DISC 7T5359 - Caterpillar

Illustration 1 g02061279
Power terminals at the service tool connector (Terminal A) +Battery (Terminal B) -Battery
Table 2
Troubleshooting Test Steps    Values    Results    
5. Check the Electrical Power to the Communication Adapter
A. Check for battery voltage at the service tool connector.     Electrical Power     Result: 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.
Result: Cat ET indicates that the engine is serviced on both links.
Repair: Verify that the cable between the service tool connector and the communication adapter is OK. Replace the cable, if necessary.
Repair: Replace the communication adapter if the following conditions are true:
1. There is power at the cables "DATA LINK" connector.
2. The communication adapters "POWER" indicator is not illuminated.    
Illustration 2 g02061196
General information about the electrical power to the ECM
Table 3
Troubleshooting Test Steps    Values    Results    
6. Check the Electrical Power to the ECM
A. Verify that the keyswitch is ON.
B. 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.
C. Verify that battery voltage is present at P1-70.
    Electrical Power     Result: 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.
Result: Battery voltage is present at all of the appropriate P1 terminals.
Proceed to the Test Step 7    
6. Try to Establish Communication With a Bypass Harness
A. 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.
B. Attempt to establish communication.     Harness     Result: 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".