ENGINE AR-CORE 1208242 - Caterpillar

Table 1
Diagnostic Trouble Codes for Throttle Switch
J1939 Code CDL Code Code Description
(code descriptions may vary) Comments
29-2 774-2 Accelerator Pedal Position 2 : Erratic, Intermittent or Incorrect The Electronic Control Module (ECM) detects the following condition:
There is an invalid combination of positions for the multi-position switch.
If equipped, the warning light will come on. The ECM will log the diagnostic code.
91-2 91-2 Accelerator Pedal Position 1 : Erratic, Intermittent or Incorrect
Follow the troubleshooting procedure in order to identify the root cause of the fault. If the application is equipped with two throttles, the engine will use the second throttle until the fault is repaired.If a second throttle is not installed or if the second throttle has a fault, the following conditions will occur:
The engine will default to the limp home speed.
If the engine speed is higher than the limp home speed, the engine will decelerate to the limp home speed.
If the engine speed is lower than the limp home speed, the engine speed will remain at the current speed.
The engine will remain at this speed while the diagnostic code remains active.
All inputs from the faulty throttle are ignored by the ECM until the fault is repaired.
All inputs from the repaired throttle will be ignored by the ECM until the keyswitch has been cycled.Check that the software configuration in the ECM is correct for a multi-position throttle.If the engine has an analog throttle with an Idle Validation Switch (IVS), then refer to Troubleshooting, "Idle Validation - Test".The throttle switch provides the operator with the ability to select the desired engine speed. The throttle switch configuration may be selected between 0 to 4 switches. A multi-position rotary switch may be used.The throttle switch is typically connected to the four throttle inputs of the ECM. Each position generates a specific ON/OFF pattern on the throttle inputs. A diagnostic code is generated if a pattern that does not correspond with any of the switch positions is detected.Once a diagnostic code is generated, the ECM ignores the throttle input signals. The desired engine speed is set to low idle if no alternative throttle is detected.Voltage at the throttle inputs to the ECM should be 13.8 0.5 VDC when the throttle inputs are open. The voltage should be less than 0.5 VDC when the throttle inputs are closed.During the following procedure, refer to the electrical schematic for the application.Complete the procedure in the order in which the steps are listed.
Table 2
Troubleshooting Test Steps Values Results
1. Inspect Electrical Connectors and Wiring
A. Turn the keyswitch to the OFF position.
B. Thoroughly inspect the P1 connector and any other connectors that are included in the application for this throttle switch. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
C. Perform a 45 N (10 lb) pull test on each of the wires in the switch connector and the ECM connector that are associated with the active diagnostic code.
D. Check the screw for the ECM connector for the correct torque of 6 N m (53 lb in).
E. Check the ground