The engine speed sensor provides the engine speed information to the ECM. The sensor magnetically detects the teeth on the flywheel ring gear. The ECM will not allow the engine to start until the ECM senses a valid engine speed signal.
Engine speed is determined by the frequency of the output signal. The signal frequency should be between 0 and 5 kHz.
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| Illustration 1 | g01637404 |
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| Illustration 2 | g01637405 |
(10) +8 VDC (18) Engine speed (35) Analog return | |
| Diagnostic Code | |||
|---|---|---|---|
| Code and Description | Flash Code | Default Conditions which Generate this Code | System Response |
| 190 -00 Engine Speed Sensor : High | 35 | The ECM detects a engine speed more than 2450 rpm. | The diagnostic code is logged. Also, the shutdown solenoid will de-energize until the engine speed is below 2420 rpm. |
| 190-02 Engine Speed Sensor : Erratic, Intermittent, or Incorrect | 34 | The ECM detects the loss of the primary engine speed signal. | The diagnostic code is active and logged. |
| 190-08 Engine Speed Sensor : Abnormal Frequency, Pulse Width, or Period | 33 | The engine speed is changing at a abnormal rate. | The diagnostic code is active and logged. |
| 190-10 Engine Speed Sensor : Abnormal Rate of Change | 34 | The engine speed is greater than 3000 rpm. This is due to noise or other conditions. | The diagnostic code is active and logged. Also, the shutdown solenoid will de-energize until the engine speed is below 2420 rpm. |
Test Step 1. Inspect Electrical Connectors and Wiring
- Turn the engine control switch to the OFF position.
- Thoroughly inspect the J14/P14 connector, and the J10/P10 connector. Refer to Troubleshooting, "Electrical Connectors - Inspect".
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the engine speed sensor.
- Check the allen head screw on each ECM connector for the proper torque. Refer to service Troubleshooting, "Electrical Connectors - Inspect".
- Check the harness for abrasions and for pinch points from the battery to the ECM.
Expected Result:
All connectors, pins, and sockets are completely coupled and/or inserted. 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. 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 in the connectors and/or wiring.
Repair: Repair the connectors or the harness and/or replace the connectors or the harness. Ensure that all of the seals are correctly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem.
STOP
Test Step 2. Check Engine Speed On Caterpillar Electronic Technician (ET)
- Connect Cat ET to the service tool connector.
- Turn the engine control switch to the ON position.
- Attempt to start the engine.
- Observe the engine speed on Cat ET.
- Turn the engine control switch to the OFF position.
Note: Battery voltage may drop below the required level during cranking. If the engine will not start, Cat ET may need to be powered by an outside source.
Expected Result:
Cat ET displayed a steady engine rpm.
Results:
- OK - Cat ET displays a steady engine rpm.
Repair: The engine speed sensor is functioning properly. For a intermittent problem, refer to Troubleshooting, "Electrical Connectors - Inspect".
STOP
- NOT OK - Cat ET does not display a steady engine rpm. Proceed to Test Step 3.
Test Step 3. Check The Sensor for a Short or for an Open
- Turn the engine control switch to the OFF position.
- Disconnect connector J10/P10.
- Measure the resistance between J10-B and J10-C.
Expected Result:
The resistance is between 500 ohms and 1500 ohms.
Results:
- OK - The resistance is between 500 ohms and 1500 ohms. Proceed to Test Step 4.
- NOT OK - The resistance is not between 500 ohms and 1500 ohms.
Repair: The sensor is faulty. Replace the sensor.
STOP
Test Step 4. Check for Shorts in the Harness
- Turn the engine control switch to the OFF position.
- Disconnect connector J10/P10 and connector J14/P14.
- Measure the resistance between P14-18 and P14-35.
- Measure the resistance between P14-18 and engine ground.
- Measure the resistance between P14-35 and engine ground.
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 5.
- NOT OK - The resistance is not greater than 20,000 ohms for each measurement.
Repair: There is a short in the harness. Repair the harness or replace the harness.
STOP
Test Step 5. Check the Resistance through the Harness
- Install Deutsch connectors on a 152 mm (6 inch) wire. This wire will be used to short the terminals of the engine speed sensor.
- Connect the wire betweenP10-C and P10-B.
- Measure the resistance between P14-18 and P14-35. Wiggle the harness during the measurement. This will reveal a intermittent problem.
Expected Result:
The resistance is less than 10 ohms.
Results:
- OK - The resistance is less than 10 ohms. Proceed to Test Step 6.
- NOT OK - The resistance is greater than 10 ohms.
Repair: The harness has a open. Repair the harness or replace the harness.
STOP
Test Step 6. Check the Engine rpm Signal at the Sensor
- Reconnect all connectors.
- Turn the engine control switch to the ON position.
- Measure the frequency between J10-C and J10-B. Use a 9U-7330 Digital Multimeter to measure the frequency. Take this measurement while the engine is cranking.
Expected Result:
The frequency is between 150 Hz and 1000 Hz while the engine is cranking. Also, the frequency is steady.
Results:
- OK - The frequency is between 150 Hz and 1000 Hz while the engine is cranking. Also, the frequency is steady. Proceed to Test Step 7.
- NOT OK - The frequency is not between 150 Hz and 1000 Hz while the engine is cranking. Also, the frequency is not steady.
Repair: The sensor is not producing the correct frequency. Replace the sensor.
STOP
Test Step 7. Check the Engine rpm Signal at the ECM
- Reconnect all connectors.
- Turn the engine control switch to the ON position.
- Measure the frequency between P14-18 and P14-35. Use a 9U-7330 Digital Multimeter to measure the frequency. This measurement should be taken while the engine is cranking.
Expected Result:
The frequency is between 150 Hz and 1000 Hz while the engine is cranking. Also, the frequency is steady.
Results:
- OK - The frequency is between 150 Hz and 1000 Hz while the engine is cranking. Also, the frequency is steady.
Repair: Verify if the problem still exists. Check the rpm on a electronic service tool. If the problem is not resolved, replace the ECM. Refer to Troubleshooting, "ECM - Replace" for more information.
STOP
- NOT OK - The frequency is not between 150 Hz and 1000 Hz while the engine is cranking. Also, the frequency is not steady.
Repair: The harness is faulty. Repair the harness or replace the harness.
STOP