LINK-MASTER 6Y0940 - Caterpillar

Table 2
Points to Check for Continuity    
Connector and Terminal     Connector and Terminal    
P1-59     Terminal 18 at the harness connector for the actuator    
P1-60     Terminal 10 at the harness connector for the valve    
P1-59     ECM ground strap    Expected Result:Both of the wires have continuity. Terminal P1-59 is not shorted to ground.Results:
OK - All of the measurements are within the specifications. The wiring appears to be OK.Repair: Perform the following procedure:
Connect the J1/P1 ECM connectors. Connect the harness connector for the compressor bypass actuator.
Restore the electrical power to the engine. Start the engine and run the engine. Check for an active 1720-8 code.If the code does not recur, the problem appears to be resolved. The original problem was probably caused by a poor electrical connection. Refer to Troubleshooting, "Electrical Connectors - Inspect" for information that is related to troubleshooting intermittent electrical problems.
If the 1720-8 code remains active, there may be a problem with the ECM or with the compressor bypass actuator. Perform the following procedure:
Temporarily install a new ECM. Refer to Troubleshooting, "ECM - Replace". If the problem is resolved with the new ECM, install the original ECM and verify that the problem returns. If the new ECM operates correctly and the original ECM does not operate correctly, replace the original ECM. Refer to Troubleshooting, "ECM - Replace". If the problem is not resolved with a new ECM, install the original ECM. Continue with this procedure.
Temporarily install a new compressor bypass actuator. If the new actuator operates correctly, the problem is resolved. If the new actuator does not operate correctly, install the original actuator. Retest the system.STOP
Not OK - At least one of the measurements is incorrect.Repair: There is a problem with the wiring between the ECM and the compressor bypass actuator. Repair the connector and/or the wire, when possible. Replace parts, if necessary.STOPTest Step 4. Check for Electrical Power at the Actuator
Restore the electrical power to the engine. Set the engine control switch to the STOP position.
Refer to Illustration 2. Measure the voltage for the actuator at the engine junction box.
Disconnect the harness connector from the actuator.
Measure the voltage between terminals 1 and 16 at the harness connector for the actuator.
Measure the voltage between terminals 5 and 16 at the harness connector for the actuator.
Set the engine control switch to the OFF/RESET position. Remove the electrical power from the engine.
Restore the wiring to the original configuration.Expected Result:The voltage at the harness connector for the actuator is 18 v to 32 v.Results:
OK - The voltage at the harness connector is 18 v to 32 v.Repair: The actuator is receiving the proper operating voltage. Perform the following procedure:
Confirm that the 1720-9 diagnostic code is still active.Note: Monitor the active diagnostic code and the logged diagnostic codes on Cat ET. Wait at least 30 seconds in order for diagnostic codes to become active.If the 1720-9 code is still active, there is a problem in the circuit for the CAN data link. Refer