GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The remote control door lock receiver (RCDLR) communicates with the body control module (BCM) through the keyless entry serial data circuit. When any button on the keyless entry transmitter is pressed, the transmitter sends a signal to the RCDLR. The RCDLR sends a lock or unlock request to the BCM, depending on which button is pressed on the transmitter. On vehicles equipped with content theft deterrent (CTD), the RCDLR may also send a panic alarm request to the BCM. The BCM receives the message and performs the appropriate function. The BCM also uses the keyless entry serial data circuit in order to communicate with the RCDLR when programming transmitters.

Conditions for Running the DTC

The system voltage is at least 9.0 volts and no more than 16.0 volts.

Conditions for Setting the DTC

The BCM will set DTC 8 whenever the BCM detects a lack of communication with the RCDLR, including any of the following conditions:

    • The RCDLR B+ supply is open or shorted to ground.
    • The RCDLR ground circuit is open or has high resistance.
    • The BCM detects an open in the keyless entry serial data circuit.
    • The BCM detects a short to ground in the keyless entry serial data circuit.
    • The BCM detects a short to voltage in the keyless entry serial data circuit.

Action Taken When the DTC Sets

The keyless entry system will not operate. (The power sliding door will continue to operate with the keyless entry transmitter.)

Conditions for Clearing the DTC

A DTC will clear when the fault is no longer present and the DTCs are cleared as described in Diagnostic Trouble Code (DTC) Clearing. Refer to On-Board Diagnostic Features in Body Control Systems.

Diagnostic Aids

Perform a visual inspection for loose or poor connections at all related components. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Tests for an open, poor connection, or short to ground in the keyless entry serial data circuit. A measurement of B+ indicates good circuit continuity.

  2. Tests for an short to voltage in the keyless entry serial data circuit. Illumination of an INCANDESCENT test lamp indicates a short to voltage. A LED circuit tester may give an incorrect indication.

Step

Action

Value(s)

Yes

No

Schematic Reference: Keyless Entry Schematics

1

Did you perform the body control module (BCM) Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Body Control System in Body Control System

2

Press each button of the transmitter one at a time.

Does the system operate normally?

--

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the remote control door lock receiver (RCDLR).
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the battery positive voltage circuit of the RCDLR and the RCDLR ground circuit.

Does the test lamp illuminate?

--

Go to Step  4

Go to Step 12

4

Connect a test lamp between the battery positive voltage circuit of the RCDLR and the RCDLR ground circuit.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 13

5

With a DMM, measure the voltage from the keyless entry serial data circuit of the RCDLR to a good ground.

Does the voltage measure near the specified value?

B+

Go to Step 6

Go to Step 7

6

  1. Turn OFF the ignition.
  2. Connect a test lamp between the keyless entry serial data circuit of the RCDLR and a good ground.
  3. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

--

Go to Step 11

Go to Step 9

7

Test the keyless entry serial data circuit for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 8

8

Test the keyless entry serial data circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 10

9

Inspect for poor connections at the harness connector of the RCDLR. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 15

10

Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 14

11

Repair the short to voltage in the keyless entry serial data circuit. Refer to Circuit Testing or Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

12

Repair the open, high resistance , or short to ground in the battery positive voltage circuit of the RCDLR. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

13

Repair the open or high resistance in the RCDLR ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

14

Important: Perform the BCM programming procedure when replacing the BCM.

Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Did you complete the repair?

--

Go to Step 16

--

15

Important: Perform the RCDLR programming procedure when replacing the RCDLR. Refer to Transmitter Programming .

Replace the RCDLR. Refer to Remote Control Door Lock Receiver Replacement .

Did you complete the repair?

--

Go to Step 16

--

16

  1. Clear the BCM DTCs. Refer to On-Board Diagnostic Features in Body Control System.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK