Test D

PINPOINT TEST D: THE INSTRUMENT CLUSTER ILLUMINATION IS INOPERATIVE

Test D1-D2:

Normal Operation
The headlamp switch supplies the instrument cluster with the headlamp switch position status. The dimmer switch provides the instrument cluster with the dimmer control status through signal circuit 8-LE1O (WH/BK) and return circuit 9-LE1O (BN/YE). The instrument cluster sends the illumination message to the front electronic module (FEM) over the standard corporate protocol (SCP) communication network, circuits 4-EG8 (GY/VT) and 5-EG8 (BU/WH), based upon the dimmer switch position. The FEM is supplied with illumination power through circuit 29S-DK22 whenever the switched system power (SSP) is energized. When the headlamp switch is in the PARK, HEADLAMP, or AUTOLAMP ON position, the instrument cluster sends the FEM an illumination message and the FEM, in turn, provides a pulse width modulation (PWM) power to the interior auxiliary junction box through circuit 64S-LH5 (BU/YE). The interior auxiliary junction box separates the PWM power and supplies it to joint connector 3 through circuit 64S-LH1 (BU) and from joint connector 3 to the instrument cluster through circuit 64S-LK29 (BU/RD). The instrument cluster is grounded by circuit 31-A11 (BK).

Possible Causes
- instrument cluster
- circuit 31-A11 (BK) open
- circuit 64S-LK29 (BU/RD) open or shorted