SLUG 2M1168 - Caterpillar

The decelerator position sensor provides the throttle signal to the ECM.
Illustration 1 g02305153Mounting location of the decelerator position sensor on the decelerator pedal (typical example)The decelerator position sensor is mounted to a pedal assembly that allows the operator to control the speed of the engine. The geometry of the pedal assembly controls both the travel of the sensor and the range of the output signal. The decelerator position sensor cannot be adjusted.The output from the decelerator position sensor is a PWM signal that varies with the position of the decel pedal. The decelerator position sensor produces a minimum duty cycle in the released position and a maximum duty cycle in the fully depressed position. When the pedal is released, the ECM translates the output signal of the sensor to a position of 0 percent deceleration. When the pedal is fully depressed, the ECM translates the output signal to a position of 100 percent deceleration.The decelerator position sensor is powered by 8.0 0.4 VDC that is provided by the ECM. A digital return for the sensor is also provided by the ECM.The ECM uses an automatic calibration function that allows the ECM to minimize the deadband of the sensor. The automatic calibration function assumes a range of PWM duty cycle at powerup. If the duty cycle of the sensor exceeds this initial range, the automatic calibration function adjusts the limits of the duty cycle. The ECM input is then calibrated for the new range.
Illustration 2 g02305733
Schematic for decelerator position sensor
Table 2
Troubleshooting Test Steps Values Results
1. Inspect the Electrical Connectors and the Wiring
A. Turn the main disconnect switch to the OFF position.
B. Thoroughly inspect the connectors. Refer to Troubleshooting, "Electrical Connectors-Inspect" for more information.
C. Perform a 45 N (10 lb) pull test on the connector wires.
D. Check the harness for abrasions and pinch points.
Electrical Connectors and Wiring
Result: The connectors and wiring appear to be OK.
Proceed to Test Step 2.
Result: There is a problem with the connectors and/or wiring.
Repair: Repair or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are coupled.
If the problem is not resolved, proceed to Test Step 2.
2. Inspect the Decelerator Pedal Assembly
A. Inspect the throttle pedal assembly for components that are loose, bent, missing, or worn.
B. Slowly depress the pedal and release the pedal.
Throttle Pedal Assembly
Result: The throttle pedal assembly functions properly.
The mechanical condition of the throttle pedal assembly is OK. Proceed to Test Step 3.
Result: The decelerator pedal assembly is in poor condition.
Repair: There is excessive drag or improper operation of the decelerator pedal assembly. Repair the pedal assembly or replace the throttle pedal assembly, as required.
If the repair does not eliminate the problem, proceed to Test Step 3.
3. Check the Status for "Decelerator Position" on Cat® Electronic Technician (ET)
A. Connect Cat ET to the service tool connector.
B. Turn the keyswitch to the ON position.
C. Observe the status for "Decelerator Position" on Cat ET while you operate the throttle pedal through the entire range of