No Overdrive

[Ewright]

Let me start by saying the problem I'm having now is a recent reincarnation of one which was solved by the good folks on this board. The original problem was:



While at highway speeds the trans shifted intermitently out of overdrive, and the speedo dropped to zero. This was fixed with a new speed sensor.



The new one:



While at a highway speed the trans dropped out of O. D. , the speedo dropped to zero and both the trip and odometer stopped working. This was yesterday and no change. My first thought was the speed sensor again since the symptoms seemed the same, so I removed it but the shaft was still square (this was the only thing I knew to look for) Any Ideas? Thanks ahead for your thoughts, ideas and time.



Eric Wright

92 250

 

[Case500D]

Speed Sensor

Ewright,



I would make an educated guess and say that it is the speed sensor, aka the distance sensor. My truck did the same thing. I see that you have replaced yours, but I would make sure the connection is good and there are no broken wires. My old one turned and the shaft was still square, but is was junk. Any more details?



Jeremy

 

[DPKetchum]

I also had a problem with the harness that plugs into the throttle postion switch. At times erritic or no overdrive. Ordered and replaced that harness and its fixed. Try a wiggle and unplug test on that harness first and see if problem is altered.

 

[Ewright]

It's not the speed sensor!

I replaced the speed sensor on Monday, with no luck. Of course it's an electrical part so I can't return it, so I've got an extra one if anybody needs it. After doing that I checked the adaptor which is in between the sensor and the transfer case. Looking inside the adaptor where the gears meet there's broken plastic. Anyway, I believe now it's the adaptor, so I ordered a new one at around 50$ but the one that came in is straight not off set like the original, also the old one I think was for a 3. 54 rear end, a 12 tooth gear on the transfer case and 215/85/16 tires. The new one is for the same rearend, 14 tooth gear and the same tires. Also I've got 235/85/16 tires now. Does anyone know if this will make any difference? I could use some help, it's not turning out to be as straight forward as I thought. It's no fun driving with a max speed of 45mph without O. D. Thanks ahead.

 

[Midnite]

I'm bringing this one to the top again because I think I'm running into the same problem. My speedometer suddenly started bouncing while on the highway, and the transmission dropped out of OD.



Ewright, did you eventually figure out everything on yours?



Thanks,

Mike

 

[DPKetchum]

Speed sensor and or the little harness to the TPS. I bet speed sensor or connector. I wasted $150 on adapters to correct a speedo in accurately because I went from 3. 54 gears to 4. 10. NO ONE in a parts dept could get it straight or make since of adapters. Through trail and error I fitted one of these to one of thats and test drove. When the last try it seemed close had my wife run side by side with our 98 1500 slt and it was spot ON. But between the adapter and the gear it was a mess.

 

[JStraw]

I have to keep a can of contact cleaner handy. Every now and then, the sensor and its connector get gritted up and need a shot of cleaner to get back to normal. Always try the easy and less expensive things first. Sometimes it saves ya money.

 

[farmall]

Since you have tried a new spped sensor 2 times. There is 2 physical things left. One is the Speedo itself, 2 is the computer that is tucked inside the left fender well behind the battery. Before replacing that I would check the connection on the ECM and also the block on the firewall. When my ECM went bad I lost the A/C, charging, crusie, speedo, and grid heater. Also make sure that the gear is turning inside that runs the speed sensor shaft.



Bill

 

[John Martines]

I had same problem and found that the offset adaptor gears were toast. I have 3. 54 rear also the part number for the offset adapter is 4428548 and the 16 tooth adapter is 4329816 hope this helps.

 

[Ewright]

Final outcome

I've been out of the country for awhile so I apologize for taking so long to post the outcome. After 2 or 3 attempts to order the right part and a couple 2hour round trips to pick up the wrong parts we finally figured it out. If you read the original post, the first time this happened it was the speed sensor, with the same symptomes this time it ended up being the adaptor the SS screws on to. Now this would have been easy enough except that neither the part or the number were listed in the parts computer at the dealership. So finally dodge was called and we got the correct number. If I'm correct the Part # is: 04428549 ($72. 96). So far this seems to have fixed it so I've got my fingers crossed.



Eric

 

[SClements]

I've run into the same problem before, and of course the dealer has a hard time getting the right part when things have changed, like tires, gears, etc. I've gone to a local speedometer shop and they hook up the speed sensor staight to the trans, dyno run it to see how far off it is, and then they can make an adapter to correct the speedo. They can make the adapter any ratio it takes to make it exactly right.

 

[Midnite]

Well, yesterday after work I was going to pull out the speed sensor and adapter to see how they looked, and the outermost one (not sure which was the adapter, and which was the speed sensor) to which the wires connected to was a little loose. The square needle thingy wasn't being held in all the way, and was starting to round off.



Anyhow, I just tightened everything up and now I have both a reliable speedometer, and a working 4th gear!



Mike

 

[DPKetchum]

AND LET THERE BE OVERDRIVE!