My dad has a 98.5 24v auto and is having a problem with his transmission dropping out of overdrive at OD speed. He said it's intermitent and has happened at 40, 50, 60 and even 70 mph. He took it to the dealer but they said they won't do anything until it throws a code. &gt;<br><br>I think I remember others having this problem and it being a sensor somewhere but can't seem to find the thread...<br><br>Thanks

 

Contact Bill K. at DTT transmissions. DTT.

 

Might be the output shaft speed sensor going bad. It is located on the left side of the overdrive unit, behind the trans. Also, the vehicle speed sensor is located on the top of the differential at the rear, and that is a common failure.

 

Thanks for the reply's, I thought I had previously read there were a couple of sensors that affected the OD. Dad has an appointment at the dealer on Monday with the &quot;transmission specialist&quot;. He is hoping it will act up for him when he checks it out. Only 3 months left on his powertrain warranty...

 

Update: Turns out the trans wasn't dropping in and out of OD but the TC was locking and unlocking. The guy at the dealer says he's 99% sure he just needs a computer reflash to fix this. ??? Does this sound right? Turns out it's not under warranty after all...

 

I just had the flash done on my 99 and so far so good after 2k miles. The tech said it cures 50 to 80% of the trucks. There are several threads on the tcc lock prob.

 

Some of those are caused by noisy TPS signal. There have been numerous posts on the subject, the most common cures I can recall are:<br>a. The reflash, which presumably changes the closed-throttle unlock threshold and/or delay <br>b. Removing the TPS wires from the harness to the PCM<br>c. Cleaning the TPS with contact cleaner<br>d. Replacing the TPS<br><br>A TCC lockup controller can cure the symptom altogether by not allowing the TCC to unlock when the throttle is closed. You can take a look at my company web site www.emjay-eng.com, we make such a controller.<br>

 

Had him reset the APPS and this cured the lockup problem. He hadn't told me initially but now tells me he is also having a problem with his cruise control. He sets it at 60 and cc accelerates to 70 then over time will settle back to 60. The threads I found say the reflash fixes this. But for now he is happy that the lockup problem is cured and also says it is shifting better.<br><br>Thanks for your replies and suggestions

 

got the same truck...did the same thing, the re-flash cured it...good luck

 

I saw this thread, and had to add my own experience. BTW, before I do that--thanks for the detailed answers that you all give, that helps folks like me really understand what's going on.<br><br>I just bought a 98 Ram 2500 4x4 24v Diesel Automatic four weeks ago with 135Kmi on it. I brought it to my local mechanic two weeks ago to get some steering components changed, and now the steering is much tighter. But, as I was driving home, the truck started to &quot;buck&quot; in the upper gear (either overdrive or 4th with OD off)--the rpms would go from 2000 to 1700 or so, and back again. It would do this multiple times--just like what you describe in this thread.<br><br>I brought it back to the mechanic, and after joking about trying to make a living off me, I told him to call me before fixing anything. Well, he called up some &quot;experts&quot; and even had a service guy from the dealership take a look. His conclusion--bad transmission, because the pump was shot (not building enough pressure to shift in OD), the seals were gone, and a bunch of other stuff. I ok'd him replacing the tranny--if that is what it took to fix the &quot;bucking&quot;.<br><br>I should have found this thread before I did that...<br><br>$3219 later, I have a shiny new rebuilt tranny, and as I drive it home from the shop, it started bucking again. The mechanic claims that it didn't do it during his test drive, but it's probably the torque converter. He told me to bring it back to him, and he'd have the dealership reflash the computer for free (usually $90+). Aw, how nice... <br><br>I'm picking the truck up today after work with the re-flashed computer. Do you think that I really needed a new tranny, or did he take me for a ride? Frankly, after dropping $18,500 on the truck, I don't have $3200 to spend on a tranny unless I sell a kidney or something. Anyone need a kidney? Low milage, hardly used...<br><br>An interesting note: before the new tranny, when I shifted into drive, it would shift hard. Now with the new tranny it shifts smoother (what I'd call &quot;normal&quot. Would that still warrant a new tranny?<br><br>Thanks in advance for your help!<br>Bob

 

got the same truck w/ 66k miles...i had the reflash done and it helped for the most part but every once in a while it still does the lock and unlock thing. i talked to bill k. at dtt trans. and this is a problem that cant be 100% figured out from what i gathered...the tricks on the above posts do help but i've tried most of them and still, every once in a while it acts up....as for the bucking, that happens sometimes in overdrive especially in the lower rpm's on my truck, you will get a feel for the throttle as you drive the truck more and learn to lighten up on it a bit when the rpm's are really low and your cruising in OD....my truck seems to be it's happiest all the way around at about 2000 rpm's on the highway...as for needing a new trans im certainly NOT a trans. expert but your truck seems to do the same things as my truck and alot of the guys on this site who post also...just my $.02

 

Well, I picked up my truck from the mechanic yesterday. Now it shifts smoothly, and the torque converter seems to lock up strongly. <br><br>After replacing the tranny with a rebuild, they &quot;...flashed the tranny computer, flashed the computer in your dash, and also flashed the Cummins comptuer--just to be sure.&quot; <br><br>In my mind, the flash is what fixed the problem.<br><br>How can I tell (if at all) if I really needed a new tranny??<br><br>PS~I still haven't had any offers on my kidney... Must be a tough market... :P

 

1. The way to tell if you need a new transmission is to look at the old one. Probably too late for that, though. :'(<br><br>2. What kind of truck do you have? Dodge CTD RAM trucks have two computers - The ECM (Cummins) and the PCM (D/C). Did they flash you, too? <br><br>3. Try South America for the kidney business ;D<br>

 

I've got a 98 2500 24v automatic. Took it for a &quot;ride&quot; this weekend, ~290mi. Truck functioned beautifully (at all elevations even, from 5000' to 12000' and back) towing a small boat. <br><br>From what my mechanic said, he already got rid of the old tranny, and said that for the $800 core charge, I could get it back. At this point I think I'll file this under &quot;Expensive Learning Experience&quot;, right next to the $1200 roomate I once had!<br><br>Turns out the kidney market is hurting too... Might as well save it for when the prices go back up.