Pinpoint Test A: All Dimmable Illumination Does Not Increase/Decrease Brightness
Instrument Cluster and Panel Illumination
Pinpoint Test A: All Dimmable Illumination Does Not Increase/Decrease Brightness
Refer to Wiring Diagram Set 71, Cluster and Panel Illumination for schematic and connector information Electrical Diagrams.
Normal Operation
The instrument panel dimmer switch is a rocker style switch with 2 inputs to the Body Control Module (BCM) to increase or decrease the backlighting illumination. When the instrument panel dimmer switch is pressed up or down, a ground signal is routed to the BCM (Body Control Module).
Based on the ground signal input from the instrument panel dimmer switch, the BCM (Body Control Module) sends a message over the network to the modules with backlighting output indicating the backlighting intensity level, and provides voltage to the hard-wired dimmable illumination sources.
- DTC B134E:23 (Switch Illumination Adjustment Control: Signal Stuck low)- a continuous and on-demand DTC that sets when the BCM (Body Control Module) detects the instrument panel dimmer switch is stuck or held low for more than 2 minutes or the increase or decrease control circuits are shorted to ground. If the instrument panel dimmer switch is stuck low the BCM (Body Control Module) defaults the backlighting illumination to full backlighting intensity.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Instrument panel dimmer switch
- BCM (Body Control Module)
PINPOINT TEST A : ALL DIMMABLE ILLUMINATION DOES NOT INCREASE/DECREASE BRIGHTNESS
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
A1 CHECK THE RECORDED RESULTS FROM THE BCM (Body Control Module) ON-DEMAND SELF-TEST
- Ignition OFF.
- Review the recorded results from the BCM (Body Control Module) on-demand self-test.
Is DTC B134E:23 present?
Yes
GO to A2.
No
GO to A4.
A2 CHECK THE INSTRUMENT PANEL DIMMER SWITCH FOR A SHORT TO GROUND
- Disconnect: Instrument Panel Dimmer Switch C2298.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: BCM (Body Control Module) Self-Test.
- Clear the DTCs and repeat the BCM (Body Control Module) self-test.
Is on-demand DTC B134E:23 still present?
Yes
GO to A3.
No
INSTALL a new instrument panel dimmer switch. REFER to Instrument Panel Dimmer Switch Service and Repair. TEST the system for normal operation.
A3 CHECK THE INSTRUMENT PANEL DIMMER SWITCH INPUT CIRCUITS FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: BCM (Body Control Module) C2280E.
- Measure the resistance between the instrument panel dimmer switch C2298-3, circuit CLN56 (BN/VT), harness side and ground; and between the instrument panel dimmer switch C2298-7, circuit CLN55 (YE/VT), harness side and ground.
Are the resistances greater than 10,000 ohms?
Yes
GO to A7.
No
REPAIR the circuit in question for a short to ground. CLEAR the DTCs. REPEAT the self-test.
A4 CHECK THE INSTRUMENT PANEL DIMMER SWITCH
- Disconnect: Instrument Panel Dimmer Switch C2298.
- NOTE: For this step, the PID should indicate "DIMMER" each time the fused jumper wire is connected.
For the illumination decrease function, while monitoring the BCM (Body Control Module) PID IP_DIMMER_SW, connect and disconnect a fused jumper wire between the instrument panel dimmer switch C2298-3, circuit CLN56 (BN/VT), harness side and the instrument panel dimmer switch C2298-4, circuit GD115 (BK/GY), harness side.
- NOTE: For this step, the PID should indicate "BRIGHTER" each time the fused jumper wire is connected.
For the illumination increase function, while monitoring the BCM (Body Control Module) PID IP_DIMMER_SW, connect and disconnect a fused jumper wire between the instrument panel dimmer switch C2298-7, circuit CLN55 (YE/VT), harness side and the instrument panel dimmer switch C2298-4, circuit GD115 (BK/GY), harness side.
Does the PID indication agree with the fused jumper wire position?
Yes
INSTALL a new instrument panel dimmer switch. REFER to Instrument Panel Dimmer Switch Service and Repair. TEST the system for normal operation.
No
GO to A5.
A5 CHECK THE INSTRUMENT PANEL DIMMER SWITCH GROUND CIRCUIT
- NOTE: For this step, the PID should indicate "DIMMER" each time the fused jumper wire is connected to C2298-3, and "BRIGHTER" each time the fused jumper wire is connected to C2298-7.
While monitoring the BCM (Body Control Module) PID IP_DIMMER_SW, connect and disconnect a fused jumper wire between the instrument panel dimmer switch C2298-3, circuit CLN56 (BN/VT), harness side and ground; and between the instrument panel dimmer switch C2298-7, circuit CLN55 (YE/VT), harness side and ground.
Does the PID indication agree with the fused jumper wire position?
Yes
REPAIR circuit GD115 (BK/GY) for an open. TEST the system for normal operation.
No
GO to A6.
A6 CHECK THE INSTRUMENT PANEL DIMMER SWITCH DIM UP AND DIM DOWN CIRCUITS FOR AN OPEN
- Ignition OFF.
- Disconnect: BCM (Body Control Module) C2280E.
- Measure the resistance between the instrument panel dimmer switch C2298-3, circuit CLN56 (BN/VT), harness side and the BCM (Body Control Module) C2280E-11, circuit CLN56 (BN/VT), harness side.
- Measure the resistance between the instrument panel dimmer switch C2298-7, circuit CLN55 (YE/VT), harness side and the BCM (Body Control Module) C2280E-12, circuit CLN55 (YE/VT), harness side.
Are the resistances less than 5 ohms?
Yes
GO to A7.
No
REPAIR the circuit in question for an open. TEST the system for normal operation.
A7 CHECK FOR CORRECT BCM (Body Control Module) OPERATION
- Connect all disconnected connectors.
- Disconnect all the BCM (Body Control Module) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the BCM (Body Control Module) connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new BCM (Body Control Module). TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.