COVER 4J0975 - Caterpillar

Illustration 1 g01118624
Part of the Schematic of the Cat Data Link
This diagnostic code is recorded when the Power Train ECM cannot communicate with the Engine ECM via the Cat Data Link. The update rate from the ECM is not correct.The Cat Data Link is an input and an output of all modules. The Cat Data Link is designed to enable communications for all electronic control modules and service tools. The Cat Data Link is not a visible component. The data link consists of internal control circuits and the connecting harness wiring.Test Step 1. CHECK THE COMPATIBILITY OF THE SOFTWARE.
Verify that the software is compatible. For the correct software part numbers, refer to the Electronics Groups in the parts manual for the machine that is being serviced . Expected Result:The software is compatible.Results:
OK - The software is compatible. Proceed to test step 2.
NOT OK - The software is NOT compatible.Repair: Install the correct software. Ensure that the correct part number was used if any electronic control modules have been replaced. Continue if the conditions are not resolved. STOPTest Step 2. CHECK THE +BATTERY CIRCUIT.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect connector J1 from the ECM.
Turn the disconnect switch and the key start switch to the ON position.
At connector J1, measure the voltage from +battery terminals to the negative battery terminals. Expected Result:The voltage should measure 18 to 35 DCV.Results:
OK - The voltage is correct. The ECM is receiving the voltage. Proceed to test step 3.
NOT OK - The voltage does NOT measure 18 to 35 DCV.Repair: The ECM is NOT receiving the correct voltage. Ensure that proper ground is available. If the ground is correct, repair the power circuit. Also, check the circuit breakers.If conditions are not resolved proceed to test step 3.Test Step 3. CHECK THE DATA LINK CIRCUIT FOR