GUARD-SWITCH 2495492 - Caterpillar

Illustration 1 g01430920
Power terminals at the service tool connector (Terminal A) +Battery (Terminal B) −BatteryCheck for battery voltage at the service tool connector. Refer to Illustration 1.Expected Result:Battery voltage is present at the service tool connector.Results:
OK - 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 harness connector for the communication adapter.
The communication adapter's "POWER" indicator is not illuminated.STOP
Battery voltage is not present at the service tool connector. - Repair: Inspect the application's 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 will not communicate on both data links.Test Step 6. Check the Electrical Power to the ECM
Verify that electrical power for the application is turned on.
Illustration 2 g01640382
Terminal locations at the J1/P1 ECM connectors for the ECM power supply circuit (typical wiring) (48) Unswitched +Battery (52) Unswitched +Battery (53) Unswitched +Battery (61) −Battery (63) −Battery (65) −Battery (70) Keyswitch
Illustration 3 g01640386
Schematic for the ECM power supply circuit (typical wiring diagram)
Refer to Illustrations 2 and 3. Verify that battery voltage is present at the terminals that are indicated in the Illustration. Be sure to connect the voltmeter between the +Battery terminals and the −Battery terminals at the ECM connector.
Verify that battery voltage is present at P1-70 when the keyswitch is turned on.Expected Result:Battery voltage is present at all of the P1 terminals that are associated with the ECM power supply circuit.Results:
OK - Battery voltage is present at all of the appropriate P1 terminals. The circuits for the battery power to the ECM are OK. Proceed to the Test Step 7.
Not OK - Battery voltage is not present at an ECM battery connection.Repair: Inspect the application's wiring, fuses, and/or circuit breakers. Determine the cause of the missing voltage. Make the necessary repairs.Attempt to establish communication after the electrical problem at the ECM has been resolved. Continue with this procedure, if necessary.STOPTest Step 7. Try to Establish Communication with a Bypass Harness
Connect the communication adapter to the engine ECM with a 167-9225 Harness (SERVICE TOOL ADAPTER). This harness supports communication on both data links.
Attempt to establish communication.Expected Result:Cat ET communicates on both data links when the bypass harness is used.Results:
OK - Cat ET communicates on both data links when the bypass harness is used. There is a problem with the application's wiring for one of the data links.Repair: Repair the data link. Refer to Troubleshooting, "Data Link - Test".STOP