Mechanics

SPEEDOMETER & ODOMETER NOT WORKING, TRANSMISSION IN "LIMP MODE"

1997 Dodge Caravan • 145,000 miles

Greetings! Upon completing the repair of an ignition issue, I'm noticing now that our Grand Caravan has another problem: the speedometer stays at zero; digital odometer lights up, but does not advance as miles are driven; car is "limp mode" (2nd gear only, will not shift to higher gears). OBD2 codes reported are P0731, P0500, P0700.

P0500 indicates possible electrical connection problem or failed vehicle speed sensor. Here are my questions:

- Is this Vehicle Speed Sensor (VSS) different from the transmission input & output speed sensors?

- Assuming this is a different sensor, where is this VSS located? (I have found the location of the two transmission speed sensors.) Does anyone have a photo or diagram showing this VSS?

- Is this VSS likely the cause of these symptoms? Can a failure in the VSS cause the transmission to go into limp mode? Or does that indicate it is more likely the transmission input or output speed sensor? (Would then cause the speedometer and odometer to stop working)?

- Is there any chance that the Transmission Control Module itself has gone bad?

- Or could I have possibly done anything (while replacing the ignition switch) that could cause such symptoms? Or is this totally unrelated?

Thanks much for your help, John : )
Avatar
Jpoliver
July 15, 2012.




What liter engine?


Tiny
Rasmataz
Jul 15, 2012.
Hi, Engine is 3.3 L. And, by the way, I should clarify that it was the ignition switch issue (in the steering column) that I had worked on previously.


Tiny
Jpoliver
Jul 15, 2012.
Been checking on it in Mit1/Prodemand-but to no avail on the VSS for a 3.3 liter the 2.4/3.0 has it-find the outshaft speed sensor and inspect and test it then comeback with some results


Tiny
Rasmataz
Jul 15, 2012.
Hi, Thanks for your reply. I have found instructions/photos online to find and remove the transmission output sensor. Is there a way to test the old sensor, other than to just purchase a new sensor, install it, and see if that fixes the problems?

Thanks, John : )


Tiny
Jpoliver
Jul 15, 2012.
Go to this link and see if it helps: http://www.youtube.com/watch?v=AgI9XG3OmS4
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Tiny
Rasmataz
Jul 15, 2012.
Hi, I wanted to write and give you an update: Yesterday I called the parts dept. Of a couple Dodge dealers. It seems that the separate (3 wire) vehicle speed sensor (that autozone wanted to sell me) is for the 3 speed transmissions, not mine (which is apparently a 4 speed). So, it seemed that the tx output sensor was probably the VSS that drives my speedometer. I went ahead and ordered new input/output sensors on ebay yesterday. They should arrive in a few days.

This evening I swapped the EATX fuse and relay (with the fuel pump ones) to make sure the problem was not a fuse/relay issue. No change.

Then I started working toward the sensors. I undid the 10 mm bolts and hose clamps around the air lines (to get to the area where I could start to work on the input and output sensors).

With my flashlight I found what I thought was the correct location for the output sensor, but there was nothing hooked up to it? I looked around for a loose cable. I couldn't find it at first, but then I saw it laying on another hose down below. So I connected it up and that fixed it!

How did it get disconnected? Could it have just fallen off? I don't know. In any case, hopefully it will stay on.

Thanks again very much for your help!

John : )


Tiny
Jpoliver
Jul 18, 2012.

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