Test H: The Defrost System Will Not Shut Off Automatically

PINPOINT TEST H: THE DEFROST SYSTEM WILL NOT SHUT OFF AUTOMATICALLY

H1-H4:

H4-H6:

H6-H8:

H8-H9:

Normal Operation
For the hard top defrost system, the rear electronic module (REM) checks circuit 9-HB23 (BN/WH) for a ground. If circuit 9-HB23 (BN/WH) is grounded, the REM commands the hard top defrost system to operate when the heated rear window switch is pressed.

The rear battery junction box (BJB) heated rear window relay has voltage at all times. The heated rear window switch (part of the dual automatic temperature control (DATC) supplies a signal to the REM, which grounds the heated rear window relay and closes it in order to supply voltage to circuit 75-HB19 (YE/RD), which powers the heated rear window grid. The grid is grounded through circuit 31-HB19 (BK/BU). The rear BJB heated rear window relay remains closed, supplying voltage to the heated rear window grid for approximately 10 minutes or until the heated rear window switch is pressed again.

For the convertible top defrost system, the REM checks circuit 9-HB23 (BN/WH) for a ground. If circuit 9-HB23 (BN/WH) is not grounded, the REM commands the convertible top defrost system to operate when the heated rear window switch is pressed.

The auxiliary relay box heated rear window relay has voltage at all time. The heated rear window switch supplies a signal to the REM which grounds the auxiliary relay box heated rear window relay and closes it in order to supply voltage to circuit 75-HB20 (YE/GN), which powers the heated rear window grid.

The auxiliary relay box heated rear window relay remains closed, supplying voltage to the heated rear window grid for approximately 10 minutes or until the heated rear window switch is pressed again.

Possible Causes
- circuit 91S-HB23 (BN/WH) short to ground
- circuit 75-HB20 (YE/GN) short to voltage
- circuit 91-HB24 (BN) short to ground
- circuit 9-HB19 (BN/RD) short to voltage
- heated rear window switch
- rear BJB heated rear window relay
- auxiliary relay box heated rear window relay
- REM