93 3.3 Grand Caravan

I still have a problem...

I had a problem where I'd be driving on the highway and all of a sudden the
speedo would go to zero and then back to what ever speed it was at. The
lights, radio, etc. all continued to work. When it went to zero and back
you could feel the trans re-engaging. It acted as though it lost power for
less than a second and then came back up. I purchased a new ecu unit from
the junk yard, same numbers. The problem went away and I thought it was the
ecu. Now, 5 months later, I had this happen again. It's intermittent,
doesn't happen very often and leaves no codes. So -- it's tough to
troubleshoot. If the crank sensor was failing, would it react this way ?
I've replaced the relays, ASD and fuel pump. Anyone have any ideas or
suggestions on where to start troubleshooting.

thanks,
nick

 

From what you've written and if you only lose the speedometer and not any
other display gauges, then I'd suspect the original problem was the OUTPUT
SPEED SENSOR. Since the computer loses the output speed, it triggers the
limp mode and shifts the transmission to second gear. When the sensor
signal then comes back into range and operates correctly, the computer
shifts back to the correct gear. When you lose signal completely there
should be a fault code set. This is a 20 something dollar part and takes
about 10 minutes to replace. Good luck.

Bob