GAUGE & CAP AS 1Q3828 - Caterpillar

Illustration 1 g01261883
Service Brake Pedal Switch connectionsThis diagnostic code is associated with the Service Brake Pedal Switch. The switch supplies two switch to ground type inputs to the Machine Control ECM. The ECM expects one of the two switch inputs to be grounded at all times. When the ECM detects that neither of the switch inputs is grounded, the ECM will activate an FMI 03 diagnostic code for voltage above normal.Possible conditions that can cause this diagnostic code are listed:
A switch circuit is open in the machine harness.
A switch circuit is shorted to a voltage source.
The switch has failed.
The ECM has failed. This is unlikely.System Response:When the ECM activates this diagnostic code, the ECM will stop operation of the machine and disable the main machine systems. The oscillating axle will be locked, machine travel will be disabled and the starter relay will not energize.Note: Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, secure and in good condition. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure. Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected.Test Step 1. CHECK THE SWITCH INPUT CIRCUITS FOR AN OPEN
Turn the disconnect switch and the key switch to the OFF position.
Disconnect the machine harness connector from the switch.
At the machine harness connector for the switch, connect a jumper wire between the normally open (N/O) contact C (wire F787-GN) and the normally closed (N/C) contact B (wire F790-BR).
Disconnect the machine harness connectors J1 and J2 from the Machine Control ECM.
At the ECM machine harness connector J2, measure the resistance between N/O contact J2-30 (wire F787-GN) and N/C contact J2-31 (wire F790-BR).Expected Result:The resistance measurement is less than 5 ohms.Results:
OK - The resistance measurement is less than 5 ohms. The switch input circuits are not open in the machine harness. Proceed to Test Step 2.
NOT OK - The resistance measurement is greater than 5 ohms. One of the switch circuits is open or has a poor connection in the machine harness. Repair: There is an open or a poor connection in switch input wire F787-GN or switch input wire F790-BR. Check each circuit individually in order to determine which circuit has the problem. Refer to the complete machine Electrical System Schematic. Verify that all connection points for the circuit are clean, secure and in good condition. Repair the machine harness or replace the machine harness. STOPTest Step 2. CHECK THE SWITCH GROUND CIRCUIT FOR AN OPENThe disconnect switch and the key switch remain in the OFF position. The machine harness connectors remain disconnected from the ECM and the switch.
At the machine harness connector for the switch, connect the jumper wire that was used in