Throttle Position Sensor: Description and Operation

Throttle Position (TP) Sensor:

PURPOSE
Used as an input to determine shift scheduling and Electronic Pressure Control (EPC).

LOCATION
Mounted on the fuel injection pump lever.

OPERATION
The Throttle Position (TP) sensor is a potentiometer that detects the position of the throttle lever and sends this information as a voltage signal to the Powertrain Control Module (PCM).

If a malfunction occurs in the TP circuit, the PCM will recognize the TP sensor signal is out of specification. The PCM will then operate the E4OD transmission in a high capacity mode to prevent transmission damage. This high capacity mode causes harsh upshift and engagements.

SYMPTOMS
Harsh engagements, firm shift feel, abnormal shift schedule, abnormal or no torque converter clutch operation. May flash Transmission Control Indicator lamp (TCIL).

DIAGNOSTIC TROUBLE CODES
23, 33, 43, 53, 63, 73, 121, 122, 123, 167.