143H and 163H Motor Graders All Wheel Drive Caterpillar

This fault is recorded when the all wheel drive ECM receives three open signals from the all wheel drive switch. Normally, two of the signals are open and one signal is connected to ground. This fault is caused by the following conditions.

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

• The all wheel drive switch is faulty.

• The machine harness is faulty.

Reference: Refer to Troubleshooting, "AWD Mode Switch".

System Response:

This fault can be active when the key start switch is turned ON. When this fault is active and the all wheel drive system is ON (AUTOMATIC or MANUAL), 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.

1. Turn the key start switch to the OFF position. Disconnect the machine harness from the all wheel drive switch.

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

Illustration 1	g00545894
AWD SWITCH 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.

1. Leave the key start switch in the OFF position. Leave the machine harness disconnected from the all wheel drive switch.

2. Use a 6V-7070 Digital Multimeter in order to check for an open circuit at all of the positions for the all wheel drive switch. An open circuit should not exist in the all wheel drive switch.

Illustration 2	g00545894
AWD SWITCH GRAPHIC

Expected Result:

An open circuit does NOT exist in the all wheel drive switch.

Results:

• No - Proceed to test step 5.

• Yes - 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. Replace the all wheel drive switch. Use a new Caterpillar part for replacement.

Reference: Refer to Troubleshooting, "8X-7721 WIRING GP-SHIFT CONSOLE PIN 5AK156-UP. PART OF 8W-6320 CHASSIS AR".Schematic...

Illustration 3	g00545894
AWD SWITCH GRAPHIC

Expected Result:

The all wheel drive switch has been replaced.

Results:

• Repair Complete - Stop.

Test Step 6.

1. With the key start switch in the OFF position, disconnect the harness from the all wheel drive ECM.

2. At the machine harness for the all wheel drive switch, place a jumper between contact 4 (wire 823-GN) and the frame ground. Use a 6V-7070 Digital Multimeter in order to check the resistance between contact 23 (wire 823-GN) and contact 2 (wire 202-BK) on the all wheel drive ECM harness. The resistance should be less than 5000 ohms.

3. At the machine harness for the all wheel drive switch, place a jumper between contact 6 (wire 718-BU) and the frame ground. Use a 6V-7070 Digital Multimeter in order to check the resistance between contact 24 (wire 718-BU) and contact 2 (wire 202-BK) on the all wheel drive ECM harness. The resistance should be less than 5000 ohms.

4. At the machine harness for the all wheel drive switch, place a jumper between contact 1 (wire 719-GY) and the frame ground. Use a 6V-7070 Digital Multimeter in order to check the resistance between contact 25 (wire 719-GY) and contact 2 (wire 202-BK) on the all wheel drive ECM harness. The resistance should be less than 5000 ohms.

5. Remove the jumpers from the contacts.

Illustration 4	g00545894
AWD SWITCH GRAPHIC

Illustration 5	g00550731
ECM

Expected Result:

The resistance is less than 5000 ohms.

Results:

• Yes - Proceed to test step 7.

• No - Proceed to test step 4.

Test Step 7.

1. Clean the contacts on the harness for the all wheel drive ECM and clean the contacts on the machine harness. Connect the harness to the all wheel drive ECM. Connect the machine harness to the all wheel drive switch.

2. 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.

3. Check the all wheel drive ECM for the 517-03 fault code.

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

Expected Result:

The 517-03 fault code is present.

Results:

• Yes - Proceed to test step 8.

• 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 8. Perform the following test: All Wheel Drive Electronic Control - Test

Results:

• OK - Stop.

• REPAIRED, OK - Stop.