The rack solenoid is used to move the engine fuel rack. The rack solenoid is actuated by a spring to the fuel OFF position. The rack solenoid moves into the ON position when voltage is applied.
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| Illustration 1 | g01643973 |
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| Illustration 2 | g01643993 |
(10) + 8 VDC (22) Solenoid ground (23) Rack solenoid (30) + 5 VDC (35) Analog return (40) Rack position | |
| Diagnostic Codes Table | |||
|---|---|---|---|
| Code and Description | Flash Code | Conditions which Generate this Code | System Response |
| 23-02 Engine Power Excessive |
48 |
The actual rack position is greater than the desired rack position. Excessive power is being generated by the engine. |
The code is logged. |
| Factory passwords are required to clear this code. | |||
| 23-05 Rack BTM current low |
43 |
The actual rack position is not proportional to the desired rack position. There are no sensor supply voltage faults. The arm of the rack solenoid is not in the desired position. |
The code is logged. |
| The ECM uses the engine speed to govern the engine. The rack sensor signal is ignored. The rack limit is set to 13.5 mm (0.53 inch). |
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| 23-06 Rack BTM current high |
43 |
The actual rack position is not proportional to the desired rack position. There are no sensor supply voltage faults. The arm of the rack solenoid is not in the desired position. |
The code is logged. |
| The ECM uses the engine speed to govern the engine. The rack sensor signal is ignored. The rack limit is set to 13.5 mm (0.53 inch). |
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Test Step 1. Inspect the Electrical Connectors and the Wiring Harness
- Remove electrical power from the ECM.
- Thoroughly inspect the J6/P6 connector for the rack solenoid (BTM) and the J11/P11 connector for the rack position sensor. Inspect the ECM connector J14/P14. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit.
- Check the allen head screw on the ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
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 - 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. Proceed to Test Step 2.
- NOT OK - There is a problem with the connectors and/or the wiring.
Repair: 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.Verify that the repair eliminates the problem.
STOP
Test Step 2. Remove the Rack Solenoid and Inspect the Rack Solenoid
- Turn the engine control switch to the OFF position.
- Remove the rack solenoid.
- Make sure that the rack and the rack servo have free movement.
- Inspect the arm of the rack solenoid for damage and signs of binding in the sleeve of the servo.
Expected Result:
The arm of the rack solenoid is not damaged or the arm of the rack solenoid does not show signs of binding.
Results:
- OK - The arm of the rack solenoid is not damaged or the arm of the rack solenoid does not show signs of binding. Proceed to Test Step 3.
- NOT OK - The arm of the rack solenoid is damaged or the arm of the rack solenoid shows signs of binding.
Repair: Repair the arm of the rack solenoid or replace the arm of the rack solenoid.
STOP
Test Step 3. Sweep Test for the Rack Solenoid
- Connect Caterpillar Electronic Technician (ET) to the service tool connector.
- Turn the engine control switch to the ON position.
- Activate the sweep test for the rack solenoid and observe the arm of the rack solenoid.
Note: Some applications may have an auxiliary system that can interrupt power to the ECM. These systems may need to be temporarily bypassed in order to perform the sweep test.
- Deactivate the sweep test.
Expected Result:
The arm of the rack solenoid moves smoothly in a clockwise direction. Once the arm moves slightly past the dot on the face plate, the arm moves back to the OFF position.
Results:
- OK - The arm of the rack solenoid moves smoothly in a clockwise direction. Once the arm moves slightly past the dot on the face plate, the arm moves back to the OFF position. The rack is functioning properly.STOP
- NOT OK - The arm of the rack solenoid does not move smoothly in a clockwise direction. Once the arm moves slightly past the dot on the face plate, the arm does not move back to the OFF position. Proceed to Test Step 4.
Test Step 4. Check the Resistance of the Rack Solenoid
- Turn the engine control switch to the OFF position.
- Disconnect the rack solenoid connector J6/P6.
- Measure the resistance between pin (A) and pin (B) of the rack solenoid connector.
Expected Result:
The resistance is between 0.5 Ohms and 1.5 Ohms.
Results:
- OK - The resistance is between 0.5 Ohms and 1.5 Ohms. Proceed To Test Step 5.
- NOT OK - The resistance is not between 0.5 Ohms and 1.5 Ohms.
Repair: Replace the rack solenoid.
STOP
Test Step 5. Check the Harness for Shorts
- Disconnect the ECM connector J14/P14.
- Disconnect the rack solenoid connector J6/P6.
- Measure the resistance between pin (A) and pin (B) of the J6 connector.
- Measure the resistance between pin (A) and engine ground.
- Measure the resistance between pin (B) and engine ground.
Expected Result:
The resistance is greater than 20,000 Ohms.
Results:
- OK - The resistance is greater than 20,000 Ohms. Proceed to Test Step 6.
- NOT OK - The resistance is less than 20,000 Ohms.
Repair: Repair the harness or replace the harness.
STOP
Test Step 6. Check Resistance through the Harness
- Connect Deutsch socket terminals at each end to a 152 mm (6 inch) wire.
- Connect the wire to pin (A) and pin (B) of connector J6.
- Measure the resistance between pin (23) and pin (22) of connector P14.
Expected Result:
The resistance is less than 10 Ohms.
Results:
- OK - The resistance is less than 10 Ohms. Proceed to Test Step 7.
- NOT OK - The resistance is greater than 10 Ohms.
Repair: There is excessive resistance in the harness. Repair the harness or replace the harness.
STOP
Test Step 7. Check Voltage at the ECM During the Sweep Test
- Reconnect all connectors.
- Turn the engine control switch to the ON position.
- Activate the sweep test for the rack.
- Measure the voltage between pin (23) and pin (22) of connector P14 during the sweep test for the rack.
Note: If the voltage increases to 11 to 12 VDC, recheck the harness for an open circuit.
Expected Result:
The voltage starts at 0 VDC and increases to 3.6 ± 0.3 VDC. The voltage then decreases back to 0 VDC.
Results:
- OK - The voltage starts at 0 VDC and increases to 3.6 ± 0.3 VDC. The voltage then decreases back to 0 VDC. Proceed to Test Step 8.
- NOT OK - The voltage does not start at 0 VDC and the voltage does not increase to 3.6 ± 0.3 VDC. The voltage does not decrease back to 0 VDC.
Repair: Check the supply voltage to the ECM. Refer to Troubleshooting, "Electrical Power Supply - Test". If the voltage is correct, replace the ECM. Refer to Troubleshooting, "ECM - Replace" for further information.
STOP
Test Step 8. Check the Voltage to the Rack Solenoid During the Sweep Test
- Activate the sweep test.
- Measure the voltage between pin (A) and pin (B) of connector P6 during the sweep test.
- Observe the arm of the rack solenoid during the sweep test.
- Deactivate the sweep test.
Expected Result:
The voltage starts at 0 VDC and increases to 3.6 ± 0.3 VDC. The voltage then decreases back to 0 VDC.
Results:
- OK - The voltage starts at 0 VDC and increases to 3.6 ± 0.3 VDC. The voltage then decreases back to 0 VDC.
Repair: Replace the solenoid.
STOP
- NOT OK - The voltage does not start at 0 VDC and the voltage does not increase to 3.6 ± 0.3 VDC. The voltage does not decrease back to 0 VDC.
Repair: The correct voltage is at the ECM but not at the solenoid. Repair the harness or replace the harness.
STOP