have a 2002 dodge grand caravan es awd 3.8l. my speedometer was going crazy now not working at all or cruise control. changed the input and output speed sensors still nothing. took it to auto zone free code readings 1. P0700 GEAR ratio error first gear 2.P0500 vehicale speed sensor circuit condition the ecm has detected a fault in the vehicle speed sensor circuit something about short circuit. 3.P0731 gear ratio error in first gear something about the ecm has detected that the transmission input rpm does not match the transmission output rpm poor electrical connections. where do i start? my trany guy said its not the trany. my van has autostick and thats not working either should i rewire the whole tcm? can it be a ground wire????????? no one seems to actually know.

 

if you have fixed the problem with installing new speed sensors you may have to reset the ecu by disconnecting the battery and waiting overnight. also check for fuses that may have blown. and vaccum lines on or near the intake if you can get to them. i find it hard to believe a bad ground wire on such a late model vehicle to be the problem, hope this helps.

 

can it have anything to do with the speed control servo? i seen something in the book about it its under the battery.

 

P0700 is a "Transmission Control System Malfunction". That is telling you the TCM has stored a transmission fault code. This is not a normal powertrain code read by an Autozone scanner. This has to be read by a scanner capable of reading two digit transmission fault codes.

Barring the code, I would be verifying continuity on the speed sensor wires from the sensors to the TCM. You could try an instrument calibration/test listed in the Tizzy1 DIY thread at the top of the forum to see if the speedo will move and read correctly. This could wind up being a bad TCM ($150 - $300).

 

went to the dodge dealer, got new output speed sensor harness, on the tcm i found where the green wire went, when looking at it from the side where the holes go on the pins, it was the 8th one down from the left. i sniped the wire ran it to the sensor and the other wire to the ground wire and bingo. thanks people saved a lot of cash.

 

update. put in new starter after it finally kicked the bucket and got my cruise control working speed needle no longer jumps around and auto stick works.