F-20: Sensor Power Fault A common failure point can be the connector on the suspension pressure sensors. These connectors take a lot of abuse from pressure washing and occasionally short circuit or develop floating voltages from water and dirt intru- sion. The quickest way to fix these problems is to disconnect the two halves and blow out any debris and clean the contacts. The process of disconnecting and re-inserting a connector often clears up many problems. If a problem persists, check the crimps on the terminals for intermittent connection due to vibration and wear.
On the 930E’s, the most common cause for sensor power faults is a short in the harness coming from the back of the cab to the Aux/Junction box. This harness contains a splice for sensor power. This splice is approximately 305 mm (12 in.) from the connector and is exposed to vibration and dirt from the left tire. It may be possible to locate this splice and repair it. A single wire for circuit 39F carries 18v from the payload meter to the splice, where it branches out for each sensor. The 39F circuit from PLM II™ is over-current protected. If this circuit is shorted to ground, the payload meter will automatically shut off the 18v supply.
This will cause the payload meter to register faults for all the sensors. In general, check the voltages at the sensors. It may be possible to disconnect each sensor in the junction box to see where the short may be. If disconnecting all the sensors does not clear the fault, it is likely that the problem lies within the harness from the back of the cab to the control cabinet. Refer to the following page for the fault tree diagram. M20007.2 3/02 Payload Meter II™ Troubleshooting M20-43