Pinpoint Test B: The Instrument Panel Illumination Does Not Dim
Instrument Cluster and Panel Illumination
Pinpoint Tests
Pinpoint Test B: The Instrument Panel Illumination Does Not Dim
Refer to Wiring Diagram Set 71, Cluster and Panel Illumination for schematic and connector information. Diagrams By Number
Normal Operation
With the parking lamps on, a voltage signal is supplied to the instrument panel dimmer switch through circuit 1036 (BN/WH) from the Smart Junction Box (SJB). The dimmer switch passes this voltage through a variable resistor and then returns the signal to the SJB on circuit 1035 (OG/RD). The SJB uses the return signal to determine the backlighting intensity desired by the operator. A Pulse-Width Modulation (PWM) signal is sent from the SJB to each of the dimmable backlights, maintaining the operator's desired level of lighting intensity.
The dimmable backlighting defaults to full intensity if the instrument panel dimmer switch or circuitry fails.
- DTC B1247 (Panel Dim Switch Circuit Open) - is a continuous and on-demand DTC that sets when the SJB detects a open circuit from the instrument panel dimmer switch circuitry.
- DTC B2132 (Dimmer Switch Circuit Short to Gnd) - is a continuous and on-demand DTC that sets when the SJB detects a short to ground on the instrument panel dimmer switch reference signal circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Instrument panel dimmer switch
- SJB
PINPOINT TEST B: THE INSTRUMENT PANEL ILLUMINATION DOES NOT DIM
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
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B1 MONITOR THE INSTRUMENT PANEL ILLUMINATION OPERATION
- With the parking lamps on, rotate the dimmer switch from maximum brightness to minimum brightness.
- Monitor all instrument panel illumination sources for correct operation.
- Do the Instrument Cluster (IC) and Audio Control Module (ACM) dim correctly?
Yes
GO to B2.
No
For the IC, INSTALL a new IC. TEST the system for normal operation.
For the ACM, REMOVE the Audio Control Module (ACM). SEND it to an authorized repair facility. TEST the system for normal operation.
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B2 CHECK THE SJB INSTRUMENT PANEL DIMMER SWITCH PIDs
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: SJB DataLogger.
- Turn the parking lamps on.
- Monitor the SJB instrument panel dimmer switch PID (PANELINT) while rotating the instrument panel dimmer switch from the lowest setting to the highest setting.
- Do the SJB instrument panel dimmer switch PIDs agree with the instrument panel dimmer switch position?
Yes
GO to B7.
No
GO to B3.
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B3 CHECK THE INSTRUMENT PANEL DIMMER SWITCH OPERATION
- Disconnect: Instrument Panel Dimmer Switch C2298.
- Carry out the instrument panel dimmer switch component test.
- Does the instrument panel dimmer switch pass the component test?
Yes
GO to B4.
No
INSTALL a new instrument panel dimmer switch. CLEAR the DTCs. REPEAT the self-test.
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B4 CHECK CIRCUITS 1035 (OG/RD), 1036 (BN/WH) AND 1405 (LB/BK) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: SJB C2280b.
- Measure the voltage between the SJB, harness side and ground as follows:
- Is any voltage indicated?
Yes
REPAIR the circuit in question. TEST the system for normal operation.
No
GO to B5.
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B5 CHECK CIRCUITS 1035 (OG/RD), 1036 (BN/WH) AND 1405 (LB/BK) FOR A SHORT TO GROUND
- Measure the resistance between the SJB, harness side and ground as follows:
- Are the resistances greater than 10,000 ohms?
Yes
GO to B6.
No
REPAIR the circuit in question. TEST the system for normal operation.
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B6 CHECK CIRCUITS 1035 (OG/RD), 1036 (BN/WH) AND 1405 (LB/BK) FOR AN OPEN
- Disconnect: Illumination Dimmer Switch C2298.
- Measure the resistance between the SJB, harness side and the instrument panel dimmer switch, harness side as follows:
- Are the resistances less than 5 ohms?
Yes
GO to B7.
No
REPAIR the circuit in question. TEST the system for normal operation.
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B7 CHECK FOR CORRECT SJB OPERATION
- Disconnect all the SJB connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB 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 SJB. 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. CLEAR the DTCs. REPEAT the self-test.
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