TPS reads throttle plate angle and is mounted to the throttle body shaft. Symptoms of failure: surging, jerky shifts, P0123/P0122, hesitation off idle.
The TPS on the 4.0L is a small black or green sensor mounted to the throttle body shaft. It sends a 0-5 V signal to the ECU correlating to throttle position. Failure produces erratic idle, surging at steady throttle, harsh upshifts (the AW4 takes shift timing from TPS), poor fuel economy, and codes P0121 through P0124. Test with a multimeter: at closed throttle, signal should be approximately 0.8 V, rising smoothly to about 4.5 V at wide open throttle. Any dropouts or 'jumps' indicate a worn track inside the sensor. Two Phillips or T-25 torx screws hold it. The Renix-era TPS is slightly different (a four-wire sensor with idle switch) and not interchangeable with HO. Mopar 53030848 fits 1991-2001. After replacement, no calibration is required on OBD-II (1996+); pre-OBD2 may need an idle relearn via key dance or a few drive cycles.
| Part | Vendor | Est. price |
|---|---|---|
| TPS Mopar (HO) | Mopar | ~$50 |
| Standard TH239 | RockAuto | ~$25 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.