COVER 1248822 - Caterpillar

The starting aid is used to improve the engine starting when the engine is cold. The engine ECM monitors the coolant temperature and the intake manifold air temperature in order to determine if the glow plugs are required. If the glow plugs are required, the ECM activates the starting aid relay for a controlled time. The starting aid relay supplies power to the glow plugs. If the optional "Wait to Start Lamp" is installed, the lamp will be illuminated during the "Wait To Start" period.On a cold start, a lamp output will indicate that the operator needs to "Wait to Start". Starting aids may be used during the cranking of the engine. Starting aids may be used if the engine has previously been started. The "Wait to Start" lamp will not be active in these conditions.The glow plug start aid override test switches on the cold starting aid when the engine is not running. The glow plug starting aid override test aids the analysis of the circuit for the starting aid relay.
Illustration 1 g01347322
Typical schematic for the starting aid switch
Illustration 2 g01347324
Typical view of the P1 ECM connector (1) Ground (GND) (2) Ground (GND) (3) Ground (GND) (9) Ground (GND) (10) Ground (GND) (57) Start aid controlTest Step 1. Inspect Electrical Connectors and Wiring
Remove the electrical power from the ECM.
Thoroughly inspect the P1 ECM connector. Inspect all of the terminal connections that are associated with the glow plug starting aid. Refer to service Troubleshooting, "Electrical Connectors - Inspect".
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.
Check the torque of the allen head screw on the ECM connectors. Refer to service Troubleshooting, "Electrical Connectors - Inspect".
Check the harness for abrasion and pinch points from the glow plugs back to the ECM.
Check that the fuses are not blown.Expected Result:All connectors, pins, and sockets are correctly coupled and inserted and the harness and wiring are free of corrosion, of abrasion, and of pinch points. The fuses are not blown.Results:
OK - The harness and the connectors are OK. The fuses are not blown. Proceed to Test Step 2.
Not OK - There is a problem with the connectors and/or wiring.Repair: Repair the connectors or the harness and/or replace the connectors or the harness. Ensure that all of the seals are correctly in place and ensure that the connectors are correctly coupled. If necessary, replace fuses.Verify that the repair has eliminated the problem.If applicable, use the electronic service tool to perform a "Wiggle Test".STOPTest Step 2. Check for Active Diagnostic Codes
Remove the electrical power from the ECM.
Connect the electronic service tool to the diagnostic connector.
Restore the electrical power to the ECM.
Use the electronic service tool to select the "Glow Plug Override Test".
Check for active diagnostic codes or recently logged diagnostic codes.Expected Result:One of the following diagnostic codes are active or recently logged:
2246-06 Glow Plug Start Aid Relay current above normal
2246-05 Glow Plug Start Aid Relay current below normalResults:
OK - The expected diagnostic