2010 Cadillac Truck Escalade RWD V8-6.0L Hybrid Page 2558
lamp should turn ON for no longer than 10 seconds when the ignition is in the START position, and OFF in all other positions.
瀚慖f the test lamp is always on, test the control circuit for short to voltage. If the circuit tests normal, replace the 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
ECM.
4. If all circuits test normal, test or replace the STRTR relay.
Component Testing
Relay Test
1. Ignition OFF, disconnect the STRTR 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.
DTC Descriptor
DTC P0621
- Generator L-Terminal Circuit
Diagnostic Fault Information
Circuit/System Description
The engine control module (ECM) uses the charge indicator control circuit, or L-terminal circuit, to control the load of the generator on the engine.
