Symptom Table Missing Body-Up Signal The payload meter starts a new haul cycle after the body comes down from dumping the last haul cycle. Each new haul cycle starts at the dump. Without a body-up signal, the payload meter does not know that a new haul cycle has started. The payload meter will not record new haul cycles without the body-up signal. This is the most com- mon sign that the signal is missing. The body-up input signal is received from a magnetic switch located on the inside of the truck frame forward the pivot pin of the truck body. This is the same switch typically used for input to the drive system.
When the body is down, the switch closes and completes the circuit to 71-Control Power. 24vdc indicates the body is down. Open cir- cuit indicates that the body is up. This input can be checked using the "Monitoring Input Signals" procedure. M20-36 Payload Meter II™ Troubleshooting M20007.2 3/02 PROBLEM PROBABLE CAUSE Payload meter is not recording haul cycles. Broken or missing body-up signal. The body up signal triggers the PLM II™to start a new haul cycle. Check using the "Monitoring Input Signals" procedure. Only one haul cycle in memory. Display shows payload all the time. Broken or missing speed signal. Check using the "Monitoring Input Signals" procedure.
Display does not show time when the truck is trav- eling. No distance or speed information is recorded in the haul cycle data. Payload meter does not 'count up' while driving away from the shovel. Payload meter will not calibrate. F-18 fault Missing alternator R-terminal signal. Troubleshoot signal or make modification to eliminate signal. Refer to the “F-18: R-Terminal, Oil Pressure Sig- nals” on the following page. F20 - F28 faults flashing Shorted sensor power or ground. Troubleshoot wiring. Refer to the "Shorted 18v Sensor Power Supply" fault tree in this section. Pressure sensor value drifts up or down erratically.