The digital sensor supply in the Electronic Control Module (ECM) supplies 8.0 ± 0.5 VDC to the throttle position sensor.
The digital sensor supply is output short circuit protected. The ECM is protected from a short to ground and a short to +Battery condition. The digital sensor is not protected.
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| Illustration 1 | g00829434 |
Schematic | |
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| Illustration 2 | g01007781 |
P1 ECM connector | |
Test Step 1. Inspect Electrical Connectors and Wiring
- Turn the keyswitch to the OFF/RESET position.
- Thoroughly inspect the J1/P1 ECM connector, the J61/P61 machine connector, the J403/P403 throttle position sensor connector and all other connectors in the circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Expected Result:
All connectors, pins, and sockets are completely inserted and coupled. The harness and wiring are free of corrosion, of abrasion, and of pinch points. All connections and grounds are tight and free of corrosion.
Results:
- OK - The connectors and the wiring appear to be OK. Proceed to Test Step 2.
- Not OK - There is a problem with the connectors and/or the wiring.
Repair: Repair the circuit.Verify that the repair eliminates the problem.
STOP
Test Step 2. Check for Shorts in the Harness from the ECM to the Throttle Position Sensor
- Disconnect the J1/P1 ECM connector and the J403/P403 throttle position sensor connector.
- Measure the resistance between P1:4 (+8 VDC) and engine ground.
- Measure the resistance between P1:4 (+8 VDC) and P1:5 (Return).
- Leave the J1/P1 ECM connector and the throttle position sensor disconnected.
Expected Result:
The resistance is greater than 20,000 Ohms for each measurement.
Results:
- OK - The resistance is greater than 20,000 Ohms for each measurement. Proceed to Test Step 3.
- Not OK - There is a short between the ECM and the sensor.
Repair: Repair the circuit.
STOP
Test Step 3. Check for Open Circuits in the Harness Between the ECM and the Throttle Position Sensor
- Install a jumper wire between P1:4 (+8 VDC) and P1:5 (Return).
Note: The J1/P1 ECM connector and the throttle position sensor should still be disconnected.
- Measure the resistance between terminal A (+8 VDC) and terminal B (Return) of the P403 throttle position sensor connector on the wiring harness.
Expected Result:
The resistance is less than 10 Ohms.
Results:
- OK - The resistance is less than 10 Ohms.
Repair: Remove the jumper wire and reconnect the J1/P1 ECM connector. Leave the throttle position sensor disconnected.
Proceed to Test Step 4.
- Not OK - There is an open circuit in the wiring harness between the sensor and the ECM.
Repair: Repair the circuit.Verify that the repair eliminates the problem.
STOP
Test Step 4. Check the Digital Sensor Supply Voltage at the Sensor Connector
- Turn the keyswitch to the ON position.
- Measure the voltage across terminal A (+8 VDC) and terminal B (Return) of the P403 throttle position sensor connector on the wiring harness.
Expected Result:
The digital sensor supply voltage is 8.0 ± 0.5 VDC.
Results:
- OK - The supply voltage is reaching the sensor. Proceed to Test Step 5.
- Not OK - The supply voltage is not reaching the sensor. Proceed to Test Step 7.
Test Step 5. Check the Digital Sensor for an Internal Short
- Install a 7X-6370 Adapter Cable As (3 Pin DT Breakout) at the sensor connector, but do not connect the sensor to the breakout at this time.
- Turn the keyswitch to the ON position.
- Reconnect the throttle position sensor while you observe the voltage across terminals A (+8 VDC) and B (Return) at the breakout.
Expected Result:
The supply voltage is 8.0 ± 0.5 VDC and the voltage does not drop when the sensor is connected.
Results:
- OK - The sensor does not have an internal short.
Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent.
STOP
- Not OK - The sensor may have an internal short. Proceed to Test Step 6.
Test Step 6. Temporarily Install a New Sensor
- Disconnect the suspect sensor and remove the suspect sensor.
- Turn the keyswitch to the ON position.
- Temporarily connect a new sensor to the breakout while you observe the voltage across terminals A (+8 VDC) and B (Return) at the breakout.
Expected Result:
The supply voltage is 8.0 ± 0.5 VDC and the voltage does not drop when the sensor is connected.
Results:
- OK - The suspect sensor was faulty.
Repair: Permanently install the new sensor.
STOP
- Not OK - The sensor and the circuit appear to be OK at this time.
Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent.
STOP
Test Step 7. Check the Digital Sensor Supply Voltage at the ECM
- Install a 140-2266 Cable (Seventy-Pin Breakout) at the J1/P1 ECM connector.
- Turn the keyswitch to the ON position.
- Measure the voltage across P1:4 (+8 VDC) and P1:5 (Return) at the breakout.
Expected Result:
The supply voltage is 8.0 ± 0.5 VDC.
Results:
- OK - The ECM is supplying the correct voltage.
Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent.
STOP
- Not OK - The ECM is not supplying the correct voltage.
Repair: Verify your results.Replace the ECM. Refer to Troubleshooting, "Replacing the ECM" before replacing the ECM.Verify that the repair eliminates the problem.
STOP