
• Cooling Fan Relay 2 and 3 operates the left fan at a high speed
• Cooling Fan Relay 1, 2 and 3 operates both fans at a high speed
• When disconnecting or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the correct orientation in the fuse block. Test the mating electrical terminals for tightness.

Reference Information

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

• Component Connector End Views
• Electrical Center Identification Views

Description and Operation

Cooling Fan Description and Operation


DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Engine operating, command the cooling fans ON and OFF in each of the commanded states. An audible click should be heard when changing between each of the commanded states.
2. Observe the DTC information with a scan tool. DTC P0480, P0481, P0691, P0692, P0693, or P0694 should not set.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

1. Ignition OFF, disconnect all of the KR20 Cooling Fan Relays.

Note: The following tests must be performed on all three fan relay circuits.

1. Ignition ON, verify that a test lamp illuminates between ground and the relay coil ignition circuit terminal listed below:

• • KR20C Cooling Fan Low Speed Relay terminal 86
  • KR20D Cooling Fan High Speed Relay terminal 85
  • KR20E Cooling Fan Speed Control Relay terminal 85

¤ If the test lamp does not illuminate, test the relay coil ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay coil ignition circuit fuse is open, test all components connected to the ignition circuit and replace as necessary.
Note: The following tests must be performed on all three fan relay circuits.

1. Connect the red lead of the DMM to a control circuit terminal listed below. Connect the black lead to ground. Set the DMM on the diode setting. The DMM should display OL.

• • KR20C Cooling Fan Low Speed Relay terminal 85
  • KR20D Cooling Fan High Speed Relay terminal 86
  • KR20E Cooling Fan Speed Control Relay terminal 86

¤ If less than the specified range, test the appropriate relay coil control circuit for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module.
Note: The following tests must be performed on all three fan relay circuits.

1. Command the cooling fan relay ON and OFF with a scan tool. The DMM should transition from OL when commanded OFF to less than 1 V when commanded ON.

¤ If the circuit voltage does not correspond to the specified values, test the control circuit for an open/high resistance or a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.

1. If all circuits test normal, test or replace the appropriate KR20 Cooling Fan Relay.

Component Testing

1. Ignition OFF, disconnect the KR20 Cooling Fan Relay.
2. Test for 70-110 ohms between terminals 85 and 86.

¤ If not within the specified range, replace the KR20 cooling fan relay.

1. Test for infinite resistance between the terminals listed below.

• • 30 and 86
  • 30 and 87
  • 30 and 85
  • 85 and 87

¤ If less than the specified range, replace the KR20 Cooling Fan Relay.

1. Test the KR20E Cooling Fan Speed Control Relay for less than 2 ohms between terminals 30 and 87A.

¤ If greater than the specified range, replace the KR20E Cooling Fan Speed Control Relay.

1. Connect a 20 A fused jumper wire between relay terminal 85 and B+. Connect a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87.

¤ If greater than the specified range, replace the KR20 Cooling Fan Relay.
Repair Instructions

Perform the Diagnostic Repair Verification See: Verification Tests after completing the diagnostic procedure.

[DrkPhx]

Cooling Fan Description and Operation






The engine cooling fan system consists of 2 electric cooling fans and 3 fan relays. The relays are arranged in a series/parallel (S/P) configuration that allows the engine control module (ECM) to operate both fans together at low or high speeds. The cooling fans receive positive voltage from the cooling fan relays which receive battery positive voltage from the underhood fuse block.

In low speed operation, the ECM applies ground to the coil side of the cooling fan low speed relay. This energizes the coil and applies voltage directly to the right cooling fan through the switch side of the low speed relay. The right cooling fan is connected in series to the left cooling fan through the de-energized series/parallel (S/P) cooling fan speed control relay. The series circuit operates both fans at low speed.

In high speed operation, the ECM applies a ground to the coil side of the cooling fan low speed relay, the S/P cooling fan speed control relay, and the cooling fan high speed relay. When energized, the high speed fan relay applies voltage directly to the left cooling fan through the switch side of the relay. Simultaneously, the low speed fan relay and the S/P speed control relay provide ignition voltage and a direct path to ground for the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.

[DrkPhx]

Engine Cooling Schematics

Cooling Fans

[DrkPhx]

I copied and pasted so the links won't actually work.

[Alexzl1]

Thank you .

[Alexzl1]

I have checked and at high speed only 1 fan work and no voltage on the other fan connector