Speedo and Tranny Problems

TMCNALR

MEMBER
1997 PLYMOUTH VOYAGER
6 CYL
FWD
AUTOMATIC
196,000 MILES

97 Plymouth Grand Voyager 3.3 l 3 speed tranny 196 k problems started with instrument cluster acting up no speedo no tach pulled dash and plugged harness in better and got gauges back (AC blower motor also hadn't been working but came back to life). Drove 20 miles and was coming to a stop when all of a sudden it went to limp mode. All gauges work except speedo. Stop by Autozone and run codes come back with P0700 transacle control system fault. P0715 Input sensor 1 circuit. P0720 low output speed sensor above 15 mph Limp it home, checked fuses, relays, ground wires. Unplugged and replugged sensors on tranny. Started back up and it tries to go into gear but doesn't catch. When KOEO the chime comes on and the speedo jumps to 120 and then back down beyond my scope of experience! Any help would be greatly appreciated! It's mom taxi so the whole family is affected mom isn't happy nobody is happy!

3 Replies

CARADIODOC

MECHANIC
33,916 POSTS

Based on the multiple symptoms, I would suspect one of the two speed sensors first. An electrical problem such as a corroded connection can send it to limp mode as soon as you shift into drive, but a mechanical problem, such as metal filings stuck to the magnets won't show up until you start to move. If it always goes into limp mode right after or during an up-shift, slippage in one of the clutch packs is more likely.

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Sunday, April 10th, 2011 AT 2:26 AM

TMCNALR

MEMBER
8 POSTS

Ok, replaced both sensors and the speedo is working fine. The van will quick shift but will not go into high gear. My question is this happened after electronics freaked out while sitting in the driveway, messed with instrument cluster and everything started working again. (Including the AC blower motor and blinkers) Drove the vehicle 20 miles then out of the blue, without warning, shifted fine without issue then jumps into limp mode. To me it seems more electrical than mechanical. (The blower motor and blinkers are not working again) Is there somewhere I should be looking based on this feedback? Thank you for all your help!

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Thursday, April 14th, 2011 AT 5:49 PM

CARADIODOC

MECHANIC
33,916 POSTS

You might suspect the ignition switch. It's common for the contacts to overheat, especially if you use the heater fan on the highest setting often. Also look at the electrical connector for the switch to see if two terminals are overheated and the connector body is melted. If they are, those two terminals can be cut out and replaced individually.

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Thursday, April 14th, 2011 AT 6:23 PM