Automatic trans having overdrive issues
 

Hey fellas. '96 dodge 2500 transmission is having trouble staying in overdrive. It'll go in but kick out reletively soon after wards. Couple seconds. I took it to the shop last night to get it looked at because the RPMs at 65mph are 2350. He told me it could be the Throttle Position Sensor, the computer needs flashed, or the transmission is bad. I have 3.54 gears coming to get the RPMs down and back into the power band from Pukie370 and I'm going to order the 3K GSK kit this weekend so that the truck will fuel beyond where it maxes out right now. I'm having the pressures in the tranny checked next weekend and that's where my question comes into play. Anyone around Dayton know how to flash a computer and what are some other causes that I could look into.
Thanks

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Oh and another thing, The brake safety for shifting out of park is disabled and the column is a little off on the gear selector. Also, the overdrive control switch dissables 4th gear, not the overdrive gear

I would def check out the TPS. There's a good how-to here:

Dodge diesel maintenance tips

Not quite halfway down the page.

Holy cow that is amazing information. I'll try that this weekend and get back to you
:tu:

check your brake switch... they can cause alot of problems. try holding the pedal up

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sometimes the trans temp sensor goes for a shit and it'll shift pretty funky... i ran a 1k resistor when mine went for a shit and runs great....

Well it's been raining non stop here in ohio for the last 2 weeks so I haven't had a chance to get under it. This weekend I'm putting a 2" body lift just to get the front end off my tires a little bit and while the cab is up, I'll check the tranny temp sensor and the vacuum lines on the transfer case

well trannys are my weak point but i have learned alot from people here. so here goes: first off there is no overdrive "gear" its actually the torque converter locking up giving you a higher ratio. with that said this problem sounds a little bit like the torque converter isnt locking all the way or it is and then its unlocking some time there after. if im right then your issue is probably an electrical issue whether it be the tps or any wiring that could be damaged. OR it could be an internal problem with the tranny/tc. If after some further diagnosis on your part and you cant fix the problem i would suggest a lockup switch. I have 95 and i went through the same problem your going through and i was suggested the switch and problem solved/bypassed.

That's not accurate. 4th gear is "overdrive" and tcc lockup will drop RPM's further.

The Torque converter locks up fine but the gear itself doesn't stay in. If I roll into 4th from 3rd, the TC will lock and I'll have lots of power for a quarter mile. Once the RPMs defuel at 2300, it unlocks and shifts down to 3rd again. If I stay at 2000 RPMs and about 55 mph, it will shift back and forth from 3rd to 4th. It's not the brake switch, I checked that. The tranny guy said probably the TPS or the computer. I found how to adjust the TPS and I'll try that when it stops raining. Hearing you say it though helps me to believe it might be that and not the actual tranny going out.

sorry for bringing an old thread back to life but im having the same issue on my 98.5 3500 4x4 truck is bone stock,and the trans was replaced 60k ago by previous owner. same happens to me, 55mph at 2k rpm and it waffles between 3rd and 4th, same thing happens at 65 and 75. any faster or any slower and it wont do it. I am guessing that it will likely be my tps or computer as well? and should i try adjusting the tps before anything else? i really dont have the funds to replace the trans if its a bigger issue.

Its most likley going to be a speed sensor in both cases ... a TPS will do it to all gears .... speed sensors will sometimes only effect OD and or Lock up .... cheep and easy as heck to get too .... even in the rain .... :tu:

keep posted :pca1:

i like the sound of that cause i was talking to a buddy today and he was saying that it could be the shift control module inside the trans and i didnt feel like spending the 3-500$ to fix it. I'll look into getting a new speed sensor and see if that fixes the issue.

speed sensor should be around 45-65 bucks .... not real cheep .. ut cheeper than other ideas ....

also , might wanna drop the pan and do a filter change .... just for good measure and to ensure that its not the issue :tu:

be sure to check the ATF with the truck level, idle, warmed up and in NEUTRAL.

if you check it in park it will read full when it is actually 1-2 quarts low. this will cause hunting between gears an random TQ converter locking and unlocking...

I actually checked it toda after a 40 mile drive in natural and it was full and looked brand spank in new. I've only had the truck 2 months and I believe they serviced the trans when they did my fuel system upgrades before putting the truck on the lot. As for the speed sensor auto zone has them for 20$ I'll double check and make sure that's the correct one.

I would do the service again ..... just because I know they use cheep fluids and such ... and it dosent mean that it wasnt full of crap and now has partially plugged the "new" filter they installed .... ya know

and the speed sensor should be 45-60 20 is way too cheep ..... keep in mind you get what u pay for ...:argh:

true, they might have used Dextron/Mercon standard fluid. these transmissions require ATF+. when I installed my Goerend Trans i used ATF+4 as it was the only full synthetic I had access to at the time.

So i went and got the sensor today, paid 42 for the better one with lifetime warranty. I will take into consideration what you said about doing the service again as well. my question is should I have a shop do it so they can pump the torque converter too?

they can only pump the TQ if the trans is removed as it is an internal part when installed, but yes I would have a reptuable shop do the work and adjust your Line pressures for better shifts also, somewhere in the 160-175 range for Daily dirving should be more than enough... :tu:

Sweet deal, I don't even daily it, I only drive it every few days. and only tow like 5k max. I will search for a good shop to do the service. Thanks for the help.

Ur in burlington wa, heck I'm in tacoma, olah local bomber:jump:

Haha I just noticed that too. kinda nice to have a somewhat local guy to talk to and get advice from Lol. Especially since this is my first diesel

Well, Might have to make the short road trip and bring my tool box so we can bomb ur's up to par :tu: :rocking:

I'd be down for that. Just don't have money for parts Lol. I picked up my Buddys old stock exhaust that I'm going to use to splice together a straight pipe setup to get it breathing a little better till I can afford the diamond eye 4" setup. Oh on another note I fixed my trans today, swapped the speed sensor out for a new one and bam no more shift issues. At least not yet.

theres some good reading here

so as of today still no shift issues, glad someone suggested the speed sensor, was a super simple fix and fairly in expensive. i also noticed my truck was sluggish and had a weird whine noise coming from the turbo, decided to check all my v bands and guess what almost all were loose, including the one from the turbo to the elbow. tightened everything up and holy shit its like driving a brand new truck. no more whine, gobs of torque and hp and gets off the line like my old drift car used to. i love it .:rocking:

Be careful, dont wanna blow a HG with all that new power..LOL :td::argh:

Its still stock Lol I'm not to worried about that happening. but I will be careful for sure. I can't afford to do a head gasket.

keep in mind

add fuel = added cylinder pressure
add timing = added cylinder pressure
add boost= added cylinder pressure


See where this is going ?

be gentle off the line and at low RPM's ... you more likley to pop one at low than at high ....

Also there is a plug above the thermostat housing , and one at the back of the head, do your self a favor and make a good "high pressure line" between thermostat housing and the rear of the head.... the water pump will also push real hard up on the head and with more pressure on the head bolts and it will begin to leak righ under the thermostat housing .... I have pics of mine .... thats what happened to me :td: majorly sucks

If you could post the pics that would be helpful. I didn't think it would affect it since its still stock but I will keep all.of what you've said in mind, and since mine is a 24v I have to be careful anyway because they already have fuel issues. luckily mine was taken care of before I bought the truck. I've heard running a coolant filter setup is also a good idea on these, is that true ?

Hey guys, I'm having a similar problem with my 1996 when in overdrive. When cruising around 1500-1800 on the hwy, it will rev up like the trans kicks out for a quick second, then returns to normal. It will twitch like this every couple minute or so. Could this also be the speed sensor? If so, engine speed sensor or trans speed sensor?
thanks!

Yes, the output speed sensors are a notorious soft spot. Every one I build gets a new one.
They're only about $15 and take about 5 minutes to change, so it's a cheap endeavor...

Thanks Dynamic, I will change it out. Not a peep out of the transmission today, its always so random, but becoming more frequent. I'll pick one up at the dealer tomorrow.

Good to know :c: