Any advise is appreciated.
Bought this 1990 B250, with unknown (95,000) miles because the odometer was not working. After many repairs to get it road worthy, we discovered it never shifts into 4th gear (OD). And then to top it off I asked my mechanic what tranny fluid he used for the service and it was dexron! Crap! Now it has the wrong fluid too. Does anyone know where to begin on this? I have a diagonistic appointment at the local Dodge dealer.
I'm really hoping this may be somewhat simple to fix, it shifts great from 1-3 so maybe 4th has not been ripped apart by a previous owner. Do I have them check for error codes & the wiring first?
Thanks! Cathy

 

On the assumption that your '90 is the same as my '89. Fourth gear is overdrive, and not quite another gear, but the torque converter will lock up at 47mph. It feels like another gear.

If your Vehicle Speed Sensor is not operating properly, it will not go into overdrive. Or if the ECM is not seeing a signal from the VSS.

If you are getting a code 15, this is your culprit.

Do a search for the Key dance for checking codes. Pretty simple, but so so much to explain.

My VSS is inline, on the speedo cable. Just under the brake booster. It likes to get wet and cause a code 15.
I read sometimes they are mounted on the tranny.

http://contentinfo.autozone.com/znet...SU334/image/6/

It if course could be a mechanical issue as well versus an electrical one. Getting the dextron out is important, but if your needing a rebuild anyway, flushing and refilling with atf+4 is a waste of money.

Autozone will check your codes if you cannot figure out the key dance. I wouldn't goto the dodge stealer unless it if for an ATF+4 flush. And I wouldn't do the flush unless it is going into overdrive and lockup.

 

Thanks LY, yes I think it would be a 3 speed tranny with overdrive. I had it at my mechanic yesterday & he confirmed it wasn't going to OD but said he couldn't find the PCM to check for codes. I felt at that point it was beyond his knowledge & the Dodge dealer was a safer yet way more expensive choice. This info will help me at least sound like I know something about the van when I take it in. Depending on the findings I will then make a plan to change out the fluid.

 

"I had it at my mechanic yesterday & he confirmed it wasn't going to OD but said he couldn't find the PCM to check for codes."



Run away from this mechanic.

You can check the codes easily enough yourself via the key dance.

Turn the key on and off 3 times, the third time, leave the key on and get ready to count the flashing check engine light.

A code 15 will blink once, then pause.
then blink 5 more times.

Code 12 usually comes up meaning the battery has been disconnected within the last 50 starts. code 55 means end of codes.

 

landyacht, just a note: my '90 B250 with A518 did NOT have a lockup converter.

And I agree: run from this mechanic and find a real tranny shop - not a chain - who will diagnose your tranny properly. And fill with ATF+3 or +4.

The Dodge dealer isn't necessarily the best choice, btw. Often, the 'mechanics' there are simply parts changers. I'd find a good, local shop with a decent reputation, myself.

 

Thanks everyone. I will be doing the key dance before I take it in. The mechanic is a reputable local guy, but I think this is beyond his level. The Dodge dealer here has a good reputation, but I'm not going to have them rebuild anything. I felt they could find the problem the fastest & get electrical parts if needed. If it's something simple, then they can change out the fluid as well. Geez I hope it's something simple!

 

OK, let's really get into how to fix this one. 99% of this problem is due to the overdrive piston seals shrink and no apply to OD. With a quality scanner that shows data, not a crappy code reader blinking light deal. drive the vehicle. with it hot at say 45mph watch OD request. if it says on and no shift, you know the computer is commanding the solenoid. you can get into electrical troublshooting to verify wires and solenoid resistance. you can even bypass the computer and manually control the solenoid electrically.

I install a pressure gauge on the OD port, drive the vehicle on a hoist, watch my scanner for command and watch my pressure gauge. If I see a flutter 5psi or so, I know the seals are junk. In about 2hrs I can pull the OD unit, get new seals from the dodge dealer (under $10) and toss them in (you gotta be careful on this part). put the OD unit back in and viola it works again.

I've had 3 of my highschool kids do this diagnosis and repair... one was my gen1 cummins, one on my dakota and one on a students 4x4 dakota.

as for lockup. I have ONLY seen a non-lockup 518 on cummins only. every one of my overdrives have had a lockup (A500 and A518 except early diesel... my 99 cummins does have lockup)

 

I double-checked myself in the '90 factory service manual: the '90 A518 does NOT have lockup. I have no idea why, but it doesn't.

 

yep, I confirmed that too. 1990 A518 does NOT have lockup I went out and looked at a 1990 maxivan I've got. I know my 1994 5.9 does. but still this bit of useless information has NO value to the 4th gear issue.

 

Here's the latest..........
Dodge says they believe the problem is in the wiring somewhere. The OD selenoid is working he says, but the computer does not seem to give a message to shift to 4th. As a side note the cruise only works for about 10 minutes, then drops speed, picks up speed, then shuts off after a few times of that. So my worry is replacing the computer, at what cost. Should I try to find one from the wrecking or let Dodge find a rebuilt computer? Someone before us had been messing with the wiring on this van. I'm hoping it doesn't become a nightmare.