For 1990-2009 cars

### 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
--- | --- | --- | --- | ---
Auxiliary Power Relay Switch B+ | 3 | 4 | 2 | --
Auxiliary Power Relay Control | B1445 02 | 1 | 1 | --
Auxiliary Power Relay Ignition | 3 | 4 | 2 | --
Auxiliary Power Relay Ground | -- | 1 | -- | --

1. All relay controlled retained power accessory functions inoperative.
2. Relay retained power accessory remains on past the timer limit after key out and will not turn off when a vehicle door is opened.
3. Partial relay controlled retained power accessory functions inoperative with open fuse.
4. Partial relay controlled retained power accessory functions inoperative with fuse OK.

### Circuit/System Description

The retained accessory power system allows specific vehicle functions to operate after the ignition is turned OFF for a predetermined time. Relay retained accessory power is controlled by the body control module (BCM) using inputs from the door ajar switches to determine control of the relay when the ignition is turned OFF. Radio retained accessory power is controlled by a serial data message from the BCM using inputs from the driver door open switch. Refer to Retained Accessory Power Description and Operation for more detail on subsystems using retained accessory power.

### Diagnostic Aids

The radio retained accessory power mode is a separate function and will still operate properly. The radio retained accessory power function is controlled by serial data and the specific module. These functions are not effected by the BCM retained accessory power relay circuits.

### Reference Information

#### Schematic Reference

• | Power Distribution Schematics

• | Power Moding Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Retained Accessory Power Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

Note: Battery voltage must remain above 9.6 V for retained accessory power to operate properly.

#### Radio retained accessory power

1. With all passenger doors closed, observe the courtesy lamps while opening and closing the driver door. The courtesy lamps should illuminate when the door is opened and turn off approximately 30 seconds after closing the door.

⇒ | If the courtesy lamp operation is incorrect from the drivers door, refer to Courtesy Lamps Malfunction.

2. If courtesy lamp operation is correct, and the radio is the only retained accessory power concern, replace the radio.

#### Relay retained accessory power

1. Ignition ON, observe the appropriate scan tool parameters listed below while opening and closing each vehicle door. The reading should change between Door Closed/Door Ajar.

• | Driver Door Ajar Switch

• | Left Rear Door Ajar Switch

• | Passenger Door Ajar Switch

• | Right Rear Door Ajar Switch

⇒ | If any parameter does not change as specified, refer to Door Ajar Indicator Malfunction.

2. Command the scan tool Accessory/Retained Accessory Power Relay Command OFF. Attempt to operate any retained accessory power relay controlled component within 5 seconds. The component should not operate.
3. Command the scan tool Accessory/Retained Accessory Power Relay Command ON. Attempt to operate any retained accessory power relay controlled component within 5 seconds. The component should operate.
4. Ignition ON, all doors closed. Observe the scan tool parameter Accessory/Retained Accessory Power Relay Command. Ignition OFF, key removed, the reading should be ON for approximately 10 minutes then change to OFF.

⇒ | If the parameter does not respond as specified, replace the K9 BCM.

### Circuit/System Testing

1. Ignition OFF, disconnect the KR70 auxiliary power relay.
2. Test for less than 2 Ω of resistance between the ground circuit terminal and ground.

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit terminal and ground.
4. With the driver and passenger doors open, cycle the ignition key ON and OFF. The test lamp should turn ON and OFF when cycling the S39 ignition switch.

⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.

⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the K9 BCM.

5. Connect a test lamp between the relay ignition circuit terminal and ground. The test lamp should not illuminate.

⇒ | If the test lamp illuminates, test the accessory voltage circuit for a short to voltage.

6. If all circuits test normal, test or replace the KR70 auxiliary power relay.

### Component Testing

#### Relay Test

1. Ignition OFF, disconnect the KR70 auxiliary power relay.
2. Test for 70-110 Ω of resistance between terminals 85 and 86.

⇒ | If the resistance is not within the specified range, replace the KR70 auxiliary power relay.

3. Test for infinite resistance between the following terminals:

• | 30 and 86

• | 30 and 87

• | 30 and 85

• | 85 and 87

⇒ | If not the specified value, replace the KR70 auxiliary power 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 2.0 Ω of resistance between terminals 30 and 87.

⇒ | If greater than the specified range, replace the KR70 auxiliary power relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• | Relay Replacement

• | Control Module References for module replacement, setup, and programming