PISTON AS 6E1032 - Caterpillar

Sensor supply voltage is routed from the ECM to terminal A of each sensor connector. The sensor return is routed from the ECM to terminal B of each sensor connector. The ECM provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.
Illustration 2 g03401543
Sensor connector terminals
(A) Terminal A, sensor supply
(B) Terminal B, sensor return
(C) Terminal C, sensor signalPossible FMI 03 causes are:
Failed sensor
Open sensor supply or ground circuit
Signal circuit shorted to +Battery
Signal circuit open or sensor disconnected
Failed ECMNote: The sensors are not protected from overvoltage. A short from the supply line to the +Battery may damage the sensors. If any FMI 03 diagnostic codes are active, a sensor may have been damaged. Check for any active sensor diagnostic codes to determine if a sensor has failed.Possible FMI 04 causes are:
There is a failed sensor.
Signal circuit shorted to ground.
There is a failed ECM.Use this procedure to troubleshoot the electrical system if:
A sensor supply circuit problem is suspected.
There is an FMI 03.
There is an FMI 04.
Table 2
Troubleshooting Steps Values Results(1)
1. Check for Diagnostic Codes
A. Connect Cat® Electronic Technician (Cat ET) to the machine.
B. Check for diagnostic codes.
Code is not active.
OK - The code is not active.
STOP.
Not OK - The code is active.
Go to Step 2.
2. Check Connectors
A. Inspect the circuit harness connectors.
Connectors are:
* Clean
* Secure
* In good condition
OK - Connectors are OK.
FMI 03 diagnostic code, go to Step 3.
FMI 04 diagnostic code, go to Step 7.
Not OK - Connectors are not OK.
Repair:
A. Correct any connection problem.
B. Verify that the problem is corrected.
STOP.
Begin FMI 03 Troubleshooting Here
3. Check The Control And The Harness
A. Turn ON the key start switch and disconnect switch.
B. Disconnect the harness from sensor.
C. Measure voltage between sensor supply and ground contacts at the sensor harness connector.
Voltage is correct(2).
OK - The voltage is correct.
Go to Step 4.
NOT OK - The voltage is not correct.
Repair -
Verify the code status(3).
STOP.
4. Check For A Sensor Circuit Open
A. Verify that the sensor is disconnected from the harness.
B. Turn the key start switch and the disconnect switch OFF.
C. At the sensor harness connector, place a jumper wire between the ground contact and the signal contact.
D. Disconnect J1 and J2 harness connectors from the ECM.
E. At machine sensor harness connector, measure the resistance from the signal contact to the return contact(4).
F. Repeat the process for the sensor connector.
The resistance is < 5Ω.
OK - The resistance is < 5Ω.
The signal circuit and the ground circuits of the sensor are not open.
Go to Step 5.
NOT OK - The resistance is ≥ 5Ω.
The circuit is open.
Repair:
Correct the open.
STOP.
5. Check Signal Circuit For A Short To +Battery
A. Verify that the sensor and ECM are disconnected from the harness.
B. Turn OFF the disconnect switch and the key start switch.
C. Measure the resistance between the signal and +Battery contacts of the sensor harness connector.
D. At harness connector J1 and J2, measure the resistance from signal contact to all possible sources of +Battery.
The resistance is ≥ 5KΩ.
OK - The resistance