Diagnostic Routine H

Diagnostic Routine H

Diagnostic Overview

The Keyless Entry Keypad Illumination Is Inoperative Or Always On

Refer to Wiring Diagram Set 117 for schematic and connector information Electrical Diagrams.

Normal Operations and Fault Conditions

When any keypad button is pressed the BCM (Body Control Module) sends voltage to the keyless entry keypad LEDs (Light-emitting Diodes) on the illumination circuit to assist the driver in entering an access code at night. The keyless entry keypad has a separate ground circuit for the LEDs (Light-emitting Diodes).

DTC Fault Trigger Conditions






Visual Inspection and Diagnostic Pre-checks

- Keyless entry keypad

Pinpoint Test

1. CHECK THE KEYLESS ENTRY KEYPAD ILLUMINATION

1. Ignition OFF.

2. Check the keyless entry keypad illumination.

Is the keyless entry keypad illumination always on?








2. CHECK THE KEYLESS ENTRY KEYPAD INPUT TO THE BCM (Body Control Module)

1. Using a scan tool, monitor the BCM (Body Control Module) PIDs (Parameter Identifications) KYPD_BTN_1/2, KYPD_BTN_7/8, and KYPD_BTN_9/0.

2. Touch several keyless entry keypad buttons while viewing the PIDs (Parameter Identifications).

Do the PIDs (Parameter Identifications) display active when the corresponding button is touched?








3. CHECK THE BCM (Body Control Module) DTCs (Diagnostic Trouble Codes) FROM THE SELF-TEST

1. Using a scan tool, perform the BCM (Body Control Module) self-test.

Is DTC (Diagnostic Trouble Code) B121A:11 present?








4. CHECK THE KEYLESS ENTRY KEYPAD FOR A SHORT TO GROUND

1. Disconnect: Keyless Entry Keypad.

2. Using a scan tool, clear the BCM (Body Control Module) DTCs (Diagnostic Trouble Codes).

3. Using a scan tool, perform the BCM (Body Control Module) self-test.

Is DTC (Diagnostic Trouble Code) B121A:11 present?








5. CHECK THE KEYPAD ILLUMINATION OUTPUT CIRCUIT FOR A SHORT TO GROUND

1. Ignition OFF.

2. Disconnect: BCM (Body Control Module) C2280C.

3. Measure:





Is the resistance greater than 10,000 ohms?








6. CHECK THE KEYPAD ILLUMINATION OUTPUT CIRCUIT FOR REFERENCE VOLTAGE
NOTE: The BCM (Body Control Module) sends out a constant reference voltage on circuit CPK28 (WH/RD) for its own circuit diagnostics. This voltage is 11 volts +/- 1 volt.

1. Disconnect Keyless Entry Keypad.

2. Measure:





Are 11 volts (+/- 1 volt) present?








7. CHECK FOR BCM (Body Control Module) OUTPUT
NOTE: This pinpoint test checks for a voltage increase above the reference voltage checked in the previous pinpoint test when the keypad lamp is active commanded on.

1. Using a scan tool, view BCM (Body Control Module) PIDs (Parameter Identifications).

2. While active commanding the BCM (Body Control Module) PID (Parameter Identification) (KEY_PAD_LMP) ON, measure:





Does the voltage increase at least 1 volt greater than the reference voltage?








8. CHECK THE KEYPAD ILLUMINATION OUTPUT CIRCUIT FOR AN OPEN

1. Ignition OFF.

2. Disconnect BCM (Body Control Module) C2280C.

3. Measure:





Is the resistance less than 3 ohms?








9. CHECK THE KEYPAD ILLUMINATION OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE

1. Disconnect BCM (Body Control Module) C2280C.

2. Ignition ON.

3. Observe the keypad illumination.

Is the keypad still illuminated?








10. CHECK FOR CORRECT BCM (Body Control Module) OPERATION

1. Ignition OFF.

2. Disconnect and inspect all BCM (Body Control Module) connectors.

3. Repair:

- corrosion (install new connector or terminals- clean module pins)
- damaged or bent pins- install new terminals/pins
- pushed-out pins- install new pins as necessary

4. Reconnect all BCM (Body Control Module) connectors. Make sure they seat and latch correctly.

5. Operate the system and determine if the concern is still present.

Is the concern still present?