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 modulated (PWM) signal is sent from the SJB to each of the dimmable backlights, maintaining the operators desired level of lighting intensity.

• 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 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 dimmer switch reference signal circuit.

The dimmable backlighting defaults to full intensity if the instrument panel dimmer switch or circuitry fails.

This pinpoint test is intended to diagnose the following:

• Wiring, terminals or connectors
• Instrument panel dimmer switch
• SJB