143H and 163H Motor Graders All Wheel Drive Caterpillar

This fault is recorded when the all wheel drive electronic control module (ECM) does not receive a signal from the ground speed sensor, and other conditions indicate that a ground speed signal should exist. This fault is caused by the following conditions.

• There is a bad ground connection to the frame or wire 202-BK is open.

• The supply circuit is faulty.

• There is a short in the machine harness between the positive battery circuit (wire 165-YL) and the signal circuit (wire C913-BU).

• There is a short in the machine harness between the ground circuit (wire 202-BK) and the signal circuit (wire C913-BU).

• There is an open in the signal circuit (wire C913-BU) for the machine harness.

Reference: Refer to Troubleshooting, "Ground Speed Sensor".Schematic...

Illustration 1	g00549493
GROUND SPEED SENSOR

System Response:

When this fault is active and the all wheel drive system is ON (AUTOMATIC), the all wheel drive electronic control module (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.

1. Turn the key start switch to the OFF position. Disconnect the machine harness from the ground speed sensor.

2. Use a 6V-7070 Digital Multimeter in order to measure the resistance at the machine harness. Measure the resistance from contact 2 (wire 202-BK) to the frame ground. The resistance should be less than 2 ohms.

Illustration 2	g00549493
GROUND SPEED SENSOR

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.

1. Turn the key start switch to the ON position.

2. Use a 6V-7070 Digital Multimeter in order to measure the voltage at the machine harness. Measure the voltage between contact 1 and contact 2. The voltage should be approximately 12 VDC.

Illustration 3	g00549493
GROUND SPEED SENSOR

Expected Result:

The voltage between contact 1 and contact 2 is 12 VDC.

Results:

• Yes - Proceed to test step 5.

• No - Proceed to test step 6.

Test Step 4.

1. 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.

1. Turn the key start switch to the OFF position.

2. Disconnect the machine harness from the all wheel drive ECM.

3. Use a 6V-7070 Digital Multimeter in order to measure the resistance at the machine harness. Measure the resistance between the contact 5 (signal) and the contact 1 (+battery). The resistance should be at least 5000 ohms.

Illustration 4	g00550731
ECM

Expected Result:

The resistance is at least 5000 ohms.

Results:

• Yes - Proceed to test step 7.

• No - Proceed to test step 4.

Test Step 6.

There is a problem in the 12 volt supply system. Check the system for possible faults. Continue to troubleshoot the electrical system.Schematic...

Illustration 5	g00546361
12V TO 24V CONVERTER GRAPHIC

Expected Result:

Results:

• OK - Stop.

Test Step 7.

1. Turn the key start switch to the OFF position.

2. Disconnect the machine harness from the all wheel drive ECM.

3. Use a 6V-7070 Digital Multimeter in order to measure the resistance at the machine harness. Measure the resistance between contact 5 (signal) and contact 2 (ground). The resistance should be at least 5000 ohms.

Illustration 6	g00550731
ECM

Expected Result:

The resistance is at least 5000 ohms.

Results:

• Yes - Proceed to test step 8.

• No - Proceed to test step 4.

Test Step 8.

1. Turn the key start switch to the OFF position.

2. Check the continuity of the signal wire (wire C913-BU).

3. Use a 6V-7070 Digital Multimeter in order to measure the resistance at the machine harness. Measure the resistance between contact 5 on the harness for the all wheel drive ECM and contact 2 on the machine harness. The resistance should be less than 5 ohms.

Illustration 7	g00549493
GROUND SPEED SENSOR

Expected Result:

The resistance is less than 5 ohms.

Results:

• No - Proceed to test step 4.

• Yes - Proceed to test step 9.

Test Step 9.

1. Clean the contacts on the machine harness. Clean the contacts on the harness for the all wheel drive ECM.

2. Connect the machine harness to the ground speed sensor. Connect the harness for the all wheel drive ECM to the all wheel drive ECM.

3. 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.

4. 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 machine in fourth speed forward through seventh speed forward. The engine speed must exceed 500 rpm.

5. Stop the machine and shut off the engine. Check the all wheel drive ECM for the 084-02 fault code.

Reference: Refer to Troubleshooting, "Using The ECM Display For Troubleshooting".

Expected Result:

The 084-02 fault code is present.

Results:

• 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.

• Yes - Proceed to test step 10.

Test Step 10.

1. Replace the ground speed sensor. Use new Caterpillar parts for replacement.

Reference: Refer to Troubleshooting, "Ground Speed Sensor".Parts

Reference: Refer to Troubleshooting, "132-4579 SENSOR GP-SPEED PIN 5AK1-UP. FIELD REPLACEMENT ORDER 7T-2633 FIELD INSTALLATION".Specifications

Reference: Refer to Troubleshooting, "Ground Speed Sensor".Schematic...

Illustration 8	g00549493
GROUND SPEED SENSOR

Expected Result:

The ground speed sensor has been replaced.

Results:

• Continue - Proceed to test step 11.

Test Step 11.

1. 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.

2. 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 machine in fourth speed forward through seventh speed forward. The engine speed must exceed 500 rpm.

3. Stop the machine and shut off the engine. Check the all wheel drive ECM for the 084-02 fault code.

Reference: Refer to Troubleshooting, "Using The ECM Display For Troubleshooting".

Expected Result:

The 084-02 fault code is present.

Results:

• No - Stop.

• Yes - Proceed to test step 12.

Test Step 12. Perform the following test: All Wheel Drive Electronic Control - Test

Results:

• REPAIRED, OK - Stop.

• OK - Stop.