Test A

PINPOINT TEST A: ONE OR MORE MODULE-CONTROLLED ILLUMINATION SOURCE(S) IS INOPERATIVE

Test A1:

Test A2-A3:

Test A3 Continued:

Normal Operation
The headlamp switch supplies the instrument cluster with the headlamp switch position status. The instrument panel dimmer switch provides the instrument cluster with the dimming control status through signal circuit 8-LE10 (WH/BK) and return circuit 9-LE10 (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 instrument panel dimmer switch position. The FEM is supplied with illumination power through circuit 29S-DK22 (OG/YE) 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 pulse width modulation (PWM) power to the auxiliary junction box through circuit 64S-LH2 (BU/RD) and then to the dimmable backlighting sources through circuits 64S-LK21 (BU/BK) and 64S-LK1 (LB). Circuit 64S-LK1 (LB) is then spliced and sent to the dimmable backlighting sub-sources through circuits 64-LK18 (BU/RD), 64S-LE10 (BU/YE), 64S-LH26 (BU/BK), 64S-LH45 (BU/OG), and 64S-LK29 (BU/RD). For the fixed backlighting system, when the key is in the ON position, the auxiliary junction box sends the rear electronic module (REM) a voltage signal through circuit 29S-DK31 (OG/BK). The REM, in turn, sends B+ voltage to the fixed backlighting sources through circuit 7-LH1 (YE) for 100% illumination density.

Possible Causes
- circuit 7-AJ7 (YE/RD) open or shorted to ground
- circuit 7-AJ18 (YE/VT) open
- circuit 7-LH28 (YE) open or shorted to ground
- circuit 7-LH42 (YE/RD) open or shorted to ground
- circuit 64-HC6 (BU) open or short to ground
- circuit 64-HC9 (BU/BK) open
- circuit 64-LK15 (BU/WH) open
- circuit 64-LK18 (BU/RD) open
- circuit 64S-LE10 (BU/YE) open
- circuit 64S-LH26 (BU/BK) open
- circuit 64S-LH45 (BU/OG) open
- circuit 64S-LK21 (BU/BK) open
- circuit 31-AJ80A (BK/OG) open or short to power
- circuit 31-HC6 (BK) open or short to power
- circuit 31-HC9 (BK) open or short to power
- circuit 31-LE10 (BK) open or short to power
- circuit 31-LE15 (BK/GN) open or short to power
- circuit 31-LH26 (BK) open or short to power
- circuit 31-LH28 (BK/YE) open or short to power
- circuit 31-LH42 (BK/BU) open or short to power
- circuit 31-LH45 (BK) open or short to power
- circuit 31-LK21 (BK) open or short to power
- circuit 31S-PG24 (BK/OG) open or short to power