2010 Cadillac CTS Sedan AWD V6-3.6L Page 1600
* The following test must be performed on all three fan relay control circuit terminals.
3. 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 86
* KR20D cooling fan high speed relay terminal 86
* KR20E cooling fan speed control relay terminal 85
瀚慖f 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 ECM.
Note: The following tests must be performed on all three fan relay circuits.
4. 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.
瀚慖f the circuit voltage does not correspond to the specified values, test the control circuit for an open/high resistance or for a short to
voltage. If the circuit tests normal, replace the K20 ECM.
5. If all circuits test normal, test or replace the appropriate KR20 relay.
Component Testing
1. Ignition OFF, disconnect the KR20 cooling fan relay.
2. Test for 215-255 ohm between terminals 85 and 86.
瀚慖f not within the specified range, replace the KR20 cooling fan relay.
3. Measure the resistance between the terminals listed below. The DMM should display OL.
* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87
瀚慖f less than the specified range, replace the KR20 cooling fan relay.
4. Test for less than 2 ohm between terminals 30 and 87A.
瀚慖f greater than the specified range, replace the KR20E cooling fan relay.
5. 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 ohm between terminals 30 and 87.
瀚慖f 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.
* Relay Replacement (Attached to Wire Harness) (See: Power and Ground Distribution/Power Distribution Relay/Service and Repair/Relay
Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (See: Power and Ground Distribution/Power
Distribution Relay/Service and Repair/Relay Replacement (Within an Electrical Center))
* Control Module References (See: Testing and Inspection/Programming and Relearning)for ECM replacement, setup, and programming
Single Fan
DTC P0480, P0481, P0691, P0692, P0693, or P0694 (w/LLT)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
