WASHER 9R0158 - Caterpillar

System Operation Description:Use this procedure to troubleshoot any suspect problems with the +8 V digital supply.This procedure covers the following diagnostic codes:
41-03 8 Volt DC Supply short to +batt
41-04 8 Volt DC Supply short to groundThe Electronic Control Module (ECM) creates a regulated voltage of 8.0 0.4 VDC that is supplied to terminal A of the harness connector for the coolant level sensor.A +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 the sensor. The least likely cause is a problem with the ECM.
Illustration 1 g01094777
Schematic for digital supply
Test Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
Illustration 2 g01147202
Typical engine view
(1) J2/P2 connectors
Illustration 3 g01150138
Typical location of the coolant level sensor
(2) Coolant level sensor
Thoroughly inspect connectors (1) and (2). Also inspect the wiring from the ECM to the coolant level sensor. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 4 g01093451
P2 ECM connector
(P2-4) +8 V digital supply
(P2-5) Digital sensor return
(P2-6) Coolant level sensor
Perform a 45 N (10 lb) pull test on each of the wires in the circuit that is associated with the digital sensor supply.
Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and wiring for abrasions and for pinch points from the sensor to the ECM. Expected Result:The harness and the wiring are OK.Results:
OK - Proceed to Test Step 2.
Not OK - Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Verify that all of the seals are properly in place and verify that the connectors are completely coupled.Verify that the repair eliminates the problem.STOPTest Step 2. Check for Active Diagnostic Codes
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Turn the keyswitch to the ON position.
Monitor Cat ET for active diagnostic codes. Check and record any active codes. Note: Wait at least 15 seconds in order for the diagnostic codes to become active.Check for the following diagnostic codes for the digital supply:
41-03
41-04 Expected Result:No diagnostic codes that relate to the digital supply are active.Results:
OK - No diagnostic code for the digital supply is active. Proceed to Test Step 3 in order to verify that the sensor is receiving the correct supply voltage.
Not OK - Active 41-03 - A 41-03 diagnostic code is active. Proceed to Test Step 3.
Not OK - Active 41-04 - A 41-04 diagnostic code is active. Proceed to Test Step 4.Test Step 3. Check for Supply Voltage at the Sensor's Connector
Turn the keyswitch to the OFF position.
Disconnect the harness connector for the coolant level sensor.
Turn the keyswitch to the ON position.
Measure the voltage between terminals A and B at the harness connector. Expected Result:The voltage is 8.0 0.4 VDC.Results:
OK - The voltage is 8.0 0.4 VDC. The voltage is correct. The problem appears to be resolved.Repair: Connect the sensor's connectors. Clear