Pinpoint Test B: All Dimmable Illumination Does Not Dim
Instrument Cluster and Panel Illumination
Pinpoint Tests
Pinpoint Test B: All Dimmable Illumination Does Not Dim
Refer to Wiring Diagram Set 71, Cluster and Panel Illumination for schematic and connector information. Diagrams By Number
Normal Operation
The Smart Junction Box (SJB) monitors the input from the instrument panel dimmer switch by sending a voltage signal to the instrument panel dimmer switch. The return signal is sent back to the SJB. Based on the input, the SJB sends a pulse-width modulated voltage signal to the dimmable illumination sources. If the SJB detects a concern with the circuitry to the instrument panel dimmer switch, the SJB defaults the backlighting to a full intensity level.
- DTC B2121 (Illumination Switch Short to Battery) - a continuous and on-demand DTC that may set when the SJB detects an open or short to voltage on the illumination dimmer switch input circuit.
- DTC B2132 (Dimmer Switch Circuit Short to Gnd) - a continuous and on-demand DTC that may set when the SJB detects a short to ground on the dimmer switch input circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Instrument panel dimmer switch
- SJB
PINPOINT TEST B: ALL DIMMABLE 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 CHECK THE INSTRUMENT PANEL DIMMER SWITCH
- Ignition OFF.
- Disconnect: Instrument Panel Dimmer Switch C2298.
- Carry out the instrument panel dimmer switch component test.
- Is the instrument panel dimmer switch OK?
Yes
GO to B2.
No
INSTALL a new instrument panel dimmer switch. REFER to Instrument Panel Dimmer Switch Service and Repair. TEST the system for normal operation.
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B2 CHECK THE INSTRUMENT PANEL DIMMER SWITCH RETURN CIRCUIT FOR A SHORT TO VOLTAGE
- Disconnect: SJB C2280d.
- Ignition ON.
- Measure the voltage between the instrument panel dimmer switch C2298-4, circuit CLN17 (BN), harness side and ground.
- Is any voltage present?
Yes
REPAIR circuit CLN17 (BN) for a short to voltage. TEST the system for normal operation.
No
GO to B3.
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B3 CHECK THE INSTRUMENT PANEL DIMMER SWITCH INPUT CIRCUIT FOR A SHORT TO VOLTAGE
- Measure the voltage between the instrument panel dimmer switch C2298-6, circuit CLN27 (WH/BN), harness side and ground.
- Is any voltage present?
Yes
REPAIR circuit CLN27 (WH/BN) for a short to voltage. TEST the system for normal operation.
No
GO to B4.
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B4 CHECK THE INSTRUMENT PANEL DIMMER SWITCH RETURN CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the instrument panel dimmer switch C2298-4, circuit CLN17 (BN), harness side and the SJB C2280d-19, circuit CLN17 (BN), harness side; and between the instrument panel dimmer switch C2298-4, circuit CLN17 (BN), harness side and ground.
- Is the resistance less than 5 ohms between the instrument panel dimmer switch and the SJB and greater than 10,000 ohms between the instrument panel dimmer switch and ground?
Yes
GO to B5.
No
REPAIR circuit CLN17 (BN) for an open or short to ground. TEST the system for normal operation.
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B5 CHECK THE INSTRUMENT PANEL DIMMER SWITCH INPUT CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- Measure the resistance between the instrument panel dimmer switch C2298-6, circuit CLN27 (WH/BN), harness side and the SJB C2280d-18, circuit CLN27 (WH/BN), harness side; and between the instrument panel dimmer switch C2298-6, circuit CLN27 (WH/BN), harness side and ground.
- Is the resistance less than 5 ohms between the instrument panel dimmer switch and the SJB and greater than 10,000 ohms between the instrument panel dimmer switch and ground?
Yes
GO to B6.
No
REPAIR circuit CLN27 (WH/BN) for an open or short to ground. TEST the system for normal operation.
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B6 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. REFER to Body Control Systems. 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.
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