Use this procedure under the following situation:
Use this procedure to determine if the circuit for the starting aid switch is operating correctly.
The following background information is related to this procedure:
The ECM can use various inputs in a number of ways. The inputs depend on the parameter programming. Certain features are available on several different inputs. The configuration for the switch must match the actual switch installation in order for the switch to function properly.
"Starting Aid On/Off Switch"
A starting aid feature that is controlled by the ECM is available with NOV99 and newer software.
The starting aid system does not require a switch for automatic operation. A switch can be installed in order to allow the operator to override the automatic starting aid. If a switch is installed and the "starting aid On/Off switch" parameter is programmed to the corresponding switch input, the switch will control the starting aid system. The starting aid system will automatically enable the starting aid output when the switch is in the ON position. However, the conditions must require the use of a starting aid. When the switch is in the OFF position, the starting aid system will not function. If the "Starting Aid On/Off Switch" parameter is programmed to "None" (default), this feature is not used. The "Starting Aid On/Off Switch" parameter should be programmed to one of the inputs (J1/P1:7, J1/P1:47, J1/P1:6, J1/P1:46). Also, the switch circuit should be connected to the same input option.
Note: The wiring for your particular application may be slightly different. The sensor common circuits are used interchangeably by the OEM of the vehicle. The following circuits are common within the ECM:
- The "Input Sensor Common 1" is terminal 18.
- The "Input Sensor Common 2" is terminal 3.
- The "AP Sensor/Switch Sensor Common" is terminal 5.
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| Illustration 1 | g00682699 |
Schematic for the Starting Aid Switch | |
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| Illustration 2 | g00682618 |
Terminal Locations for the ECM | |
Test Step 1. Check the Electrical Connectors and the Wiring
- 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 circuit for the starting aid switch.
- Check the ECM connector (allen head screw) for the proper torque of 6.0 N·m (55 lb in).
- Check the harness and the wiring for abrasion and 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 should be free of corrosion, abrasion or 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.STOP
Test Step 2. Check the "Starting Aid On/Off Switch" Status on ET
- Connect the Caterpillar Electronic Technician (ET) to the cab data link connector.
- Turn the ignition key switch to the ON position.
- Operate the switch in the ON and OFF positions.
- View the "Starting Aid On/Off Switch" status on ET.
- If the "Starting Aid On/Off Switch" status indicates "Not Installed", then the "Starting Aid On/Off Switch" parameter has not been programmed.
Expected Result:
The status screen should indicate ON if the switch is turned on. The status screen should indicate OFF if the switch is off.
Results:
- OK - The switch is operating normally. Continue troubleshooting if the original condition is not resolved.STOP
- Not OK - The ECM is not reading the "Switch Status" change. Proceed to Test Step 3.
Test Step 3. Check the Switch Circuit for the ECM
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| Illustration 3 | g00682624 |
Connector for the Breakout T | |
- Turn the ignition key switch to the OFF position.
- Install a 70 terminal breakout T to the ECM vehicle harness 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 the input terminal for the starting aid switch of the breakout T. Connect the other end of the jumper wire to terminal 5 in the breakout T. Terminal 5 is AP Sensor/Switch Common.
Note: Refer to the programmed selection of the "starting aid On/Off switch" parameter. This reference will display the appropriate input.
- Connect ET to the cab 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 ET.
Expected Result:
The switch status changes to "ON" with the jumper wire in place. The switch status changes to "OFF" when the jumper wire is removed.
Results:
- OK - The ECM is functioning properly at this time. Proceed to Test Step 4.
- Not OK - The ECM is not functioning properly.
Repair: Perform the following diagnostic procedure:
- Temporarily connect a test ECM. Only connect ECM harness J1/P1.
- Recheck for an +5 V diagnostic code when the engine harness is disconnected.
- 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
Test Step 4. Insert a Jumper Wire at the Switch
- Turn the ignition key switch to the OFF position.
- Reconnect the ECM vehicle harness 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 between the two switch terminals of the starting aid switch.
- 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 ET.
Expected Result:
The switch status changes to "ON" with the jumper wire in place. The switch status changes to "OFF" when the jumper wire is removed.
Results:
- OK -
Repair: Perform the following diagnostic procedure:Replace the switch.Verify that the repair eliminates the problem.
STOP
- Not OK - There is a problem in the wire harness between the starting aid 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 position.
- Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.
- Locate the socket for the starting aid switch that is suspect in the engine side of the ECM 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 ECM 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 ET.
Expected Result:
The switch status changes from "ON" with the jumper wire in place. The switch status changes to "OFF" when the jumper wire is removed.
Results:
- OK - 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
- Not OK - 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