GEAR 2W0499 - Caterpillar

This procedure covers the following diagnostic codes:
Table 1
Diagnostic Trouble Codes for Analog Throttles
J1939 Code CDL Code Code Description
(code descriptions may vary) Comments
29-2 774-2 Accelerator Pedal Position 2 : Erratic, Intermittent or Incorrect The ECM detects the following condition:
The signal from the analog throttle position sensor is invalid.
If equipped, the warning lamp will come on. The diagnostic code will be logged.
91-2 91-2 Accelerator Pedal Position 1 : Erratic, Intermittent or Incorrect
91-3 91-3 Accelerator Pedal Position 1 : Voltage Above Normal The Electronic Control Module (ECM) detects one of the following conditions:
The ECM has been powered for 3 seconds.
Diagnostic code 168-4 is not active.
3509 (262) codes are not active.
The setting for the upper diagnostic limit has been exceeded for one second.
If equipped, the warning lamp will come on. The diagnostic code will be logged.
29-3 774-3 Accelerator Pedal Position 2: Voltage Above Normal
91-4 91-4 Accelerator Pedal Position 1 : Voltage Below Normal The ECM detects one of the following conditions:
The ECM has been powered for 3 seconds.
Diagnostic code 168-4 is not active.
3510 (2131) codes are not active.
The setting for the lower diagnostic limit has been exceeded for one second.
If equipped, the warning lamp will come on. The diagnostic code will be logged.
29-4 774-4 Accelerator Pedal Position 2: Voltage Below Normal
Follow the troubleshooting procedure to identify the root cause of the fault. If a fault occurs with the primary throttle with secondary throttle is installed, the secondary throttle will be used until the fault is repaired.If a fault occurs with the secondary throttle, the engine will use the primary throttle until the fault is repaired.If a functional throttle is not available, 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.The diagnostic codes above relate to an analog sensor. Use this procedure only if the analog sensor uses an output from a variable resistor.The sensor is most likely to be mounted on a throttle pedal. The sensor is attached directly to the throttle assembly. The sensor provides an output voltage to the ECM. The sensor output voltage will vary with the position of the throttle. Foot operated or hand operated throttle assemblies are available.The sensor receives +5 VDC power from the ECM. The sensor will produce a raw signal voltage that will alter between low idle and high idle. The voltage is changed into a throttle position within the range 0% to 100% by the ECM.The sensor senses the speed requirement from the throttle position. A second sensor may override this speed requirement from the first sensor.