Retained Accessory Power Malfunction. Buick Lucerne 2007

For 1990-2009 cars only

Makes 🢒 Buick 🢒 2007 🢒 Lucerne 🢒 Power and Signal Distribution 🢒 Wiring Systems and Power Management 🢒 Retained Accessory Power Malfunction

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
RAP Relay Coil Supply Voltage	B1475, 1	1	2	--
Battery Positive Voltage (Relay Output)	3	4	2	--
Accessory Voltage (Relay Output)	3	4	2	--
Accessory Voltage (Relay Output)	3	4	2	--
Ground (RAP Relay)	--	1	--	--
All relay controlled RAP functions inoperative. Relay RAP remains on past the timer limit after key out and will not turn off when a vehicle door is opened. Partial relay controlled RAP functions inoperative with open fuse. Partial relay controlled RAP functions inoperative with fuse OK.

The retained accessory power (RAP) relay is located in the rear fuse block. The relay control is from the BCM. The relay switched output feeds the F 41 RAP, F 40 SHFTR SOL, and the F 17 S/ROOF fuses within the rear fuse block. Refer to Retained Accessory Power (RAP) Description and Operation for more detail on subsystems using RAP.

Diagnostic Aids

•	The radio and window RAP function are separate RAP functions controlled by serial data and the specific module. These functions are not effected by the BCM RAP relay circuits.

•	A short to ground or open/high resistance in the RAP 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 relay control or switched voltage circuits would cause the RAP function 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

•	Power Distribution Schematics

•	Door Control Module Schematics

Connector End View Reference

•	Master Electrical Component List

•	Vehicle Access Connector End Views

Description and Operation

Retained Accessory Power (RAP) Description and Operation

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

•	Scan Tool Data List

•	Scan Tool Data Definitions

Circuit/System Verification

Ignition ON, observe the scan tool parameters in the modules listed below while opening and closing each vehicle door. The reading should change appropriately between Door Closed/Door Ajar for the rear door ajar switches, and between Active/Inactive for the front door ajar switches.

Module/Parameter

•	BCM - Left Rear Door Ajar Sw.

•	BCM - Right Rear Door Ajar Sw.

•	Driver door module (DDM) - Driver Door Ajar Sw.

•	Passenger door module (PDM) - Passenger Door Ajar Sw.

⇒	If any parameter does not change as specified, refer to Door Ajar Indicator Malfunction for a door ajar indicator malfunction.

Command the scan tool Accy/RAP Relay OFF. Attempt to operate any RAP relay controlled component within 5 seconds. The component should not operate.

⇒	If the component does operate, refer to Circuit/System Testing.

Command the scan tool Accy/RAP Relay ON. Attempt to operate any RAP relay controlled component within 5 seconds. The component should operate.

⇒	If the component does not operate, refer to Circuit/System Testing.

Ignition ON, all doors closed. Observe the scan tool parameter Accy/RAP 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 BCM.

If all the above tests were normal and the radio is the only RAP concern, replace the radio.

Circuit/System Testing

Ignition OFF, disconnect the RAP Relay.
Test for less than 2 ohms of resistance between ground circuit terminal 108 and ground.

⇒	If greater than 2.0 ohms, test the ground circuit for an open/high resistance.

Connect a test lamp between control circuit terminal 107 and ground.
With the driver and passenger doors open, cycle the ignition key ON and OFF several times. The test lamp should turn ON and OFF when cycling the ignition switch.

⇒	If the test lamp remains ON all the time, test for a short to voltage on the relay coil control circuit. If the circuit tests normal, replace the BCM.

⇒	If the test lamp remains OFF all the time, test for a short to ground or open/high resistance on the relay coil control circuit. If the circuit tests normal, replace the BCM.

Connect a test lamp between the relay output voltage circuit terminal 109 and ground. The test lamp should not illuminate.

⇒	If the test lamp illuminates, test for a short to voltage on the following relay output circuits:

•	Battery positive voltage

•	Accessory voltage

If all circuits test normal, test or replace the RAP relay.

Component Testing

Relay Test

Ignition OFF, disconnect the RAP relay.
Test for 70-110 ohms of resistance between terminals 85 and 86.

⇒	If the resistance is not within the specified range, replace the relay.

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 relay.

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 2.0 ohms of resistance between terminals 30 and 87.

⇒	If greater than the specified range, replace the relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

•	Relay Replacement

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