BUCKET AS-HEAVY DUTY ROCK 4989997 - Caterpillar

For this troubleshooting procedure, the "Desired Speed Input" configuration parameter can be set to "PWM" input or "0-5 Volt" input.The engine ECM will only monitor the status of the input signal for the PWM and 0-5 Volt desired speed inputs.The engine ECM does not supply the power and ground for the PWM or 0-5 Volt speed control circuits.If using the EMCP 4.3 and either the 0-5 Volt analog output or the PWM speed control feature, then the EMCP 4.3 will monitor the status of those outputs in relation to power and ground circuit health.If an external speed control source device is used, refer to that devices troubleshooting procedure.If using the EMCP 4.3 CAN desired speed input, refer to Troubleshooting, "Data Link - Test".The value of the current, frequency, or voltage corresponds to a range of desired engine speeds between minimum high idle and maximum high idle. The "Minimum Engine High Idle Speed" and the "Maximum Engine High Idle Speed" are set with the "Service/Configuration" screen of Cat ET. For more information, refer to Troubleshooting, "Configuration Parameters".The most likely causes of a diagnostic code for this circuit are a poor connection or a problem in a wiring harness. The next likely cause is a problem with a component. The least likely cause is a problem with the ECM.
Illustration 1 g06189909
For the complete circuit details, refer to the full schematic.
Table 2
Troubleshooting Test Steps Values Results
1. Inspect the Electrical Connectors and the Wiring
A. Turn the main disconnect switch to the OFF position.
B. Thoroughly inspect the connectors. Refer to Troubleshooting, "Electrical Connectors-Inspect" for additional information.
C. Perform a 45 N (10 lb) pull test on the connector wires.
D. Check the harness for abrasions and pinch points.
Connectors and Wiring
Result: The connectors and wiring appear to be OK.
Proceed to Test Step 2.
Result: There is a problem with the connectors and/or wiring.
Repair: Repair or replace the connectors or wiring. Ensure that all the seals are properly in place and ensure that the connectors are coupled.
If the problem is not resolved, proceed to Test Step 2.
2. Check for Codes
A. Connect Cat® Electronic Technician (ET) to the service tool connector.
B. Determine if a code is active or logged.
Codes
Result: Any of the following codes are active or logged:
- 29-4
- 91-4
- 91-8
Proceed to Test Step 3.
Result: Any of the following codes are active or logged:
- 29-3
- 91-3
Proceed to Test Step 7.
3. Check the Wiring for an Open Circuit
A. Ensure that the engine control is in the OFF/RESET position. Ensure that the electrical power is removed from the engine and the speed control device.
B. Remove the signal wire at the Engine Interface Connector (EIC), that carries the (PWM or analog 0-5 Volt) desired speed input signal to the engine ECM.
C. Perform one of the following:
- For the 91-4 and 91-8 disconnect the A-C1 connector from the ECM.
- For the 29-4 diagnostic disconnect the A-C2 connector from the ECM.
D. Measure the resistance between the following terminals at the removed ECM connector:
- For the 91-4 and 91-8 codes, terminal 66 of the A-C1 ECM