Thanks master tech. I'm ordering the parts Monday and I'll give you an update. Have a good weekend.

 

Just wanted to give an update. Pulled governor today and the weight and valve were stuck. Replaced, cleaned and van is running like a champ. Thanks for the help, this ended up being a $65 dollar fix and 4 hours of my time - much nicer on the pocketbook than a transmission shop!

 

I have a 1998 Dodge Caravan with 3 speed A670 transmission. And I have something similar to what is being stipulated in this thread:

1) Engine/transmission surges and wants to shift gears (usually up) when at normal cruising speed (no problem when starting out at stop light, etc.).

2) Speedometer goes haywire (way up to 100 mph) even if traveling at 40, 50 or 60 mph.

3) Transmission is brand new Chrysler OEM that has about 20,000 miles on it since last Spring. But the sensors were not replaced at the time.

I thought the answer was to replace both the input and output speed sensors after doing some research last night.

But then read schematics posted here on this thread and realize that this transmission only has one speed sensor.

Any suggestions for me?

 

After further Google search I found a fellow with same 98 Caravan with 3.0 engine and same A670 transmission and experiencing same problems, i.e. speedometer moving erratically and transmission shifting erratically as well.

He solved problem by replacing Transmission speed sensor. But he also found that the plastic gears on end of sensor needed to be replaced. I have asked him where he found plastic gears but no response yet.

Does anyone here know where to get the plastic gear for the speed sensor that goes on this A670 transmission? By the way the sensor uses 3 wires.

Thanks for all your help.

dennis

 

I just ordered the gear today, it cost $22.00 including shipping.
Will check paperwork and input info ASAP.

 

http://www.transmissioncenter.org/sp...e_and_jeep.htm
Scroll to end of page, hope I was allowed to print the link.
They have all the gears.

 

The 3.0 engine tranny is not the same as the 31TH 3 speed tranny.

 

If plastic gear is bad there may not be anything wrong with the sensor, just the gear.

 

does anyone have a part number for the speed sensor? i think i need this as well.

 

This is a mopar number. 4707839AA