Test C: All Instrument Panel Illumination Does Not Dim

PINPOINT TEST C: ALL INSTRUMENT PANEL ILLUMINATION DOES NOT DIM

C1-C4:

C4-C6:

C6-C8:

C9:

Normal Operation
The smart junction box (SJB) monitors the input from the instrument panel dimmer switch by sending a voltage reference signal through circuit CLN27 (WH/BN) to the instrument panel dimmer switch. The return signal is sent through circuit RLN29 (WH/OG) back to the SJB. Based on the input from the instrument panel dimmer switch, the SJB sends a pulse-width modulated (PWM) 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.

The SJB also sends a message over the network to the audio unit, the DVD player, the climate control module, and the instrument cluster to indicate the backlighting intensity level. If the receiving module receives invalid backlighting data from the SJB for 5 seconds or less, the receiving module defaults the backlighting to the last setting.

If the receiving module does not receive the backlighting status message from the SJB or if the data received is deemed invalid for more than 5 seconds, the receiving module sets DTC U0140 in continuous memory (except the climate control module) and defaults the backlighting to full intensity.

DTC B2212 - is an on-demand DTC that sets when the SJB detects an out of range condition on the dimmer input switch circuit.

Possible Causes
- Circuit RLN29 (WH/OG) open, short to ground or voltage
- Circuit CLN27 (WH/BN) open, short to ground or voltage
- Instrument panel dimmer switch
- SJB