Power Top

The content of this article reflects changes called for in TSB 26-01-97.

CIRCUIT OPERATION
The power top system uses a switch, a hydraulic pump motor, two power top relays, and a Power Top Inhibit (PTI) relay which is located in the Power Distribution Center (PDC)

Power for the coil and contact sides of the PTI relay is supplied on circuit F20. This circuit is HOT in the RUN position only and protected by a 5 amp fuse located in the junction block.

Ground for the coil side of the relay is supplied by the Body Control Module (BCM) on circuit G43. The BCM controls the ground path for the relay based on vehicle speed. If vehicle speed is above 10 mph the BCM removes the ground path for the relay and the power top will not operate.

When vehicle speed is below 10 mph the contacts in the relay are CLOSED and circuits F20 and P118 are connected. Circuit P118 connects from the relay to the power top switch.

Down Operation
When the operator selects top DOWN, circuit P118 is connected to circuit P5. The P5 circuit connects from the switch to the power top DOWN relay Voltage flowing through the coil side of the relay causes the contacts in the relay to CLOSE connecting circuits A25 and P4.

The A25 circuit is protected by a 40 Amp fuse located in cavity 11 of the PDC.

Circuit P4 connects from the relay to the pump motor. Voltage flows through the motor to circuit P3. The P3 circuit provides the ground path for the motor back to the relay assembly. Internal to the relay circuit P3 connects to circuit Z1.

Up Operation
When the operator selects top UP, circuit F20 is connected to circuit P6. The P6 circuit connects from the switch to the power top UP relay. Voltage flowing through the coil side of the relay causes the contacts in the relay to CLOSE connecting circuits A25 and P3.

The A25 circuit is protected by a 40 Amp fuse located in cavity 11 of the PDC.

Circuit P3 connects from the relay to the pump motor. Voltage flows through the motor to circuit P4. The P4 circuit provides the ground path for the motor back to the relay assembly. Internal to the relay circuit P4 connects to circuit Z1.