V-BELT 9Q3670 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the electrical system if a diagnostic code in Table 1 is active or easily repeated. Also use this procedure if a problem is suspected with the lighting shutdown timer.
Table 1
Diagnostic Codes Table    
Code and Description     Conditions which Generate this Code     System Response    
1681-5 Lighting Shutdown Timer Relay current below normal     The Electronic Control Module (ECM) has detected a low current in the circuit for the relay control.     The code is logged.
The lighting shutdown timer is disabled.    
1681-6 Lighting Shutdown Timer Relay current above normal     The ECM has detected a high current in the circuit for the relay control.    
Illustration 1 g01379251
Schematic for the lighting shutdown timer (typical wiring schematic)
Illustration 2 g01379255
Terminal locations at the J1/P1 ECM connectors (P1-29) Lighting shutdown timer
Illustration 3 g01379309
Terminal locations for a typical relay
Illustration 4 g01214624
Location of the J1/P1 ECM connectors that are for the lighting shutdown timerTest Step 1. Test the Relay in the De-energized State
Remove the electrical power from the ECM.
Disconnect the relay from the circuit.
Verify the operation of the relay in the de-energized state.
Measure continuity across the following terminals of the relay:
Terminal 1 to terminal 3
Terminal 5 to terminal 2
Terminal 1 to terminal 4Expected Result:The following results were obtained:
Terminal 1 to terminal 3 indicated a short circuit.
Terminal 5 to terminal 2 indicated some measured resistance.
Terminal 1 to terminal 4 indicated an open circuit.Results:
OK - Each measurement was correct. Proceed to Test Step 2.
Not OK - A measurement was incorrect.Repair: Replace the relay and retest the circuit.STOPTest Step 2. Test the Relay in the Energized State
Verify the operation of the relay in the energized state.
Apply 12 VDC across the coil of the relay.
Measure continuity across the following terminals of the relay:
Terminal 1 to terminal 3
Terminal 1 to terminal 4Expected Result:The following results were obtained:
Terminal 1 to terminal 3 indicated an open circuit.
Terminal 1 to terminal 4 indicated a short circuit.Results:
OK - Each measurement was correct. Proceed to Test Step 3.
Not OK - A measurement was incorrect.Repair: Replace the relay and retest the circuit.STOPTest Step 3. Check the Wiring for a Short Circuit
Check the continuity of each wire on the relay connector for a short circuit.
Determine the routing of each individual wire from the relay connector. Disconnect any connectors. Check for continuity between the wire and every wire on the connector.
Measure continuity between the wire and engine ground.Expected Result:Each resistance measurement indicated an open circuit.Results:
OK - Each resistance measurement indicated an open circuit. Proceed to Test Step 4.
Not OK - One of the resistance measurements indicated a short circuit.Repair: Repair the wire or replace the wire.STOPTest Step 4. Check the Wiring for an Open Circuit
Check the continuity of each wire on the relay connector for an open circuit.
Determine the routing of each individual wire from the relay connector. Disconnect any connectors.
Create a short between two wires and engine ground.
Measure continuity between the other end of the wires.Expected Result:Each resistance measurement indicated a short circuit.Results:
OK - Each resistance measurement indicated a short