994H Large Wheel Loader VIMSTM 3G / Product Link Caterpillar

The following can cause power to an ECM to fail:

• Open circuit

• Poor connection

• Failed fuse or tripped circuit breaker

A short or overloaded circuit can cause a fuse to fail or a circuit breaker to trip.

Test Step 1. CHECK THE ECM FOR POWER AND GROUND

On the VIMS^TM 3G Main ECM, measure the voltage from contact 52 (wire 170-RD) to contact 65 (wire 251-BK).

Expected Result:

The measured voltage is the same as system voltage.

Results:

• OK - The measured voltage is the same as system voltage. STOP

• NOT OK - The measured voltage is low or non-existent. Proceed to Test Step 2.

Test Step 2. CHECK THE FUSE OR CIRCUIT BREAKER

1. Check the ECM power supply fuse or circuit breaker.

   The ECM fuse wire is 170-RD.

Expected Result:

The fuse is good or the circuit breaker has not tripped.

Results:

• OK - The fuse is good or the circuit breaker has not tripped. Proceed to Test Step 3.

• NOT OK - The fuse has failed or the circuit breaker has tripped.

  Repair: Replace the fuse or reset the circuit breaker.Monitor the machine for a recurrence of the problem. If the problem persists, the reason for the problem must be corrected.

  STOP

Test Step 3. CHECK THE ECM POWER WIRE

1. Turn off the keyswitch and the disconnect switch.

2. Measure the resistance of VIMS 3G ECM wire 170-RD at the fuse or circuit breaker and contact 52 of the VIMS 3G Main ECM connector.

Expected Result:

The resistance is low.

Results:

• OK - The resistance is low. Proceed to Test Step 4.

• NOT OK - The resistance is high. The circuit is open.

  Repair: Repair or replace the harness.

  STOP

Test Step 4. CHECK THE ECM GROUND CONNECTIONS

1. The keyswitch and the disconnect switch remain off.

2. Measure the resistance between contact 65 251-BK at the VIMS 3G Main ECM connector and frame ground.

Expected Result:

The resistance is low.

Results:

• OK - The resistance is low. The ECM may have failed, however, ECM failure is unlikely.

  Repair: Perform this procedure again. If the problem remains, contact your Cat dealer. If ECM replacement is necessary, see Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP

• NOT OK - The resistance is high.

  Repair: Repair or replace the harness.

  STOP