518 OD not engaging

95 518 is no longer shifting into OD. Lock-up still works.
I have it wired with power to center pin and 2 separate toggle switches to ground for OD and LU.
When I hit toggle for OD, nothing happens, toggle for LU does work and RPMs drop 5%.

So is this most likely the solenoid?
What else can I do to troubleshoot to pin down the issue?
Are there 2 separate solenoid for OD & LU?

What's involved if it needs replaced?

Thx

Check for power to the solenoid.Yes there arer two solenoids.

How would I do that?
Single 12V input for both OD &LU
It has a 3-pin connector, 1 for power other 2 to provide ground for OD &_LU

one way would be to drop the pan, then apply power and ground to the connection on the case, then listen and feel for the solenoid[s] to activate.
that would be my first step.
if they both work at the transmission, i would then work backward in the harness to see where the connection breaks.
if the solenoid[s] does not work at the transmission case connection, i would then go directly to that solenoid with power and ground.
if it then works, the wiring to the case connector needs repaired.
if the solenoid doesn't work, it needs replaced.
just my way of doing things.
your mileage will vary.

check to be sure you still have a good ground it could be a bad switch. As to replacing the solenoids I found this which might help. https://www.2carpros.com/questions/dodge-ram-2001-dodge-ram-overdrive-solenoid.

That two pack can be removed without dropping valve body. My SnapOn box can activate each one to check if working. Around $70 and easy to change out, no need to take harness out just unplug at solenoids, put small wire ties back on, done.

What if the solenoid is good, what else could go bad?

What does the OD solenoid activate, is there a clutch pack or something, what changes the ratio?
I think the OD circuit was miswired so the OD was hardwired to ground.

Would it be possible to hear the solenoids activate through the pan, before it’s removed?

Appreciate the replies

I have never been able to hear them. You can remove the o/d ground, key on o/d switch on check for voltage at the ground wire. There should be voltage there. If not the solenoid or wire is open.

Check the resistance with an Ohmmeter on the Lockup side, record it, then do the OD side and compare. Should give you a good idea if the electrical side is working right...

The solinoid activates the valve with the big spring and piston in valve body, have to look at a diagram on internet. Once activated the overdrive clutch pac engages. That’s in the tail housing. If that’s gone major linning pieces in the pan

Well, now I'm worried, did the 2 tests mentioned above,

Disconnected all wiring so there is 12V to center pin and the 2 outside wires are not connected to anything.

1) measured resistance between center pin, and it's 36ohms for both LU and OD.
2) feed 12V to center pin, measured LU and OD side to ground, they are both 12V.

So that seems to indicated that both solenoids are ok?
Did a google search and it looks like solenoids are basically a coil winding and should be a DC short.

So unless the other side, magnetic plunger in the solenoid is bad, I've got bigger issues.

Did you try to see if you had OD pressure? Report back your findings.

If the solenoid is truly good, first thing to look for is a stuck OD control valve, which lies underneath that solenoid.

Oops, misread OP.

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I don't have a pressure gauge, but I know it must put out 50lbs around 50mph.
My home brew controller has a pressure switch that activates at 50mph, LU still works, the OD just isn't kicking in.

I took car for a test run, for another issue I'm chasing, and tested both the LU and OD with the manual switches (only above 50mph)
Randomly toggling the OD switch and it did kick in (1 time) and the RPMs dropped as expected and ran fine until I had to stop for light.
OD never came back on, but LU always works.

So at this point I'm thinking my next step is to just bite the bullet and attempt to change the solenoid.
Any other options?

Any harm in driving it as is, and just use the LU above 50mph?

Thx

Additional bit of info, random or related, no idea?
I just swapped in a new motor that took me a year to get finished.
It's seems like forever ago, but OD worked before I started the engine swap.
But it's hard to remember, and most of my driving probably didn't require OD.
This transmission was a JY pull 7 years ago, and was completely rebuilt with Transgo shift kit.
It has run flawless for the last 7 years, and only has 15k miles on it since then.

So the transmission has been sitting (in car, in garage) for 1 year, and just randomly craps out when I take car out for first test drive with new engine........................

I don't have a pressure gauge, but I know it must put out 50lbs around 50mph.
My home brew controller has a pressure switch that activates at 50mph, LU still works, the OD just isn't kicking in.

I took car for a test run, for another issue I'm chasing, and tested both the LU and OD with the manual switches (only above 50mph)
Randomly toggling the OD switch and it did kick in (1 time) and the RPMs dropped as expected and ran fine until I had to stop for light.
OD never came back on, but LU always works.

So at this point I'm thinking my next step is to just bite the bullet and attempt to change the solenoid.
Any other options?

Any harm in driving it as is, and just use the LU above 50mph?

Thx

Driving in third with or w/o lockup will not hurt it a bit. The fact you got o/d makes me think a band solenoid.
But could be several things.

Setting for a long time shouldn’t have an impact on it.
Driver side pressure tap above rear cooler line is O/D pressure tap. The one on the pass. side is governor. You should have no more than 5 psi until O/D is activated.
You mention 50 psi. You may be reading the gov psi - that follows road speed.

[/quote]

Looks like only 2 manufacturers for the solenoid.
Any thoughts on which might be better, seems like a simple part, curious why ATP is 2x the cost

ATP for $60
Sonnax/Rostra for $30

Have you checked what the dealer has for OE Mopar solenoids?

What I would do too, there’s a reason for low price

Factory part is long discontinued

I’ve been away from Inside Chrysler since December ‘16.

If I recall the OE for the solenoid was selling them to Sonnax. But don’t hold me to that. Rostra regularly copied our designs.

I ordered a new solenoid and removed the tranny pan.
Issue was the LU worked but OD doesn't.
Before replacing the solenoid, I wanted to try 1 more thing.
I have manual toggle switches to enable those lines (separately) to ground.
So I tried toggling both switches, with power applied, did this while under car with finger on each solenoid.
I expected to hear or feel the LU side doing something? But nothing happened for either side.
Am I missing something?

No, I've never heard or felt anything in those solenoids.

Appreciate the response,
So is there anything I can check before replacing this solenoid and dumping $100 worth of fluid in it?

You could clean a drain pan, clean the trans and save the fluid to reuse. Other than that, I know of nothing.

Bench test the solenoid.

How would I do that, looking at it, it doesn't seem to have a plunger.
I'm thinking the coil is energized when voltage is applied to create a magnetic field to hold something in the tranny?
No moving parts on this solenoid, that I can see.

Check your PM

Well I guess I should have taken a closer look at the pan before I committed to replacing the solenoid.
So there's grey sludge, material on the magnet, and a couple pieces of metal.
What am I looking at, and is this the reason the OD didn't work?

With the Chia pet for a magnet, it’s time to get it apart.

Likely the OD unit is failing. Just a guess at thins point but likely one of the large needle bearing units or a planetary starting to fail.
The most common failure we saw in the Reman program was the bearing on the back of the main case - the OD thrust bearing.
And when it fails you lose the required travel to apply the OD clutch and disengage the Direct clutch.

So, um... If that is what actually made the OD not function, and a guy kept driving it without the functioning OD, is it more costly to rebuild the trans then if it was pulled and rebuilt right after the OD quit working?

I blew a trans cooler line but didn't know it until ran it out of fluid and I coasted into a parking lot. I repaired the cooler line, added 8 quarts of ATF 4 (96 46RE 4x4 trans with 44K miles). The trans seemed to work OK except the OD didn't work. After nearly a year of using the trans, it doesn't seem quite right when leaving a stop light (I might be getting paranoid). Once its moving it seems OK, except the no OD. It shifts very smoothly from 2nd to 3rd.

I'm expecting to have to rebuild the trans (I'm hoping to make it to spring). I could drop the pan if you think it would be helpful, but at this point I suspect the damage is done and a fluid, filter, and maybe a few parts won't help long term. I'm probably going to run it until it fails, or spring, whichever comes 1st, unless you think a new filter and fluid will help. Should I plan on rebuilding a different trans, or is this one going to be OK to rebuild?

No telling until you get it out. Is this the same trans that had water in it? If so just yank it.

Hard to tell from the pics but those pieces appear to be friction material or maybe snap ring pieces. The gray sludge is probably aluminum from the torque converter or rear support. Time to go through it.

All just guesses at this point.

The snap ring is likely the wave snap ring for the OD clutch. Regardless, with the debris is needs to be gone through.

Appreciate the replies, this is really frustrating.
Paid $1k 8 years ago to have this "completely" rebuilt, as a carry in.
Only 15k miles on it since that time.

So I guess I need to pull it and carry in to someone else.
What do I tell them or ask for during the rebuild to make sure it gets done right this time?

Thx

PM sent.

If there’s pieces it’s broke. Time to come apart, think of all the sludge-pieces going thru the trans now. My guess is the OD thrust bearing

Nope. The one that got the water in it got replaced, I bought a brand new 2010 Mopar trans from a guy that bought it to put into a project he didn't use, it was sitting on a shelf and still had the factory caps on it I bought it for about the same money used transmissions were going for. Got that put in the truck and sold the truck.

This one is in my 49 on the Dakota 4x4 chassis. Had 44K miles on it when the truck was built. I've driven it about 3500 miles before the Dakota radiator started leaking between the aluminum core and the plastic tank last Dec. I bought an aftermarket radiator (that fit in this truck much better). I watched for any issues for a couple weeks, but about a month later while going across town, one of the cooler hoses blew off and ran it out of fluid. I had no idea why it started slipping about a block from where I could get off the road. As soon as I opened the door I knew what was going on. There was an auto parts store right across the street from where I stopped. I was able to put the cooler line back on, and then added 8 quarts of AFT+4. The drive home seemed fine, but a couple days later I noticed the OD wasn't working on the highway. A few weeks later I noticed it seemed a bit sluggish leaving a traffic light, but seemed to up shift 2-3 (very smooth) OK, the truck spends most of its time in town, so it wasn't a big deal not having the OD, at the time. I've considered dropping the pan adjusting the bands, change the filter, and give it a look over inside, but I'm concerned about what I might find inside the pan. It would be a major issue pulling it to rebuild it right now. No hoist available, I'd be doing it on jack stands on my back. I'm not sure I can get the truck high enough to get that heavy pig out from under the truck. The hoist is suppose to be available in the spring. The only trans rebuild shop I'd begin to trust has a 2 month backlog. Thoughts or suggestions?

Replacing the filter and adjusting the bands won't help the no O/D situation. I would do some electrical diagnosis before anything else.

other than the od unit, those transmissions are like a 727.
if it were me [and in time, it will be] i would get an ATSG service manual [ i have one for the A518 and one for the A500] and a FSM for whatever year your transmission came from. [i also have one of those]
also, get the monroe book. that has very good tricks and tips in it.
then, i would obtain a good core, [i have already obtained two] rebuild it over the winter, then install it in the spring.
if you have rebuilt a 727, you can do an A518.
this is just me speaking from my personal experience over 55+ years of playing with this brand.
i'm still stupid, and i still ask questions because i either forgot or never knew stuff in the first place.
your mileage will vary.

So my trans is a 1996 46 re. I have available a 92 46 rh (?) available in unknown condition. I'm running the 96 EFI and computer, can the hydraulic OD be converted to the electric, or will the 96 computer not have a problem with the older trans? I can pick the hydraulic OD up cheap, then have it rebuilt and waiting.

To clarify my sluggish stop light acceleration, back before the fluid dump, I could fry the tire (open rear) leaving a dead stop. Now it won't spin at all, but moves the truck well after the first 10' or so. Both the acceleration issue and the loss of OD both were noticed after the fluid dump, the stop light thing right off. Dropping the trans pan is a $145+ for material only experience these days, if it would help, I'd do it, but if it won't help I'd rather put that money towards the rebuild.

I’ve had my 2001 trans in and out 5 times, left an o-ring out the first time for the lock up, burnt the front clutch out. The trans is more complicated than the reg 727 mainly in the VB and OD. The clearances in the OD have to be spot on and measuring that takes special tools (made mine) the OD also takes a big press to service the spring and clutches, once out replace spragg and Torrington bearings. I can do one now real good but it was a learning experience (I could do the 727 blind folded) best leave it to someone you KNOW is good with these trans.

The short answer is no, the 96 PCM will not work the 92 trans. Maybe someone has done it with a flash program but I would have no idea how. The O/D and L/U work the same on the RE as the RH but the RE has no hydraulic governor and the RH does.

cudaman and geetar are correct. i guess it depends on how comfortable a guy is tearing into these things, plus having the necessary tools to do so. which i completely forgot to mention !
i guess in Gene's case, it would probably be best to have someone who knows the ins and outs of these transmissions, do the job.
it's too bad you aren't [lots] closer. there is a guy down by the Pittsburgh airport that is VERY good with these transmissions.

They really aren't that complicated. The 727 is probably the simplest auto trans there is, part of what makes them so reliable. The 518 is basically the same with a compounder added to the back of it. If you have a press with a little ingenuity and fabrication you can get the O/D portion apart. I once used a floor jack and my steel work bench to get one apart. It looked pretty sketchy but it worked. Of course the tools are available and probably don't cost that much.

Well, the last 727 I rebuilt was back around 1990. Someone else is going to rebuild the trans for me. Its $1200 at the local guy, if I carry it in and carry it back out, and he was backed up at least 6 weeks a few months ago. I can get a remanufactured trans from a national chain for $1500, dropped off at my door in about a week, that has a 3 year warranty (the local guy has 1 year). Still not looking forward to pulling this pig out (its a 4x4 truck), sure hope my buddy gets his hoist up and running by the time I need it.