COMPRESSOR GP-REFRIGERANT 3729360 - Caterpillar

Illustration 3 g00725363
Breakout T
Ensure that the ET is connected to the cab data link connector.
Disconnect machine harness connector P1 from ECM connector J1 and insert a 70-Terminal Breakout T.
Turn the keyswitch to the ON position.
Measure the voltage between machine harness connector P1 terminal 48 (UNSWITCHED +BATTERY) and terminal 61 (− BATTERY). Also measure the voltage between terminal 52 (UNSWITCHED +BATTERY) and terminal 63 (− BATTERY).
Measure the voltage between machine harness connector P1 terminal 70 (keyswitch) and terminal 63 (− BATTERY).Refer to Illustration 3.Expected Result:The voltage is between 22.0 VDC and 27 VDC when the keyswitch is in the ON position.Results:
Yes - The ECM is currently receiving the correct voltage. Proceed to Test Step 5.
No - The ECM is not receiving the correct voltage. Repair: Perform the following diagnostic procedure:Troubleshooting, "Electrical Power Supply Circuit - Test"STOPTest Step 4. Check the Battery Voltage that Is Coming to the Cab Data Link Connector.
Illustration 4 g00725289
Data Link connector
Turn the keyswitch to the ON position.
Use a multimeter in order to measure the voltage from the + BATTERY terminal of the cab data link connector to the − BATTERY terminal of the cab data link connector.Refer to Illustration 4.Expected Result:The voltage is between 22.0 VDC and 27.0 VDC.Results:
Yes - The cab data link connector is currently receiving the correct voltage. Proceed to Test Step 6.
No - The cab data link connector is not receiving the correct voltage.Repair: Inspect the wiring and fuses to the connector. Repair the wiring or batteries and/or replace the wiring or batteries, as required. Send the machine to the OEM dealer for repair, if necessary. Verify that the repair eliminates the problem.STOPTest Step 5. Connect the Electronic Service Tool Directly to the ECM.
Illustration 5 g00724036
Bypass harness
Batteries give off flammable fumes which can explode.To avoid injury or death, do not strike a match, cause a spark, or smoke in the vicinity of a battery.
Do Not connect the Bypass Harness to the battery until the 20 Amp in-line fuse has been removed from the +Battery line. If the fuse is not removed before connection to the battery a spark may result.
Turn the keyswitch to the ON position.
Disconnect machine harness connector J1/P1 from the ECM.
Construct a bypass harness for the ET. Connect the bypass harness to ECM machine harness connector J1.Refer to Illustration 5 for the bypass harness.Note: This bypass directly connects the circuit for the keyswitch to the ECM. The ECM will remain powered until the connection to the unswitched battery line "+" is disconnected. Remove the 20 Amp fuse from the in-line fuse holder to power down the ECM. Do Not connect the bypass to the battery posts without first removing the 20 Amp in-line fuse or do not remove the bypass from the battery posts without first removing the 20 Amp in-line fuse.Expected Result:The ET is operating correctly.Results:
Yes - Repair: Perform the following repair:There is a problem in the machine wiring, or another device in the machine is causing problems on the data link. Reinsert the two data link lines into ECM machine