GEAR (59 TEETH) 7N3942 - Caterpillar

Illustration 1 g02061279
Power terminals at the service tool connector (Terminal A) +Battery (Terminal B) -Battery
Check for battery voltage at the service tool connector.Results:
Battery voltage is not present at the service tool connector. - Repair: Inspect the vehicles wiring and fuses. Determine the cause of the missing voltage. Make the necessary repairs. Attempt to establish communication after the electrical power is at the service tool connector. Proceed to Test Step 6 if the service tool does not communicate on both data links.
Battery voltage is present at the service tool connector. - Repair: Verify that the cable between the service tool connector and the communication adapter is OK. Replace the cable, if necessary.Replace the communication adapter if the following conditions are true:
There is power at the cables "DATA LINK" connector.
The communication adapters "POWER" indicator is not illuminated.STOPTest Step 6. Check the Electrical Power to the ECM
Verify that the keyswitch is ON.
Illustration 2 g02061196
General information about the electrical power to the ECM
Refer to Illustration 2. Verify that battery voltage is present at the terminals that are indicated in the Illustration. Be sure to connect the voltmeter between the "UNSWITCHED +BATTERY" terminals and the "-BATTERY" terminals.
Verify that battery voltage is present at P1-70.Results:
Yes - Battery voltage is missing from a P1 terminal.Repair: Inspect the vehicles wiring and fuses. Determine the cause of the missing voltage. Make the necessary repairs.Attempt to establish communication after the electrical power is at all of the appropriate P1 terminals. Continue with this procedure, if necessary.STOP
No - Battery voltage is present at all of the appropriate P1 terminals. Proceed to the Test Step 7.Test Step 7. Try to Establish Communication With a Bypass Harness
Connect the communication adapter to the engine ECM with a 217-0113 Wiring Harness (ECM BYPASS) and a 328-2292 Harness (ELECTRONIC CONTROL MODULE). The harnesses support communication on both data links.
Attempt to establish communication.Results:
Yes - Cat ET communicates on both data links when the bypass harness is used. There is a problem with the wiring.Repair: Repair the data link. Refer to Troubleshooting, "Data Link - Test".STOP
- Repair: For additional troubleshooting information, select the "Help" tab located on the tool bar in CAT Electronic Technician, then select the "Troubleshooting" tab.STOP