2010 Cadillac Truck SRX AWD V6-3.0L Page 1614

2010 Cadillac Truck SRX AWD V6-3.0L Page 1614

瀚慖f the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

瀚慖f the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal 87 for a short to ground.

4. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.

瀚慖f the test lamp illuminates, test the control circuit for a short to voltage.

5. Parking brake applied and the transmission is in NEUTRAL or PARK. Momentarily install a 30 A fused jumper wire between the B+ circuit

terminal 30 and the control circuit terminal 87. Verify the starter is activated.

瀚慖f the starter does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the starter.

6. Ignition OFF, connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 85.

7. Transmission in park or neutral, cycle the ignition between the OFF and CRANK position. The test lamp should turn ON and OFF when

changing between the selected states.

瀚慖f the test lamp is always ON, test the control circuit for short to voltage. If the circuit tests normal, replace the K20 ECM.

瀚慖f the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace

the K20 ECM.

8. If all circuits tests normal, replace the KR27 starter relay.

Component Testing

Relay Test

1. Ignition OFF, disconnect the starter relay.

2. Test for 60-180 Ohms between terminals 85 and 86.

瀚慖f not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

* 30 and 86

* 30 and 87

* 30 and 85

* 85 and 87

瀚慖f not the specified value, replace the relay.

4. Install a 20 A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground. Test for

less than 2 Ohms between terminals 30 and 87.

瀚慖f greater than specified range, replace the 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

P0621

DTC P0621

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.