System Operation Description:
Use the following procedure to troubleshoot the electrical system if a problem is suspected with the switch circuits or if another procedure has sent you here.
The following switches may be used:
- Maintenance clear switch (NO)
- Torque limit switch (NO)
- Ether starting aid switch (NO)
- PTO interrupt switch (NC)
- Remote shutdown switch (NO)
- Intermediate engine speed switch (NO)
- Overspeed verify switch (NO)
- PTO enable switch (NO)
- PTO ramp up switch (NO)
- PTO ramp down switch (NO)
Switch circuits may have problems such as faulty wiring, faulty switches, or faulty connectors.
The switches are normally open or normally closed.
Schematic for the normally open switch and the normally closed switch
Typical switch inputs
Test Step 1. Check the Electrical Connectors and the Wiring
- Remove electrical power from the Electronic Control module (ECM).
Illustration 2 g01428866
(1) J1/P1 connectors
(2) J2/P2 connectors
- Thoroughly inspect the J1/P1 and the J2/P2 ECM connectors. Thoroughly inspect the connections for the suspect switch. Refer to Troubleshooting, “Electrical Connectors – Inspect”.
Illustration 3 g01428883
P1 terminals for the various switches
(P1-13) Ether starting aid switch
(P1-8) Remote shutdown switch
(P1-24) Intermediate engine speed switch
(P1-32) Overspeed verify switch
(P1-20) PTO enable switch
(P1-25) PTO ramp up switch or set switch
(P1-15) PTO ramp down switch or resume switch
Illustration 4 g01428901
P2 terminals for the various switches
(P2-31) Maintenance clear switch
(P2-16) Torque limit switch
(P2-26) PTO interrupt switch
- Perform a 45 N (10 lb) pull test on each of the wires in the circuit for the suspect switch.
- Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, “Electrical Connectors – Inspect” for the correct torque values.
- Check the allen head screw on the customer connector for the proper torque. Refer to Troubleshooting, “Electrical Connectors – Inspect” for the correct torque value.
- Check the harness and wiring for abrasions and for pinch points.
All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring are free of corrosion, of abrasion or of pinch points.
- OK – The wiring and connectors are OK. Proceed to Test Step 2.
- Not OK – There is a problem with the wiring and/or a connector.Repair: Repair the wiring and/or the connector. Replace parts, if necessary. Ensure that all of the seals are properly connected. Verify that the repair eliminates the problem.
Test Step 2. Test the Switch for Proper Operation
- Disconnect the J1/P1 and the J2/P2 ECM connectors.
- Refer to Table 1. Determine the terminal for the suspect switch.
Table 1 Terminals for the Switch Inputs Name of the Switch ECM Terminals Connector Terminals Maintenance clear switch P2-31 12 Torque limit switch P2-16 2 Ether starting aid switch P1-13 38 PTO interrupt switch P2-26 19 Remote shutdown switch P1-8 27 Intermediate engine speed switch P1-24 28 Overspeed verify switch P1-32 40 PTO enable switch P1-20 29 PTO ramp up switch or set switch P1-25 30 PTO ramp down switch or resume switch P1-15 39
- Connect a meter lead to the ECM terminal for the suspect switch. Connect the other meter lead to negative ground.
Note: Wiggle the harnesses during the following measurements in order to reveal any intermittent short condition.
- Measure the resistance between the P1 or the P2 ECM terminal for the suspect switch and negative ground.
- Activate the switch and measure the resistance again.
When the switch is open, the resistance measurement indicates an open circuit. When the switch is closed, the resistance measurement is less than ten Ohms.
- OK – One resistance measurement indicates an open circuit. The other resistance measurement is less than ten Ohms. The switch is operating correctly. The wiring does not have a short circuit or an open circuit.Repair: Operate the engine and check the switch for proper operation.If the switch does not operate correctly, there may be a short circuit between the circuit for the suspect switch and another circuit. Carefully reinspect the components. Refer to Troubleshooting, “Electrical Inspectors – Inspect”. Locate the short circuit and make repairs.
- Not OK – Both resistance measurements indicate an open circuit or both resistance measurements are less than ten Ohms. There is a problem with the circuit for the switch.Repair: The problem could be in the switch, in the wiring, or in a connector.Carefully reinspect the components. Refer to Troubleshooting, “Electrical Inspectors – Inspect”.If the inspection does not identify the faulty component, replace the switch and test the switch again.If the problem is not resolved, repair the wiring or the connector. Replace parts, if necessary. Verify that the problem is resolved.