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 |
|---|---|---|---|---|
DDM B+ | U0199 00 | U0199 00 | -- | -- |
Door Lock Relay Switch B+ | 4 | 4 | -- | -- |
Door Unlock Relay Coil B+ | 3 | 3 | -- | -- |
Door Unlock Relay Switch B+ | 3 | 3 | -- | -- |
Door Unlatch (Limo) Relay Switch B+ | 5 | 5 | -- | -- |
Right Middle Door Park Relay Switch B+ | 5 | 5 | -- | -- |
Left Middle Door Park Relay Switch B+ | 5 | 5 | -- | -- |
FPDM B+ | U0200 00 | U0200 00 | -- | -- |
Driver Door Lock Actuator Lock Control | 1 | 1 | 1 | -- |
Driver Door Lock Actuator Unlock Control | 1 | 1 | 1 | -- |
Driver Door Key Switch Low Reference | -- | 1, 2, 3, 4 | 1,2,3,4 | -- |
Driver Door Key Switch Signal | 1, 2, 3, 4 | 1, 2, 3, 4 | 1, 2, 3, 4 | -- |
Park Enable Signal | B0005 00 | 5 | 5 | -- |
Passenger Door Lock Actuator Lock Control | B3135 00 | B3135 00 | B3135 00 | -- |
Passenger Door Lock Actuator Unlock Control | B3130 00 | B3130 00 | B3130 00 | -- |
Rear Door Latch Actuator Lock Control | 4 | 4 | 4 | -- |
Rear Door Latch Actuator Unlock Control | 3 | 3 | 3 | -- |
Middle Door Latch Actuator Lock Control | 4 | 4 | 4 | -- |
Middle Door Latch Actuator Unlock Control | 3 | 3 | 3 | -- |
Back Door Latch Actuator Lock Control | 4 | 4 | 4 | -- |
Back Door Latch Actuator Unlock Control | 3 | 3 | 3 | -- |
Right Middle Door Release Switch Control | 5 | 5 | 5 | -- |
Left Middle Door Release Switch Control | 5 | 5 | 5 | -- |
DDM Ground | -- | U0199 00 | U0199 00 | -- |
Door Unlock Relay Switch Ground | -- | 3 | 3 | -- |
Door Lock Relay Coil Ground | -- | 4 | 4 | -- |
Door Lock Relay Switch Ground | -- | 4 | 4 | -- |
Door Unlatch (Limo) Relay Coil Ground | -- | 5 | 5 | -- |
Left Middle Door Park Relay Ground | -- | 5 | 5 | -- |
Right Middle Door Park Relay Ground | -- | 5 | 5 | -- |
FPDM Ground | -- | U0200 00 | U0200 00 | -- |
1. Driver Door Latch Malfunction 2. Passenger Door Latch Malfunction 3. Rear, Middle, Back Door Unlock Inoperative 4. Rear, Middle, Back Door Lock Inoperative 5. Release Switch Malfunction | ||||
Circuit/System Description
The driver and front passenger power door lock switches are integral components of the driver door module (DDM) and front passenger door module (FPDM). The switches consist of 2 positions, lock and unlock, and are in the normally open state. When placed in either the lock or unlock positions, the switches provide a direct input to their respective door control module. When a power door lock switch is operated in the lock or unlock position, the associated door control module responds by sending a GMLAN serial data message indicating a change in the switch position. This serial data message is received by the opposite door control module as well as the body control module (BCM). The DDM and FPDM respond to the lock/unlock request by activating their respective power door lock motors to lock or unlock the front doors. The BCM is responsible for controlling the left and right rear passenger door lock motors. The BCM, upon receipt of a lock or unlock serial data signal, will control either the rear door lock or unlock relay. When the appropriate door lock relay is energized, the rear power door lock motors will lock or unlock the rear doors.
This vehicle may also be configured as a limousine or a hearse by various upfitters and as such may be equipped with middle doors or a rear door.
Reference Information
Schematic Reference
Door Lock/Indicator Schematics
Connector End View Reference
Description and Operation
Power Door Locks Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON, observe the scan tool Door Lock Actuator Cmd parameter while commanding the doors to LOCK and UNLOCK by using the appropriate front door lock switch. The parameter should change from Off to Lock and Unlock.
- Command all doors to LOCK and UNLOCK with a scan tool. All of the vehicle doors should LOCK and UNLOCK.
| ⇒ | If the parameter does not change, refer to DDM/FPDM Malfunction. |
| ⇒ | If a front door does not LOCK or UNLOCK, refer to DDM/FPDM Malfunction. |
| ⇒ | If either LR, RR, middle or rear doors do not UNLOCK, refer to Door Unlock Relay Malfunction. |
| ⇒ | If either LR, RR, middle or rear doors do not LOCK, refer to Door Lock Relay Malfunction. |
Circuit/System Testing
DDM/FPDM Malfunction
- Ignition OFF, disconnect the X1 harness connector at the appropriate door module.
- Test for less than 1.0 ohm between the ground circuit terminal 6 and ground.
- Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 4 and ground.
- Ignition OFF, connect the X1 harness connector at the door module and disconnect the X2 harness connector at the front door latch assembly.
- Connect a test lamp between control circuit terminal B and control circuit terminal A.
- Ignition ON, command the appropriate front door latch to LOCK and UNLOCK by using the front door lock switch. The test lamp should briefly illuminate when commanding the LOCK and UNLOCK states.
- If all circuits test normal, test or replace the door latch assembly.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or open/high resistance. If the circuit tests normal and the door module fuse is open, replace the appropriate door module. |
| ⇒ | If the test lamp remains OFF during either of the commands, test for a short to ground or an open/high resistance on either control circuit. If the circuits test normal, replace the door module. |
| ⇒ | If the test lamp remains ON during either of the commands, test for a short to voltage on either control circuit. If the circuits test normal, replace the door module. |
Door Unlock Relay Malfunction
- Ignition OFF, disconnect the UNLOCK relay.
- Test for less than 1.0 ohm between the relay switch side ground circuit terminal and ground.
- Ignition ON, verify that a test lamp does not illuminate between the relay switch side control circuit terminal and ground.
- Verify that a test lamp illuminates between the relay coil side B+ circuit terminal and ground.
- Verify that a test lamp illuminates between the relay switch side B+ circuit terminal and ground.
- Connect a test lamp between the relay coil control circuit terminal and the relay coil B+ circuit terminal.
- Command the rear doors to UNLOCK with a scan tool. The test lamp should briefly illuminate when commanding the UNLOCK state.
- Ignition OFF, connect the UNLOCK relay. Disconnect the X2 harness connector at the rear door latch assembly.
- Test for less than 1 ohm between the control circuit terminal A and ground.
- Connect a test lamp between control circuit terminal A and ground.
- Ignition ON, command the door latch to UNLOCK with a scan tool. The test lamp should briefly illuminate when commanding the UNLOCK state.
- If all circuits test normal, test or replace the door latch assembly.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. |
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. |
| ⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM. |
| ⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. |
| ⇒ | If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuits test normal, test or replace the UNLOCK relay. |
| ⇒ | If 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, test or replace the UNLOCK relay. |
Door Lock Relay Malfunction
- Ignition OFF, disconnect the LOCK relay.
- Test for less than 1.0 ohm between the relay switch side ground circuit terminal and ground.
- Ignition ON, verify that a test lamp does not illuminate between the relay switch side control circuit terminal and ground.
- Ignition OFF, test for less than 1.0 ohm between the relay coil side ground circuit terminal and ground.
- Verify that a test lamp illuminates between the relay switch side B+ circuit terminal and ground.
- Connect a test lamp between the relay coil control circuit terminal and the relay coil side ground circuit terminal.
- Command the rear doors to LOCK with a scan tool. The test lamp should briefly illuminate when commanding the LOCK state.
- Ignition OFF, connect the LOCK relay. Disconnect the X2 harness connector at the appropriate door latch.
- Test for less than 1 ohm between the control circuit terminal B and ground.
- Connect a test lamp between control circuit terminal B and ground.
- Ignition ON, command the rear doors to LOCK with a scan tool. The test lamp should briefly illuminate when commanding the LOCK state.
- If all circuits test normal, test or replace the door latch assembly.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. |
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. |
| ⇒ | If 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 BCM. |
| ⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. |
| ⇒ | If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuits test normal, test or replace the LOCK relay. |
| ⇒ | If 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, test or replace the LOCK relay. |
Component Testing
Door Latch Assembly Test
- Ignition OFF, disconnect the harness connector at the appropriate door latch assembly.
- Ignition ON, install a 15-amp fused jumper wire between the control terminal A and 12 volts. Momentarily install a jumper wire between the control terminal B and ground. The door latch assembly should perform the LOCK/UNLOCK function.
- Reverse the jumper wires. The door latch assembly should perform the UNLOCK/LOCK function.
| ⇒ | If the function does not perform as specified, replace the door latch assembly. |
| ⇒ | If the function does not perform as specified, replace the door latch. |
Relay Test
- Ignition OFF, disconnect the appropriate relay.
- Test for 60-200 ohms between terminals 85 and 86.
- Test for infinite resistance between the following terminals:
- Test for less than 2 ohms between terminals 30 and 87A.
- Install a 3-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 ohms between terminals 30 and 87.
| ⇒ | If not within the specified range, replace the relay. |
| • | 30 and 86 |
| • | 30 and 87 |
| • | 30 and 85 |
| • | 85 and 87 |
| ⇒ | If less than the specified value, replace the relay. |
| ⇒ | If greater than the specified range, replace the relay. |
| ⇒ | If greater than the specified range, replace the relay. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM, DDM, or FPDM replacement, setup, and programming |
