SCREW-OVAL HEAD 3E9874 - Caterpillar

replace any wiring that failed the resistance check.
Use the electronic service tool to perform the "Glow Plug Start Aid Override Test".
Confirm that the fault has been eliminated.STOPTest Step 8. Check the ECM
Make sure that the latest flash file for the application is installed in the ECM. Refer to Troubleshooting, "Flash Programming".
Contact the Technical Communicator at a Cat dealer.Note: This consultation can greatly reduce the repair time.
If the Technical Communicator recommends the use of a test ECM, install a test ECM. Refer to Troubleshooting, "Replacing the ECM".
Use the electronic service tool in order to clear all logged diagnostic codes.
Use the electronic service tool in order to perform a "Glow Plug Start Aid Override Test".Results:
OK - The replacement ECM functions correctly. Performing the "Glow Plug Start Aid Override Test" energizes the glow plugs.Repair: Perform the following procedure:
Reconnect the suspect ECM.
If the fault returns with the suspect ECM, replace the ECM.
Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.STOP
Not OK - The fault is still present with the replacement ECM. Do not use the replacement ECM.Repair: Contact the Technical Communicator at a Cat dealerSTOPTest Step 9. Test the Continuity of the Glow Plugs
Disconnect the power supply and remove the bus bar from the glow plugs.
Use a suitable digital multimeter to check continuity (resistance). Turn the audible signal on the digital multimeter ON.
Place one probe on the connection for one of the glow plugs and the other probe to a suitable ground. The digital multimeter should make an audible sound.
Repeat the continuity check on the remaining glow plugs.Expected Result:One or more glow plugs do not have continuity.Results:
OK - All glow plugs display continuity. Repeat this procedure from Test Step 1.
Not OK - One or more of the glow plugs do not display continuity.Repair: Perform the following procedure:
Replace any glow plugs that do not display continuity.
Confirm that the fault has been eliminated.STOPTest Step 10. Check the Relay Coil for an Open Circuit
Turn the keyswitch to the OFF position.
Measure the resistance from Test Point 1 to Test Point 2 on the harness connector for the glow plug start aid relay.
Switch the probes of the ohmmeter and measure the resistance from Test Point 2 to Test Point 1 on the harness connector for the relay.Expected Result:Both resistance measurements should be less than 10,000 Ohms.Results:
OK - Both resistance measurements are less than 10,000 Ohms. Reconnect the glow plug start aid relay. Proceed to Test Step 11.
Not OK - One of the resistance measurements was more than 10,000 Ohms. The fault is in the relay coil.Repair: Perform the following repair:
Install a replacement relay.
Use the electronic service tool to perform the "Glow Plug Start Aid Override Test".
Confirm that the fault has been eliminated.STOPTest Step 11. Check the Fuse
Turn the battery disconnect switch to the OFF position.
Check the fuse for the glow plug start aid relay. Refer to Illustration 1.Results:
The fuse is blown. - There is a short in the power circuit for the glow plugs.