Speed Signal The speed signal triggers the payload meter to display the time of day when the truck begins moving. If this does not happen or the payload meter does not count up the distance from the shovel after loading, the speed signal may be missing. This can be confirmed by checking the inputs to the payload meter. Refer to “Monitoring Input Sig- nals”. Verify the payload meter is not receiving a speed signal before following the troubleshooting fault tree. NOTE: The payload meter will ignore speed signal input if the brake lock appears to be on. Confirm the payload meter correctly reads the brake lock input.
930E Speed Signal On the 930E, the speed signal comes from a speed sensor mounted on the left-front wheel. Occasionally, this sen- sor is damaged by debris, impact during tire mounting, or misalignment during repair of the spindle. The wheel must be removed to replace the sensor. Since the sensor is an active device, it requires an 18v power supply to power the electronics that convert the electromagnetic pulses into signals for the payload meter. In addition, because the sensor is active and not just a simple coil, it is not possible to measure the resistance across the con- tacts of the harness to determine if the sensor has failed.
To troubleshoot, confirm that the 18v power supply is reaching the sensor. The speed signal can be monitored in the control cabinet to confirm the wiring from the sensor to the cabinet. Checking the signal at the back of the pay- load meter will confirm the wiring from the control cabinet. It is also possible to check the speed signal at the back of the payload meter to confirm the entire wiring route. A signal generator may be used at the wheel to generate a signal back to the payload meter. The speed signal input can be monitored from the payload meter using the pro- cedure outlined in “Monitoring Input Signals”. Adjusting the Speed Sensor: 1.
Align a tooth on the speed sensor gear with the tip of the speed sensor. 2. Check the distance between the speed sensor and gear tooth with a feeler gauge. 3. Adjust the gap to 0.060 in. (1.5 mm) and lock the sensor in place. 4. Rotate the wheel hub 180° and verify that the gap has remained within specifications. 730E/830E Speed Signal The speed signal for the 730E/830E model trucks comes from a passive speed sensor mounted on the left wheel motor. This signal travels on the 714/714A circuits to an isolation transformer in the control cabinet. From the transformer, the signal travels through the connector at the back of the cab up to the payload meter.
Confirm that the sensor at the wheel motor is working properly. This is a passive, coil-type speed sensor and its electrical integrity can be checked using an ohmmeter. Confirm the speed signal in the control cabinet at the trans- former. A signal generator may be used at the wheel motor to generate a signal back to the payload meter. The speed signal input can be monitored from the payload meter using the procedure outlined in “Monitoring Input Sig- nals”. HD1500/530M Speed Signal The speed signal runs from a speed sensor on the transmission output shaft to the PMC and to the payload meter. You can confirm the speed sensor by checking the speed input to the PMC.
Confirm the speed signal wiring from the PMC to the payload meter. The speed signal input can be monitored from the payload meter using the proce- dure outlined in “Monitoring Input Signals”. Refer to the following page for the fault tree diagram. M20007.2 3/02 Payload Meter II™ Troubleshooting M20-51