C2.4 Tier 4 Final Engines for Caterpillar Built Machines Caterpillar

Electrical Power Supply - Test

Usage:

If the engine ECM loses power, the engine will not start or will stop running. This will be evident since Caterpillar^® Electronic Technician (Cat ET) will not be able to establish communication with the engine ECM.

Probable Causes

• Codes
• Battery
• Battery cables
• Machine starting circuit
• Starter

Recommended Actions

Show/hide table

Table 1
Troubleshooting Test Steps	Values	Results
1. Check for Active and Logged Codes A. Establish communication between Cat ® Electronic Technician (ET) and the Electronic Control Module (ECM). B. Download the “Product Status Report” from the engine ECM before troubleshooting or clearing any diagnostic codes.	Codes	Result: Cat ET cannot connect to the engine ECM since the engine ECM is not turned on. Refer to Systems Operation, Electrical System - Starting System Circuit to resolve the machine's starting circuit issue that is not providing power to the Engine ECM. Proceed to Test Step 2. Result:There are diagnostic codes active or logged. Repair: Troubleshoot any code that is active or logged before continuing with the troubleshooting procedure. If the problem is not resolved, proceed to Test Step 2.
2. Inspect the Batteries and Battery Cables A. Inspect the main power switch, battery posts, and battery cables for loose connections and corrosion. If the battery cables are corroded, remove and clean the battery cables. Tighten any loose connections that are found. B. Check the resistance of the Battery+ cable that runs to the starter. If the resistance is less than 1Ω, the cable is OK. C. Inspect the batteries, refer to Battery - Test.	Batteries and cables	Result: The batteries and cables are OK. Proceed to Test Step 3. Result: The batteries and cables are NOT OK. Repair:Make the necessary repairs. If the problem is not resolved, proceed to Test Step 3.
3. Check the Machine Starting Circuit A. Check the starter relay for proper operation. Refer to the System Operations, Electrical System - Starter Operation for details on how the starter relay receives ground from the engine ECM. Refer to the machine Electrical Schematic for how the start relay receives 12 V from the machine ECM.	Machine starting circuit	Result:The starter relay is OK. Proceed to Test Step 4. Result:The starter relay is NOT OK. Repair: Refer to the machine Electrical Schematic to troubleshoot the circuit. If the problem is not resolved, proceed to Test Step 4.
4. Check the Starter for Proper Operation A. Check the starter post from the battery for 12 V supply. B. Check the starter for a good ground. C. Check that the starter solenoid from the relay is 12 V during the cranking cycle. Note: For the Skid Steer Loaders, Multi-Terrain Loaders, and Compact Track Loaders, the belt guard must be installed. Take necessary precautions to ensure that there is no contact with the belt.	Starter	Result:The results are NOT OK. Repair:Repeat Test Step 3. Result:The results are OK. Repair:Replace the starter.

If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).