Power Door Locks Inoperative. Cadillac Seville

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2001 🢒 Seville - RHD 🢒 Body and Accessories 🢒 Doors 🢒 Power Door Locks Inoperative

Diagnostic Aids

The following may cause erratic door lock operation.

•	A high resistance or an open in the ground circuit of the power door lock switch.

•	An intermittent or poor connection of the wiring and connectors.

If door lock operation is erratic, thoroughly inspect the wiring and connectors. An incomplete inspection of the wiring and connectors may result in misdiagnosis and unneccessary parts replacement with the reappearance of the malfunction. If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Rear door lock actuator control circuits are normally grounded by the rear door modules when the locks are not being operated. However, if one of these control circuits is shorted to ground, the RRDR MDL fuse will open and DTCs U1162 and U1163 will be set current when the door locks are operated. All rear door functions will be inoperative. If the control circuits between the rear door modules and rear door lock actuators are found to be intact, it will be neccessary to determine which rear door lock actuator has a control circuit internally shorted to ground. This can be done by disconnecting one of the rear door modules, replacing the damaged RRDR MDL fuse, and repeating the instructions in Step 3. When the RRDR MDL fuse does not open while repeating the Step 3 instructions, the door lock actuator that was disconnected is the cause of the malfunction.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

This step determines if a rear door lock actuator has a control circuit shorted to ground. This condition could open the RRDR MDL fuse when the rear door lock actuator is actuated and cause DTCs U1162 and U1163 to be simultaneously set current.

This step determines if the door modules recognize the lock switch inputs.

However, if the lock switch ground circuit has failed, the scan tool could still display switch inputs transitioning to Lock and Unlock as if there were no failure. This is due to the fact that the lock switch can find an alternate path to ground through the switch illumination circuit when the headlamps are turned Off. By turning the headlamps On in this step, the possibility of overlooking an open lock switch ground circuit as the cause of the malfunction is eliminated.

This step determines if the unlock control circuit to the door lock actuator may be the cause of the malfunction.

If the test lamp is already illuminated before operating the lock switch, test the unlock control circuit for a short to battery positive voltage.

This step determines if the lock control circuit to the door lock actuator may be the cause of the malfunction.

If the test lamp is already illuminated before operating the lock switch, test the lock control circuit for a short to battery positive voltage.

This step eliminates the logic ground circuit of the inoperative door module as the cause of the malfunction.

This step will determine which control circuit is shorted to ground. However, if the external hard wire circuits between the rear door modules and rear door lock actuators are found to be intact, it will be neccessary to determine which of the rear door lock actuators has a control circuit internally shorted to ground. This can be done by disconnecting one of the rear door modules, replacing the damaged RRDR MDL fuse, and repeating the instructions in Step 3.

This step directs you to, either inspect for poor connections at the passenger door module, or, at the driver door switch assembly (DDSA) as a pre-requisite to replacing the passenger door module or driver door switch assembly (DDSA). This is because lock switch signals for the driver door are detected and processed by the driver door switch assembly (DDSA), while lock switch signals for the passenger door are detected and processed by the passenger door module.

This step directs you to, either replace the passenger door module or driver door switch assembly (DDSA). This is because lock switch signals for the driver door are detected and processed by the driver door switch assembly (DDSA), while lock switch signals for the passenger door are detected and processed by the passenger door module.

Step

Action

Yes

Schematic Reference: Door Lock/Indicator Schematics

DEFINITION: This test assumes that all DTCs have been diagnosed.

Did you perform the Door Systems Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Door Systems

Verify that the Power Door Locks Inoperative complaint is present.

Does the power door lock system operate as described in the Description and Operation?

Go to Diagnostic Aids

Go to Step 3

Turn OFF the ignition.
Install a scan tool.
Select the display DTCs function on the scan tool.
Close all of the vehicles doors.
Turn On the ignition, with the engine OFF.
Operate both front door lock switches to both the Lock and Unlock positions.

Did DTCs U1162 and U1163 simultaneously set current when you operated the lock switches?

Go to Step 14

Go to Step 4

Turn ON the headlamps switch.
Operate the lock switches to the following positions:

•	Both the Lock and Unlock positions for the front door lock switches.

•	Lock position only for the rear door lock switches.

With the scan tool, observe each door lock switch parameter in the Driver Door Module, Inputs list.

Did the parameters change to both the Lock and Unlock states for the front door lock switches and, to the Lock state for the rear door lock switches?

Go to Step 7

Go to Step 5

Turn OFF the ignition.
Disconnect the harness connector of the appropriate door lock switch.
Turn On the ignition, with the engine OFF.
With a test lamp connected to a good ground, probe the following switch circuits:

•	For an inoperative front door lock, probe the Lock signal circuit, and the Unlock signal circuit.

•	For an inoperative rear door lock, probe the Lock signal circuit.

Did the test lamp illuminate while probing any of the circuits?

Go to Step 15

Go to Step 6

Connect a 3 amp fused jumper wire between the inoperative signal circuit and the ground circuit of the lock switch harness connector.
With the scan tool, observe the appropriate door lock switch parameter.

Does the scan tool display the inoperative state?

Go to Step 16

Go to Step 10

Disconnect the harness connector of the inoperative door lock actuator.
Connect a test lamp between the Unlock control circuit of the harness connector and a good ground.
Operate either one of the front door lock switches to Unlock.

Does the test lamp flash once upon operating the switch to Unlock?

Go to Step 8

Go to Step 11

Connect a test lamp between the Lock control circuit of the harness connector and a good ground.
Operate either one of the front door lock switches to Lock.

Does the test lamp flash once upon operating the switch to Lock?

Go to Step 9

Go to Step 11

Connect a test lamp between the Unlock control circuit and the Lock control circuit of the harness connector.
Operate either one of the front door lock switches to both Lock and Unlock.

Does the test lamp flash once upon operating the switch to LOCK and once upon operating the switch to Unlock?

Go to Step 19

Go to Step 13

Test the signal and ground circuits of the appropriate door lock switch for an open or a high resistance.