Diagnostic Instructions

DTC Descriptors

DTC B3127: LF Door Only, Unlock Circuit Low

DTC B3128: LF Door Only, Unlock Circuit High

DTC B3132: All Unlock Circuit Low

DTC B3133: All Unlock Circuit High

DTC B3137: All Door Lock Circuit Low

DTC B3138: All Door Lock Circuit High

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Switch B+	1, 2, 3	1, 2, 3	--	--
Door Lock Switch B+	1, 2, 3	1, 2, 3	--	--
Door Lock Control	B3137	B3138	B3138	--
Door Unlock Control	B3132	B3133	B3133	--
Driver Door Unlock Relay Control	B3127	B3128	B3128	--
Passenger Door Lock Switch Unlock Supply Voltage	2, 3	2, 3	2, 3	--
Passenger Door Lock Switch Lock Supply Voltage	1	1	1	--
Door Latch Control	1, 2, 3	1, 3	1, 3	--
Liftgate Latch Control	1, 2, 3	1, 3	1, 3	--
Ground	--	1, 2, 3	1, 2, 3	--
1. Door Locks Inoperative 2. Driver Door Unlock Inoperative 3. Door Unlock Inoperative

Circuit/System Description

The body control module (BCM) controls the door lock, passenger door unlock and driver door unlock relays. Voltage is applied to the appropriate relay through the door lock/unlock control circuit when the BCM senses a door lock/unlock switch activation or a keyless entry lock or unlock command.

Conditions for Running the DTC

The system voltage must be between 9-16 volts.

Conditions for Setting the DTC

B3127

The BCM detects a short to ground in the driver door unlock relay control circuit while commanding the driver door unlock relay.

B3128

The BCM detects an open in the driver door unlock relay control circuit.

B3132

The BCM detects a short to ground in the door unlock control circuit while commanding the door unlock relay.

B3133

The BCM detects an open in the door unlock control circuit.

B3137

The BCM detects a short to ground in the door lock control circuit while commanding the door lock relay.

B3138

The BCM detects an open in the door lock control circuit.

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Reference Information

Schematic Reference

Connector End View Reference

Vehicle Access Connector End Views

Description and Operation

Electrical Information Reference

Scan Tool Reference

Circuit/System Testing

1. Ignition OFF, disconnect the appropriate relay.
2. Test for less than 1 ohm between the relay coil ground circuit and ground.

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

3. Connect a test lamp between the relay coil control circuit and the relay coil ground circuit.
4. Command the appropriate relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always OFF, test the relay coil 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 relay coil control circuit for a short to voltage. If the circuit tests normal, replace the BCM

5. If all circuits test normal, test or replace the appropriate relay.

Component Testing

Relay Test

1. Ignition OFF, disconnect the applicable relay.
2. Test for 60-200 ohms of resistance between terminals 85 and 86.

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

3. Test for infinite resistance between the following terminals:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If less than infinite resistance, replace the relay.

4. Test for less than 2 ohms of resistance between terminals 30 and 87A.

⇒	If greater than 2 ohms, replace the relay.

5. Install a 3-amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Measure for less than 2 ohms of resistance between terminals 30 and 87.

⇒	If greater than 2 ohms, replace the relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.