Use this procedure to troubleshoot the electrical system if a problem is suspected with a sensor supply or if any one of the diagnostic codes in Table 1 is active or easily repeated.
| Diagnostic Codes Table | |||
|---|---|---|---|
| Code and Description | Flash Code | Conditions which Generate this Code | System Response |
| 241-00 5 Volt Open Circuit | 21 | The supply voltage is normal. The rack signal is below 0.3 VDC. The boost signal, oil pressure signal and the coolant temperature signal are below 0.5 VDC. The engine rpm is greater than 0. | The code is active and the code is logged. All sensors are set to default values. |
| 241-01 5 Volt Short Circuit | 21 | The supply voltage for the sensors is less than 3 VDC or the supply voltage is greater than 7.0 VDC. | The code is active and the code is logged. All sensors are set to default values. |
| 241-02 8 Volt Open Circuit | 21 | The supply voltage for the sensors is normal. The rack signal is equal to 5 VDC and the coolant temperature signal is less than 0.6 VDC. | The code is active and the code is logged. All sensors are set to default values. |
| 241-03 8 Volt Short Circuit | 21 | The supply voltage for all of the sensors is less than 6.4 VDC or the supply voltage is greater than 9.6 VDC. | The code is active and the code is logged. All sensors are set to default values. |
The Electronic Control Module (ECM) supplies a regulated voltage of 5.0 ± 0.2 VDC to the following sensors:
- Engine oil pressure sensor
- Atmospheric pressure sensor
- Intake manifold pressure sensor
The ECM supplies a regulated voltage of 8.0 ± 0.4 VDC and 5.0 ± 0.2 VDC to the rack position sensor.
The supply voltage for the sensors is routed from the ECM to terminal (A) of each sensor connector. The sensor return for the sensors is routed from the ECM to terminal (B) of each sensor connector. The ECM provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.
Note: The sensors are not protected from overvoltage. A short from the supply line to the +Battery may damage the sensors. Repair the sensor supply and check for any active sensor diagnostic codes in order to determine if a sensor has failed.
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| Illustration 1 | g01638014 |
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| Illustration 2 | g01638357 |
(10) + 8 VDC (30) + 5 VDC (35) Analog return | |
Test Step 1. Inspect the Electrical Connectors and the Wiring
- Remove electrical power from the ECM.
- Thoroughly inspect the customer connector J17/P17. 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 for the coolant level sensor.
- 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 - The connectors and wiring are OK. 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. Check Sensor Supply Voltages at the ECM
- Reconnect all connectors.
- Turn the engine control switch to the ON position.
- Measure the voltage betweenP14-30 and P14-35.
- Measure the voltage betweenP14-10 and P14-35.
Expected Result:
The voltage measures 5.0 ± 0.25 VDC between P14-30 and P14-35. The voltage measures 8.0 ± 0.4 VDC between P14-10 and P14-35.
Results:
- Ok - The voltage measures 5.0 ± 0.25 VDC between P14-30 and P14-35. The voltage measures 8.0 ± 0.4 VDC between P14-10 and P14-35. Proceed to Test Step 3.
- NOT OK - The voltage did not measure 5.0 ± 0.25 VDC between P14-30 and P14-35.
Repair: Check the supply voltage to the ECM. Refer to Troubleshooting, "Electrical Power Supply - Test".
If the voltage is correct, proceed to Test Step 5.
- NOT OK - The voltage did not measure 8.0 ± 0.4 VDC between P14-10 and P14-35.
Repair: Check the supply voltage to the ECM. Refer to Troubleshooting, "Electrical Power Supply - Test".
If the voltage is correct, proceed to Test Step 4.
Test Step 3. Check Sensor Supply Voltage at the 5 Volt Sensors
- Turn the engine control switch to the ON position.
- Measure the sensor supply voltage between pin (A) and pin (B) of the following sensor connectors: inlet manifold pressure sensor, engine oil pressure sensor and atmospheric pressure sensor.
- Measure the sensor supply voltage between pin (C) and pin (B) of the rack sensor connector.
Expected Result:
The voltage is 5.0 ± 0.25 VDC for each measurement.
Results:
- OK - The voltage is 5.0 ± 0.25 VDC for each measurement. Proceed to Test Step 4.
- NOT OK - The voltage is not 5.0 ± 0.25 VDC for each measurement. Supply voltage is present at the ECM but not at the sensor.
Repair: There is a problem in the harness. There may be a problem in a connector. Repair the wire and/or the connector, when possible. Replace parts, if necessary. Verify that the problem is resolved.
STOP
Test Step 4. Check Sensor Supply Voltage at the 8 Volt Sensors.
- Turn the engine control switch to the ON position.
- Measure the sensor supply voltage between pin (A) and pin (B) of the coolant temperature sensor connector.
- Measure the sensor supply voltage between pin (A) and pin (B) of the coolant level sensor connector.
- Disconnect the rack sensor connector J11/P11.
- Measure the sensor supply voltage between pin (A) and pin (B) of the rack sensor connector.
Expected Result:
The voltage is 8.0 ± 0.40 VDC for each measurement.
Results:
- OK - The voltage is 8.0 ± 0.40 VDC for each measurement.
Repair: The supply voltage is reaching the sensor. Refer to Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent.
STOP
- NOT OK - The voltage is not 8.0 ± 0.40 VDC for each measurement.
Repair: The supply voltage is present at the ECM but not at the sensor. There is an open circuit in the harness or in the connector. Repair the harness or replace the harness.
STOP
Test Step 5. Check the ECM
- Reconnect P14 and leave all the sensors disconnected.
- Turn the engine control switch to the ON position.
- Measure the voltage betweenP14-30 and P14-35.
- Measure the voltage betweenP14-10 and P14-35.
Expected Result:
The voltage measures 5.0 ± 0.25 VDC between P14-30 and P14-35. The voltage measures 8.0 ± 0.4 VDC between P14-10 and P14-35.
Results:
- OK - The voltage measures 5.0 ± 0.25 VDC between P14-30 and P14-35. The voltage measures 8.0 ± 0.4 VDC between P14-10 and P14-35.
Repair: There is a problem with the harness. Repair the harness or replace the harness.
STOP
- NOT OK - The voltage did not measure 5.0 ± 0.25 VDC between P14-30 and P14-35.
Repair: The ECM is not producing the correct voltage. Replace the ECM. Refer to Troubleshooting, "ECM - Replace" for further information.
STOP
- NOT OK - The voltage did not measure 8.0 ± 0.4 VDC between P14-10 and P14-35.
Repair: The ECM is not producing the correct voltage. Replace the ECM. Refer to Troubleshooting, "ECM - Replace" for further information.
STOP