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. |
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Accessory Voltage (Relay Output) | 1 | 2 | 3 | -- |
1. Partial relay controlled RAP functions inoperative with open fuse. 2. Partial relay controlled RAP functions inoperative with fuse OK. 3. RAP remains on past the timer limit after key out and will not turn off when a vehicle door is opened. | ||||
Circuit/System Description
The body control module (BCM) controls the RAP/ACCY relay. The relay allows the BCM to control the application of power to the feed circuits of multiple subsystems and components. When the ignition switch is in either the ACC or the ON position, the BCM energizes the relay by providing ground to the RAP relay coil control circuit. The BCM also energizes the relay for a specific time after the ignition key is removed providing a set of specific conditions are met. The RAP/ACCY relay outputs are fused separately protecting each component/system from becoming inoperative when a short to ground is on a different fused component/system fuse. Refer to retained accessory power (RAP) description and operation for more information on RAP.
Diagnostic Aids
| • | The radio, vehicle communication interface module (VCIM) (OnStar®) and rear seat entertainment assembly RAP functions are separate RAP functions controlled by serial data and the specific module. These functions are not effected by the RAP/ACCY relay circuits. |
| • | A short to ground or open/high resistance in the RAP/ACCY relay switched voltage circuits will cause only part of the RAP functions to be inoperative. Diagnose these symptoms within the respective system sections. |
| • | A short to voltage on the RAP/ACCY relay control or switched voltage circuits would cause the relay controlled RAP functions to remain on past the designated time. |
| • | A stuck relay switch could cause a RAP always on, or a RAP inoperative condition. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Retained Accessory Power (RAP) Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Important: Battery voltage must remain above 9.6 V for RAP to operate properly.
Verify DTC B1477 or B1478 is not set in the BCM.
| ⇒ | If DTC B1477 or B1478 is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle . |
Circuit/System Testing
- Ignition OFF, disconnect the RAP/ACCY relay.
- Connect a test lamp between the relay accessory voltage circuit terminal 87 and ground.
| ⇒ | If the test lamp illuminates, refer to retained accessory power (RAP) description and operation and remove each fuse listed one at a time until the test lamp turns off. Test the accessory voltage circuit of the fuse that caused the test lamp to turn off for a short to voltage. |
| ⇒ | If the test lamp does not illuminate, test or replace the RAP/ACCY relay. |
Component Testing
Relay Test
- Ignition OFF, disconnect the RAP relay.
- Test for 70-110 ohms between terminals 85 and 86.
- Test for infinite resistance between the following terminals:
- Install a 20 amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 5.0 ohms between terminals 30 and 87.
| ⇒ | If the resistance is not within the specified range, replace the relay. |
| • | 30 and 86 |
| • | 30 and 87 |
| • | 30 and 85 |
| • | 85 and 87 |
| ⇒ | If not the specified value, replace the relay. |
| ⇒ | If greater than specified, replace the relay. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
