BOLT-SELF-LOCKING 8T0558 - Caterpillar

The Electronic Control Module (ECM) supplies a regulated voltage of 8.0 0.4 VDC to the throttle sensor.This procedure covers the following diagnostic codes:
041-03 8 Volt DC Supply short to +batt
041-04 8 Volt DC Supply short to groundA +8 V diagnostic code is probably caused by a short circuit to ground or a short circuit to another voltage source in the harness. The next likely cause is a problem with a sensor. The least likely cause is a problem with the ECM.
Illustration 1 g01220875
Schematic for the digital sensor supply
Test Step 1. Inspect the Electrical Connectors and the Wiring
Remove the electrical power from the ECM.
Illustration 2 g01140657
Typical left side view
(1) J1/P1 ECM connectors
Thoroughly inspect connector (1). Inspect the connectors for each digital sensor. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
Illustration 3 g01223008
P1 ECM connector
(P1-4) +8 VDC
(P1-5) Return
(P1-66) Throttle position sensor
(P!-32) Engine fan speed sensor
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the digital sensor supply.
Check the torque of the allen head screws for the ECM connectors. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
Check the harness and wiring for abrasions and for pinch points from the battery to the ECM. Expected Result:All of the connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring are free of corrosion, of abrasion or of pinch points.Results:
OK - The connectors and the wiring are OK. Proceed to Test Step 2.
Not OK - There is a problem with a connector and/or the wiring.Repair: Repair the connector and/or the wiring. Replace parts, if necessary. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled. Verify that the problem is resolved.STOPTest Step 2. Check for Active Diagnostic Codes
Connect the Caterpillar Electronic Technician (ET) to the service tool connector. Refer to electronic troubleshooting Troubleshooting, "Electronic Service Tools".
Restore the electrical power to the ECM.
Observe the active diagnostic code screen on Cat ET. Wait at least 30 seconds so that any codes may become active. Look for these codes:
041-03 8 Volt DC Supply short to +batt
041-04 8 Volt DC Supply short to groundExpected Result:One of the above diagnostic codes is active.Results:
Active 03 code - A 03 diagnostic code is active. Proceed to Test Step 3.
Active 04 code - A 04 diagnostic code is active. Proceed to Test Step 4.
No active codes - None of the above codes are active.Repair: If any of the above codes are logged and the engine is not running properly, refer to Troubleshooting, "Troubleshooting Without a Diagnostic Code".If the engine is running properly at this time, there may be an intermittent problem in a harness that is causing the codes to be logged. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".STOPTest Step 3. Check the Voltage on the +8 V Supply Wire
Remove the electrical power from the ECM.
Disconnect the harness connector for the throttle sensor.
Restore the electrical power to the ECM.
Measure the voltage between terminals A