System Operation Description:
Use this procedure under the following situation:
The PTO Switch ON Lamp is suspected of operating incorrectly.
Output 1
J1:30 (Output 1) can be used as an output for the PTO Switch ON Lamp or an output for the Low Coolant Level Warning Lamp. If the “Engine Monitoring Lamps” parameter is programmed to Warning Lamp, then output 1 is used for the PTO Switch ON Lamp. If the “Engine Monitoring Lamps” parameter is programmed to Option 1 and the “Coolant Level Lamp” parameter is programmed to “4-Pin” or “2 wire Float Sensor”, then output 1 is used for the low coolant level warning.
Note: The “PTO Configuration” must be programmed to Cab Switches, Remote Switches, or Remote Throttle to utilize the PTO Switch ON Lamp.
Electrical Connection of Lamps
One terminal of the PTO Switch is connected to the positive battery circuit. The other terminal is connected to the ECM at J1/P1:30.
The ECM provides a path to ground in order to turn the lamp ON.
Test Step 1. Inspect Electrical Connectors and Wiring
A. Thoroughly inspect the J1/P1 ECM connector, the firewall bulkhead connector, or the PTO Switch ON Lamp. Refer to Troubleshooting, “Electrical Connectors – Inspect” for details.
B. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the PTO Switch ON Lamp. Refer to Illustration 151.
C. Check the ECM connector (allen head screw) for the proper torque of 6.0 N·m (55 lb in).
D. Check the harness and wiring for abrasion and pinch points from the battery to the ECM.
Expected Result:
All connectors, pins and sockets should be completely coupled and/or inserted and the harness and wiring should be free of corrosion, abrasion or pinch points.
Results:
• OK – Proceed to Test Step 2.
• Not OK
Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.
STOP.
Test Step 2. Check for Normal Operation of the PTO Switch ON Lamp
A. Use the following procedure for the Output 1 (PTO Switch ON Lamp).
Connect the Caterpillar Electronic Technician (Cat ET) to the data link connector. Access the status screen that displays the “PTO Configuration” and the PTO ON/OFF Switch. The “PTO Configuration” must indicate Cab Switches, Remote Switches, or Remote Throttle. The “PTO Configuration” is not programmed to turn the PTO Switch ON Lamp to the ON position if the “PTO Configuration” indicates OFF.
If the “Engine Monitoring Lamps” parameter is programmed to Option 1 and the “Coolant Level Lamp” parameter is programmed to “4-Pin” or “2 wire Float Sensor”, then Output 1 will not function as a PTO Switch On Lamp. Refer to Troubleshooting, “Warning Lamp Circuit – Test”.
While the PTO Switch ON Lamp and the status of PTO ON/OFF Switch is being watched on Cat ET, turn the PTO On/Off Switch to the ON position and the OFF position. The PTO Switch ON Lamp should turn ON when the PTO On/Off Switch is in the ON position. Also, the PTO Switch ON Lamp should turn Off when the PTO On/Off switch is in the OFF position.
Expected Result:
The Lamp turns ON and the Lamp turns OFF per the above description.
Results:
• OK – The lamp appears to operating correctly at this time. STOP.
• Not OK – Proceed to Test Step 3.
Test Step 3. Test the PTO Switch ON Lamp Circuit.
A. Disconnect the J1/P1 ECM connector.
B. Fabricate a jumper wire 100 mm (4 inch) long.
Crimp a Deutsch pin to both ends of the wire.
C. Insert the jumper into P1:30.
D. Connect the other side of the jumper wire to P1:65 (-Battery).
E. Turn the ignition key switch to the ON position.
F. While the lamp is being watched, insert the jumper wire and remove the jumper wire.
Refer to Illustration 152.
Expected Result:
Result 1 The PTO Switch On Lamp turns ON while the jumper is connected to both sockets. Also, the PTO Switch On Lamp turns OFF when the jumper is removed from one of the sockets.
Result 2 The suspect lamp does not turn ON while the jumper is connected to both sockets.
Result 3 The lamp will stay ON while the ECM vehicle harness connector is disconnected.
Results:
• Result 1 – The PTO Switch ON Lamp circuit is functioning properly. Proceed to Test Step 4.
• Result 2 – The lamp did not turn ON. The vehicle’s lamp circuit is not functioning properly. The lamp is probably burned out or there is a problem in the wiring from the cab to either the ECM or the +Battery connection. Repair the lamp circuit or send the vehicle to the OEM dealer for repairs. STOP.
• Result 3
Repair: Perform the following diagnostic
procedure:
The circuit between the ECM and the lamp is shorted to chassis ground. Repair the circuit or send the vehicle to the OEM dealer for repairs. STOP.
Test Step 4. Check ECM Operation of the PTO Switch On Lamp
A. Disconnect the J1/P1 ECM connector.
B. Insert a breakout T between ECM connector J1 and ECM connector P1.
C. Connect one probe of the voltage test lamp to terminal 65 (-Battery). Connect the other probe of the voltage test lamp to terminal 52 (Unswitched +Battery) of the breakout T.
D. The test lamp should turn ON. If the test lamp does not turn on, either the test lamp is faulty or the wiring to the ECM is faulty. Continue with this step if the lamp turns ON.
E. Leave the voltage test lamp probe connected to terminal 52 (Unswitched +Battery).
F. Connect the other probe of the test lamp to terminal 30 (Output 1) of the breakout T.
Refer to Illustration 153.
G. Connect Cat ET to the data link connector.
Access the following display screens in order:
• “Diagnostics”
• “Diagnostic Test”
• “Special Test”
H. Activate the special test for the PTO Switch ON Lamp. Observe the voltage test lamp. The lamp should turn ON when the test is active. Also, the lamp should turn OFF when the test is inactive.
Expected Result:
The test lamp turns ON and the test lamp turns OFF per the above description.
Results:
• OK – The ECM is operating correctly. There is a problem in the vehicle wiring or the lamp. STOP.
• Not OK
Repair: Temporarily connect a test ECM. Ensure that the “PTO Configuration” of the test ECM matches the “PTO Configuration” of the suspect ECM. Check the ECM operation of the PTO Switch ON Lamp when the test ECM is installed. If the problem is resolved with the test ECM, reconnect the suspect ECM. If the problem returns with the suspect ECM, replace the ECM.
STOP.
