797 and 797B Off-Highway Truck Power Train Electronic Control System Caterpillar

Illustration 1	g00582008
Schematic Of The Machine Lockout Indicator Lamp

Test Step 1. CHECK THE INDICATOR LAMP.

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

2. Replace the indicator lamp with a similar indicator lamp that is known to be correct.

3. Turn the disconnect switch and the key start switch to the ON position.

4. Observe the indicator lamp.

Results:

• OK - The indicator lamp functions properly during the three second test cycle.

  STOP

• NOT OK - The indicator lamp is not the problem. Proceed to Test Step 2.

Test Step 2. CHECK THE HARNESS.

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

2. Disconnect the machine harness from the transmission ECM.

3. Turn the disconnect switch and the key start switch to the ON position.

4. At the machine harness connector for the transmission ECM, measure the voltage between connector J2-1 wire (126-AM22-RD(Red)) and frame ground. The voltage must be above 20.5 VDC in order to illuminate the indicator lamp.

5. Turn the key start switch and the disconnect switch to the OFF position.

6. Install a jumper wire from connector J2-1 wire (126-AM22-RD(Red)) to connector J2-55 wire (H453-AM16-GY(Grey)).

7. At the machine harness connector for the transmission ECM, connect J2-36 wire (H807-AM13-YL(Yellow)) to frame ground.

8. Turn the disconnect switch and the key start switch to the ON position.

Expected Result:

The indicator lamp illuminates.

Results:

• OK - The indicator lamp illuminates. The harness circuit is functioning correctly. The ECM may have failed.

  Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. The problem is active or the problem is NOT active. Replace the ECM if the problem is not found. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP

• NOT OK - There is an open in the harness. Proceed to Test Step 3.

Test Step 3. CHECK THE HARNESS.

1. Remove wire (H453-AM16-GY(Grey)) from the socket of the indicator lamp.

2. Check for an open circuit between the following points. Check between the circuit of the indicator lamp (wire H453-AM16-GY(Grey)) and J2-55.

3. Check for an open circuit between the following points. Check between the circuit of the indicator lamp (wire H807-AM13-YL(Yellow)) and contact J2-36.

Expected Result:

The circuits are correct.

Results:

• OK - The circuits are correct.

  STOP

• NOT OK - The circuits are NOT correct. Repair the harness or replace the harness.

  STOP