GLASS 9D1588 - Caterpillar

Possible Causes for an FMI 2 and FMI 8 Diagnostic code are:
There is debris in the sensor.
The energize wire is shorted to the ground circuit while the machine is in operation.
The energize wire is shorted to +battery.
An open circuit exists.
The sensor has failed.
The ECM has failed. An ECM failure is unlikely.Note: Prior to beginning this procedure, inspect the harness connectors that are involved in this 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 the diagnostic code is active before performing a troubleshooting procedure. For sensors powered via the fuse panel, check the condition of the appropriate fuse before beginning the troubleshooting procedure.
Illustration 1 g06027028Note: The diagram above is simplified schematic of the Machine ECM connections. The schematic is electrically correct. However, not all the possible harness connectors are shown. Refer to the latest revision of theElectrical Schematic for the complete schematic.
Table 2
Troubleshooting Test Steps Values Results
1. Identify Active DTC Code Associated With Sensor Circuit
Code present
FMI 2 diagnostic code, proceed to Test Step 2.
FMI 8 diagnostic code, proceed to Test Step 2.
Begin Process For FMI 2 and FMI 8 Troubleshooting HERE
4. Check Supply Voltage to the Sensor.
B. Turn the key start switch and the disconnect switch OFF.
C. At the back of the sensor, spoon into the supply contact.
D. Turn the key start switch and the disconnect switch ON.
E. Measure voltage between the supply contact and frame ground.
F. Gently pull on the wires and move the wires in