Circuit/System Testing

WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.

Voltage Out Of Range At All Times

WARNING: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.
The High Voltage Disabling procedure will perform the following tasks:

Identify how to disable high voltage.
Identify how to test for the presence of high voltage.
Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.

Failure to follow the procedures exactly as written may result in serious injury or death.

Ignition OFF, disconnect the 42V harness connector X2 at the APM.
Ignition OFF and scan tool disconnected, open and close the driver door, and wait 1 minute. Test for less than 3 ohms between the ground circuit terminal 1 X2 of the APM and ground.
- If greater than the specified range, test the APM ground circuits for an open/high resistance. If the circuits test normal, replace the APM.
Ignition OFF, connect a DMM between the 42V+ circuit terminal 2 X2 of the APM and ground.
Ignition ON, command the APM Intermediate Voltage Control ON with a scan tool. Test for 37.5-60 volts between the 42V+ circuit terminal 2 X2 terminal and ground. Command the APM Intermediate Voltage Control OFF after completing this test.
- If not within the specified range, replace the APM.
Ignition OFF, verify that the 42V harness connector X2 is connected under the PSCM.
- If the connector is not connected, connect the connector.
If all circuits test normal, replace the PSCM.

Low Voltage When Turning

Inspect the steering system for mechanical binding. The steering should have a heavy feel, if the power steering is disabled, but should not bind.
- If there is any mechanical binding in the steering system, refer to Steering Effort Hard in One or Both Directions (Standard) or Steering Effort Hard in One or Both Directions (Two-Mode) .
If all circuits test normal, replace the power steering motor.