The following procedure should be performed if the ECM does not turn on. Possible causes of failure are listed below:
- Blown fuse for the ECM
- Failure in the machine harness
Test Step 1. CHECK FOR A BLOWN FUSE
- Locate the fuse for the transmission ECM in the fuse panel of the machine.
- Check the condition of the fuse.
Expected Result:
The fuse is NOT blown.
Results:
- OK - The fuse is NOT blown. Proceed to test step 4.
- NOT OK - The fuse is blown. Proceed to test step 2.
Test Step 2. CHECK THE HARNESS
- Turn the ignition switch to the OFF position.
- Disconnect the machine harness from the ECM.
- Measure the resistance between contact 1 and contact 2 at the machine harness connector.
Expected Result:
The resistance is greater than 5000 ohms.
Results:
- OK - The resistance is greater than 5000 ohms. The wiring harness is correct. Proceed to test step 3.
- NOT OK - The resistance is less than 5 ohms. There is a short to ground in the +battery wire 126-PK for the control.
Repair: Repair the harness or replace the harness. Replace the blown fuse in the fuse panel of the machine.
Stop.
Test Step 3. CHECK THE ECM
- The machine harness connector remains disconnected from the ECM.
- Measure the resistance between contact 1 and contact 2 of the ECM.
Expected Result:
The resistance is approximately 5000 ohms.
Results:
- OK - The resistance is approximately 5000 ohms. The resistance is correct.
Repair: Replace the blown fuse in the fuse panel of the machine.
Stop.
- NOT OK - The resistance is NOT greater than 5000 ohms. The ECM has an internal short.
Repair: Replace the ECM. Refer to Testing and Adjusting, "Electronic Control Module - Replace". Replace the blown fuse in the fuse panel of the machine.
Stop.
Test Step 4. CHECK FOR BATTERY VOLTAGE AT THE ECM
- Turn the key start switch to the ON position.
- Measure the voltage at the battery terminals of the machine.
Note: Make a note of the voltage measurement.
- Use the 7X-1710 Multimeter Probe in order to measure the voltage at the harness connector between contacts 1 and 2.
Expected Result:
The voltage at the harness connector does NOT vary from the battery voltage by more than 0.5 VDC.
Results:
- OK - The voltage at the harness connector does NOT vary from the battery voltage by more than 0.5 VDC. The system voltage is correct.
Repair: Check the operation of the machine. If the machine is not functioning properly, proceed to Troubleshooting, "Using the Diagnostic Indicator to Determine Diagnostic Codes" and Troubleshooting, "Diagnostic Code List".
Stop.
- NOT OK - The voltage at the harness connector varies from the battery voltage by more than 0.5 VDC. The system voltage is NOT correct. A failure exists in the wiring from the ECM fuse to the ECM or a failure exists in the wiring from the ground stud to the ECM.
Repair: Repair the machine harness or replace the machine harness.
Stop.