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2006 Chrysler Pacifica Touring P0700 P0720 P0731 Fault: Transmission Slams, Speedometer Erratic, Gears Not Shifting

Model: Chrysler Pacifica Touring Fault Code: P0700 Posted: 2015-06-08 17:58

My 2006 Chrysler Pacifica Touring is displaying diagnostic trouble codes P0700, P0720, and P0731. I have already replaced both the input and output speed sensors, and the transmission fluid has been flushed and checked—no signs of contamination or burning. The check engine light returns immediately after reset, and the vehicle exhibits severe shifting issues: it lunges at stops and fails to shift properly. When idling in gear (D, N, or R), the speedometer reads between 20–30 mph while stationary, behaving like a tachometer. After resetting the transmission control module, the car drives smoothly for about one mile before repeating the lunge behavior. In rare cases, the vehicle gets stuck in a single gear and won't disengage until manually placed into neutral. I've tried multiple resets with no lasting fix. What could be causing this? Are there known solutions or common fixes for these specific codes on the 2006 Pacifica Touring?

Related fault codes
P0700P0720P0731
Comments (5)
Anonymous 2015-06-09 06:49

The speedometer reading 20–30 mph while stationary in D, N, or R—does this occur only when parked? Can you clarify if the issue happens consistently across all gears and whether it's related to sensor input or a transmission control problem?

Anonymous 2015-08-09 14:43

I experienced similar symptoms when my alternator failed. The tachometer-like behavior and erratic idle were present, along with rough shifting. Checking the alternator for diode failure is a recommended first step.

Anonymous 2015-09-30 06:34

Hi 'Bear'! I'm having the exact same issue on my 2006 Chrysler Pacifica Touring—same codes (P0700, P0720, P0731). The speedometer reads 20–30 mph when parked in D, N, or R. About four seconds after stopping, the transmission slams and re-engages, causing a lunge. On a few occasions, it's stuck in one gear and won't shift out unless I manually put it into neutral. I've already replaced the output speed sensor and its pigtail. This is very frustrating—any insight or fix would save me from costly repairs? Thanks for your help!

Anonymous 2015-09-30 11:10

Start by testing the alternator for diode failure. A failing alternator can cause electrical noise that interferes with transmission sensor signals, leading to erratic behavior and false speedometer readings.

Anonymous 2015-10-28 17:04

CarterLumberSalesGuy wrote: Hi 'Bear'! I'm having the exact same issue on my 2006 Chrysler Pacifica Touring—same codes (P0700, P0720, P0731). The speedometer reads 20–30 mph when parked in D, N, or R. About four seconds after stopping, the transmission slams and re-engages, causing a lunge. On a few occasions, it's stuck in one gear and won't shift out unless I manually put it into neutral. I've already replaced the output speed sensor and its pigtail. This is very frustrating—any insight or fix would save me from costly repairs? Thanks for your help! I own a 2003 Chrysler Grand Voyager with identical symptoms: P0700 and P0720 codes, engine light on, and when in D, N, or R, the speedometer reads up to 60 km/h while stationary. A shop suggested the transmission is failing—this would be expensive. Have you found a solution? Is it possible that a sensor replacement or transmission fluid change resolves this issue?