3A3-72560-0 Tohatsu PTT SWITCH

Illustration 1 g01152403
Typical circuit schematic for the PTO engine shutdown switch
The return wire may be connected to P1-3, P1-5, or P1-18.
Note: The PTO engine shutdown switch may also be connected to P1/J1-7 Input 4. The parameter "PTO Engine Shutdown Switch" must be programmed to "P1/J1:7".Test Step 1. Inspect Electrical Connectors and Wiring
Illustration 2 g01152420
Pin locations on ECM connector
(P1-3) Sensor common 2
(P1-7) PTO engine shutdown (switch can be connected to pin 7 or to pin 23
(P1-23) PTO engine shutdown (switch can be connected to pin 7 or to pin 23
Thoroughly inspect the ECM vehicle harness connector J1/P1, the connectors, and the firewall bulkhead connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the suspect switch circuit.
Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Check the harness and the wiring for abrasion and for pinch points from the battery to the ECM. Then, check from the ignition key switch to the ECM. Refer to Illustration 2 for terminal locations for the ECM.Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - Proceed to Test Step 2.
Not OK - Repair the wiring and connectors or replace the wiring or the connectors. Ensure that all of the seals are properly connected. Verify that the repair eliminates the problem.STOPTest Step 2. Check the Switch Status on Caterpillar Electronic Technician (ET)
Connect Cat ET to the data link connector.
Turn the ignition key switch to the ON position.
Operate the switch in the ON position and the OFF position.
View the switch status on Cat ET.
If the switch status indicates "Not Installed", the parameter "PTO Engine Shutdown Switch" has not been programmed. Expected Result:The status screen indicates "ON" when the switch is turned ON. The status screen indicates "OFF" when the switch is OFF.Results:
Yes - The switch is operating normally. Continue troubleshooting if the original condition is not resolved.STOP
No - The ECM is not reading the change in the status of the switch. Proceed to Test Step 3.Test Step 3. Check the Switch Circuit for the ECM.
Illustration 3 g01152428
Breakout T
(3) Sensor common 2
(7) PTO engine shutdown (switch can be connected to pin 7 or to pin 23
(23) PTO engine shutdown (switch can be connected to pin 7 or to pin 23
Turn the ignition key switch to the OFF/RESET position.
Install a breakout T to the ECM connector J1/P1.
Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.
Insert the jumper wire into terminal 7 or terminal 23 of the breakout T. Connect the other end of the jumper wire to terminal 3 in the breakout T. Terminal 3 is sensor common.
Verify that Cat ET is connected to the data link connector.
Turn the ignition key switch to the ON position.
Alternately remove the jumper wire and then insert the jumper wire from terminal 5. At the same time, monitor the status screen on the electronic service tool. Expected Result:The status of the switch changes to "ON" with the jumper wire in place. The status of the switch changes to "OFF" when the jumper wire is removed.Results:
Yes - The ECM is functioning properly at this time. Proceed to Test Step 4.
No - The ECM is not functioning properly.Repair: Perform the following repair:
Temporarily connect a test ECM.
Remove all jumpers and replace all connectors.
Recheck the system for active diagnostic codes.
Repeat the test step.
If the problem is resolved with the test ECM, reconnect the suspect ECM.
If the problem returns with the suspect ECM, replace the ECM.
Verify that the repair eliminates the problem. STOPTest Step 4. Insert a Jumper Wire at the Switch.
Turn the ignition key switch to the OFF/RESET position.
Reconnect the ECM vehicle harness connector J1/P1.
Fabricate a jumper wire 100 mm (4 inch) long. Install a Deutsch pin to both ends of the wire.
Insert the jumper wire between the two switch terminals.
Turn the ignition key switch to the ON position.
Alternately remove the jumper wire and then insert the jumper wire at the switch terminals. At the same time, watch the status screen on Cat ET. Expected Result:The status of the switch changes to "ON" with the jumper wire in place. The status of the switch changes to "OFF" when the jumper wire is removed.Results:
Yes - The status is correct.Repair: Replace the switch.Verify that the repair eliminates the problem.STOP
No - There is a problem in the wire harness between the switch and the ECM. Proceed to Test Step 5.Test Step 5. Insert a Jumper Wire at the Bulkhead Connector.
Turn the ignition key switch to the OFF/RESET position.
Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.
Locate the suspect terminal on the engine side of the bulkhead connector.
Insert the wire jumper pin between the switch socket and the sensor common connection. Install the jumper wire on the engine side of the bulkhead connector.
Turn the ignition key switch to the ON position.
Alternately connect and then disconnect the jumper wire. At the same time, monitor the status screen on the electronic service tool. Expected Result:The status of the switch changes from "ON" with the jumper wire in place. The status of the switch changes to "OFF" when the jumper wire is removed.Results:
Yes - The problem is in the vehicle wiring between the bulkhead connector and the switch. Inspect the vehicle wiring and then repair the vehicle wiring. Otherwise, send the vehicle to the OEM dealer for repair. Verify that the original condition is resolved.STOP
No - The problem is in the vehicle wiring between the bulkhead connector and the ECM. Inspect the vehicle wiring and then repair the vehicle wiring. Otherwise, send the vehicle to the OEM dealer for repair. Verify that the original condition is resolved. STOP