CAGE 4S8698 - Caterpillar

Illustration 3 g03323694
Terminal locations at the P2 ECM connector
(P2-69) Speed droop signal
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 connectors (P1), and (P2). Inspect all of the connectors in the harness from the engine interface connector to the speed control that are associated with the circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
C. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors, the engine interface connector, and the connector for the EMCP that are associated with the circuit.
D. Check the torque of the allen head screws for each of the ECM connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
E. Check the harness and the wiring for abrasion and for pinch points from the batteries to the ECM.
Connectors
Results: The connectors and wiring appear to be OK.
Proceed to Test Step 2
Results: The connectors and/or wiring are not OK.
Repair: Repair the wiring and/or the connectors. Replace parts, if necessary.
Verify that the repair eliminates the problem.
2. Check for Active Diagnostic Codes
A. Connect Caterpillar Electronic Technician (ET) to the service tool connector.
B. Restore the electrical power to the ECM.
C. Monitor the active diagnostic code screen on Cat ET. Check for an active 08 code for the throttle signal.
Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
D. Turn the main disconnect switch to the OFF position.
Codes
Results: No diagnostic codes are active.
Repair: If the above code has been logged, there may be an intermittent problem in the harness or in a connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" in order to troubleshoot intermittent electrical problems.
If a problem with the speed control circuit is suspected, proceed to Test Step 3
Results: A 08 diagnostic code is active at this time. The ECM has detected an erratic signal at the input for the throttle signal.
Proceed to Test Step 3
3. Check the Supply Voltage to the Speed Control
A. Restore the electrical power to the ECM.
B. Start the engine.
C. Measure the voltage between terminals +Battery and −Battery at the speed control.
D. Stop the engine. Turn the main disconnect switch to the OFF position.
24 3.0 VDC
Results: The engine started and the supply voltage is 24 3.0 VDC at the speed control. The speed control is receiving supply voltage.
Proceed to Test Step 4
Results: The supply voltage is not 24 3.0 VDC.
Repair: The supply voltage is not reaching the speed control. If the engine started, the control relay is receiving electrical power. There is a problem in the harness or the connectors between the output of control relay and the speed control. The problem may be in the ground circuit to the speed control.
Perform the following Test Steps:
1. Remove the electrical power from the ECM.
2. Remove the wire from the −Battery terminal at the speed control.
3. Check the resistance between the wire for the −Battery at the speed control and the battery negative