This fault is recorded when the all wheel drive ECM does not receive a signal from the engine speed sensor, and other conditions indicate that an engine speed signal should exist. The engine speed sensor is located on the flywheel housing for the engine. This fault is caused by the following conditions.
- There is a bad connection to the frame or wire 202-BK is open.
- The engine speed sensor needs to be cleaned or adjusted.
- The engine speed sensor is faulty.
- The harness for the all wheel drive ECM has a short or the harness for the all wheel drive ECM has an open.
Reference: Refer to Troubleshooting, "Engine Speed Sensor".Schematic...
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| Illustration 1 | g00549219 |
ENGINE SPEED SENSOR GRAPHIC | |
System Response:
The fault should not be active when the machine is stopped and the engine has been shut off. When this fault is active and the all wheel drive system is ON (AUTOMATIC), the all wheel drive ECM will enter the diagnostic operating mode. The all wheel drive system will shut off and a category three warning will be activated.
Test Step 1. Perform the following test: Machine Preparation for Troubleshooting
Results:
- OK - Proceed to test step 2.
Test Step 2.
- Turn the key start switch to the OFF position. Disconnect the machine harness from the engine speed sensor.
- Use a 6V-7070 Digital Multimeter in order to measure the resistance at the machine harness. Measure the resistance from contact 1 (Wire 202-BK) to the frame ground. The resistance should be less than 2 ohms.
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| Illustration 2 | g00549219 |
ENGINE SPEED SENSOR GRAPHIC | |
Expected Result:
The resistance is less than 2 ohms.
Results:
- Yes - Proceed to test step 3.
- No - Proceed to test step 4.
Test Step 3.
- Turn the key start switch to the OFF position. Remove the engine speed sensor from the flywheel housing on the engine. Check the engine speed sensor for any debris on the sensor tip.
- Clean any debris off the tip of the engine speed sensor. Install the sensor to the flywheel housing. Adjust the engine speed sensor to the correct depth.
- Turn the key start switch to the ON position. Put the all wheel drive ECM in the service mode. Clear all of the inactive faults from the all wheel drive ECM. Start the engine and operate the engine at high idle. Operate the all wheel drive system.
- Stop the machine and shut off the engine. Check the all wheel drive ECM for the 190-02 fault.
Reference: Refer to Troubleshooting, "Engine Speed Sensor Adjustment".
Expected Result:
The 190-02 fault is present and active.
Results:
- Yes - Proceed to test step 5.
- No - Stop.
Test Step 4.
- Repair the faulty harness or replace the faulty harness. Use new Caterpillar parts for replacement.
Expected Result:
The harness has been repaired or the harness has been replaced.
Results:
- Repair Complete - Stop.
Test Step 5.
- Turn the key start switch to the OFF position. Disconnect the machine harness from the engine speed sensor.
- Use a 6V-7070 Digital Multimeter in order to measure the resistance at the machine harness. Measure the resistance between the two contacts. The resistance should be between 100 and 500 ohms.
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| Illustration 3 | g00549219 |
ENGINE SPEED SENSOR GRAPHIC | |
Expected Result:
The resistance is between 100 and 500 ohms.
Results:
- No - Proceed to test step 6.
- Yes - Proceed to test step 7.
Test Step 6.
- Turn the key start switch to the OFF position. Remove the engine speed sensor from the flywheel housing on the engine.
- Use a new Caterpillar part for replacement. Install a new engine speed sensor to the flywheel housing. Adjust the engine speed sensor in order to obtain the correct air gap.
- Clear the 190-02 fault from the all wheel drive ECM. Resume normal machine operation.
Reference: Refer to Troubleshooting, "Engine Speed Sensor Adjustment".Parts
Reference: Refer to Troubleshooting, "7W-3355 MAGNETIC PICKUP GP PIN 5AK1-UP. PART OF 8X-7719 WIRING GP-ENGINE".Schematic...
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| Illustration 4 | g00549219 |
ENGINE SPEED SENSOR GRAPHIC | |
Expected Result:
The engine speed sensor has been replaced and the engine speed sensor has been correctly adjusted.
Results:
- Repair Complete - Stop.
Test Step 7.
- Clean the contacts on the machine harness. Connect the machine harness to the engine speed sensor. Disconnect the harness at the all wheel drive ECM.
- Use a 6V-7070 Digital Multimeter in order to measure the resistance at the harness for the all wheel drive ECM. Measure the resistance between contact 2 (ground) and contact 6 (wire 450-YL). The resistance should be between 100 and 500 ohms.
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| Illustration 5 | g00550731 |
ECM | |
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| Illustration 6 | g00549219 |
ENGINE SPEED SENSOR GRAPHIC | |
Expected Result:
The resistance is between 100 and 500 ohms.
Results:
- No - Proceed to test step 8.
- Yes - Proceed to test step 9.
Test Step 8.
- Repair the faulty harness or replace the faulty harness. Use new Caterpillar parts for replacement.
Expected Result:
The harness has been repaired or the harness has been replaced.
Results:
- Repair Complete - Stop.
Test Step 9.
- Clean the contacts on the harness for the all wheel drive ECM.
- Connect the harness for the all wheel drive ECM to the all wheel drive ECM.
- Turn the key start switch to the ON position. Put the all wheel drive ECM in the service mode. Clear all the inactive faults from the all wheel drive ECM.
- Start the machine and operate the machine in high idle. Turn the all wheel drive control to the ON (AUTOMATIC or MANUAL) position. Operate the all wheel drive system.
- Stop the machine and shut off the engine. Check the all wheel drive ECM for the 190-02 fault code.
Reference: Refer to Troubleshooting, "Using The ECM Display For Troubleshooting".
Expected Result:
The 190-02 fault code is present.
Results:
- Yes - Proceed to test step 10.
- No - The fault does not exist at this time. The initial fault was probably caused by a poor electrical connection at one of the harness connectors. Resume normal machine operation. Stop.
Test Step 10. Perform the following test: All Wheel Drive Electronic Control - Test
Results:
- OK - Stop.
- REPAIRED, OK - Stop.