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My attempt at replacing the transmission plug.

167K views 158 replies 55 participants last post by  MBGraham 
#1 ·
This afternoon I went ahead and changed out my transmission harness plug/ connector, the how to's that are around for this are pretty good but I was still not sure going into it how to remove it so I decided to snap some pics of the process.

What the underside looked like, when I first jacked up the front end.


Pull down the wire connector (fastened with a clip) to reveal the screw that holds the shield in place.


There's a star pattern screw hidden away under that harness that I just pulled out of the way, unscrew it.


Once the bottom screw is removed, simply push the thin metal shield out of the way revealing the connector.


Better look at the connector.


Twist the plastic white tab towards the bottom as the arrow indicates. The twist motion pushes out the wire harness connector.


Once its released, pull it out the rest of the way, out of the way.


This is where the problem comes from... the oil leaking into the wires, as you can see its drenched in oil.


There is a 7mm bolt in the center of the connector where the arrow is pointed.


7mm setup to unscrew the bolt.


This will allow you to pull the connector assembly out, this is i the part you'll be replacing. Closer look at the connector you'll realize that you did not have to purchase the whole connector, rather just the two o-rings that go bad over time. The connector only cost $15 from the MB dealer, the o-rings would've been $1-$2, so not a huge savings there either. The o-rings I'm referring to are pointed out by the red arrows.


Once you pull out the connector, this is what you should end up with.


The old and the new connector.


The new connector in place, with the 7mm bolt tightened.


From then on, just work backwards. The whole process took less then 30 minutes. In my situation the transmission fluid is very dark and will be replaced here very soon.

Kruso
 
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#68 ·
The bolt stays in the adapter, it has a clip/keeper on it. Once you are sure it is loose, then simply remove the adapter; the bolt will come out with it.

BTW, please click user cp and edit details to add your vehicle and location to your profile, it's often useful information when you are seeking information.

Good luck.
 
#70 ·
When I get my car back on road, this is a job I will need to do (Found oil in TCM).

At 70something, I am getting less and less inclined to crawl under my cars. Any idea of the official MB shop time to change the seals? (In WIS, they say to just change seals, so I suspect that is what they do).

Any idea of what the official dealer hours are to re-seal the plug?
 
#72 ·
Dang. If I lived closer I'd come give you a hand. I think the gas would cost more than the shop time. Indeed, I'm sure of it.

I loaded up the WIS and looked it up, but I can't figure out how to configure the work units and get them to display.

I will say that it took me less than an hour, and that included raising the car, supporting it properly, doing the work, dropping the car and cleaning up. That said, it's impossible to get out of the dealer for under US$100, and I bet they will smack you with diagnostics and some other nonsense...and charge you retail plus for the part. Personally I'd buy the part (amazon ship up there?) and take it to an indie shop (or indie transmission shop) if you're not inclined to DIY.

If you have ramps, a floor jack and stands (raise the front once the tires are on the ramp to extend the suspension and give yourself more room), get it high enough you can mostly sit under it and it's a very easy job. Set all of your tools and the part and a little pie-pan to catch any fluid on top of a large piece of cardboard, then slide it under. Then you slide on it pretty easily as well (much better than trying to slide on concrete). Do the work, then slide out, then pull out the cardboard.

I'm attaching the WIS for the changeout, not that it really adds anything to the thread.

Good luck.
 

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#73 ·
Let's back up. Exactly what are you trying to do? For that matter, why not start a thread describing your symptoms and what you're doing, since we're clearly outside the bounds of this DIY thread anyway?

And *please* click user cp and edit details. Or at least post specifically what car you are working on. (It's the last time I'll ask; I'm not trying to be difficult, but it's common courtesy and requisite information...if you can't be bothered to do that, I won't feel compelled to take the time to help out anymore.)
 
#79 ·
If you roll the front tires up on 2x4 blocks, it is much easier to subsequently use a hydraulic jack to get to the center lift point, and jack the car in one action - then put the jackstands under the side lift points. Otherwise, there will not be enough "throw" for the handle. You don't have to remove the belly pan to access the transmission adapter plug. (which is much easier to access by sliding under the car from the front IMHO) Photo below is from my S430, but similar to the E420.
 

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#81 ·
I thank you all for your expertise. I was able to follow the directions and change mine out on my 1997 E420. I have a persisting problem that I could use advise on. My TCU was, like many of the pictures here, ATF contaminated. I carefully pulled the electronics out of the case and cleaned it thoroughly with electronic cleaner and the car remained in limp mode. I even bought a used TCU off of ebay and it worked well for a day but has gone into limp mode now as well.
What are my options? Can the TCU I got off of ebay be reprogrammed? Would that help me? What should I look for in terms of cost?
I know on newer cars the TCU is married to the car and a replacement must be programmed by the dealer (at least that is what I gather from reading) but is that the case for 97's?
 
#83 ·
Until and unless you clear the error codes out of the TCM that result from the fluid incursion, you will indeed have persistent problems. Buying a used one from Ebay doesn't mean it won't have errors stored in it as well.

In your shoes, I would reinstall the original TCM and then proceed to an indie or a good transmission shop that can plug in to the system and address the TCM properly to clear the codes. Regular garden-variety OBD-II code readers cannot do this.

If the codes thereafter return, then you likely have to replace the conductor plate, it's a fairly common issue for the earlier years of the 722.6xx transmission.

Good luck.
 
#82 · (Edited)
I ordered a transmission adapter on-line from these guys) along with some other parts. They have both OEM and URO types.



I ordered the OEM, but although some parts came in MB packaging, the adapter did not.



This worried me a bit, but the part does state it is Made in Germany and it is imprinted with the part number and a small MB star. Hopefully it is same as OE part. (The site says it is!)



I didn't check local Chrysler/MB dealers for this part seeing I had other parts coming. Price paid is not great but probably less than local.

Next step, is to check if in fact I have a leak (o-rings were replaced about 4 years ago by dealer) and then do job. Based on great write up by OP and other tips, seems like I may go under car myself :( Want to check the shift bushing while under there.
 
#84 · (Edited)
I am midway through this job (I hope!)

When I removed the exterior plug, there was some fluid, but not a great deal.

BUT, when I went to remove the adapter, I found that the 7mm bolt was already loose!

I recall the dealer changing 0-rings at some point. Maybe they couldn't get the bolt to catch?

I tried to tighten it (before removing the old adapter), but it would not catch.

I am concerned that whatever that screw threads into may be stripped.

Perhaps I could uses a slightly longer screw? Or maybe remove the old one from adapter and see if I can get it to screw in without the adapter present?

What does that screw thread into? Plastic or metal?

NOT TO WORRY.
I inserted a short bolt from the drive side of the 7mm socket so it would push on the bolt head while still gripping it. This allowed me to push on the bolt head. I did a trial run on the old one and it tightened up fine. Then installed the new one. It went it reasonably easy but I did lube it first.

Lost just over a litre of ATF, so need to top up tomorrow.

I have a feeling that all I really needed to have done, is tighten the original bolt.
 
#85 ·
MBGraham,
Your experience suggests to me that the socket is too large (read URO).

When I initially installed a URO part, it was very tight and I needed to use the center screw to pull it into position. Lasted 6 months before leaking after which I bought one from the dealer. That one fitted more gracefully and the screw was able to grab threads without pressure.

No leaks to date (12 months and counting). Fortunately, it looks like I didn't bugger the conductor plate.

Skippy
Skippy


Sent from phone.
 
#86 ·
Hi, Skippy. You're on a phone so it's easy to miss stuff (I do it all the time, too). But the plug he just replaced was the one that was odd, he said the one he replaced it with fit better, though he lubed it first. Since he ordered the OE and not URO part from his source, hopefully he's good.

Stay with it, MBGraham. Whatever the issue with the original one, I'm more comfortable that you replaced it.

Good luck.
 
#89 ·
Hello All,

Just received my shipment of fluid, gasket, filter[made in China no less], and the Uro adaptor. All is installed.

The Uro adaptor fit well, the o-rings seemed to engage the bore tightly. TNo issues with the 7mm bolt. The drain bolt to the pan would not budge, so I dropped the pan and drained the fluid that way. It was cocoa brown. The engine has logged 149K miles, it was time. So far it has only taken 3 liters of fluid. I'll do some short driving tomorrow and check with the dip stick. Everything is super clean. I'll monitor the adaptor and if it starts leaking, I'll swap it out for the Dodge part. As for the pan plug I'll take it to the MB shop and ask them to loosen it for me.

I'll be interested to see how well the adaptor holds out.

George
 
#91 ·
As far as I know conductor plates are sold only as whole units in US and you can not buy anything separately. I still have the plate that I am not sure was bad when I replaced it over a year ago. You are welcome to it if you think you can use it. PM me your address?
 
#92 ·
Well I just looked, the E320 was dry, but my E430 was very wet. Cleaned out the plug, case and circuit board. Off to a Dodge /Chrysler dealer for a plug. I also noticed my fluid was dark yellow, even though the fluid was changed about 40000 miles ago I guess I might as well do it again. Good thing I checked before any problems started.

Another great helpful thread. What did we ever do before the Internet?
 
#96 ·
Just dropped the pan, changed the filter and the transmission plug. Not that hard, I wish I had a lift though, it is getting harder to crawl under these as I get older.

My plug must have been leaking for a while. I put 3 quarts in, took it for a ride to warm everything up, then checked the level. It was 1quart low, after adding it was perfect. Most here say you need 3 quarts to do a filter change so mine must have been low.

The car fax I got with the car said the fluid and filter was changed at 50,000 miles. I doubt that though, the trans cap still had the black lock on it, and the fluid was BLACK. Now I am wondering about doing the flush after a few thousand miles of this new fluid.

Has anyone used their topsider oil pump to remove the trans fluid? I have one and it would make it easier to do just the comming fluid changes if I don't do the flush with the hose.
PHP:
 
#97 ·
A topsider with a sufficiently long and small enough diameter will get past the stops in the tube (see photo with suction tube hanging down), and net you about 2 Liters removed. Not efficient, but it is effective (and easier) than a bottom drain or Yummling flush when there is no torque converter drain.
 

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#98 ·
Hi Kurso. Thanks for posting these pictures. I am having difficulty in removing my TCM chip from its casing - is there a trick I'm missing?
 
#101 ·
Maybe ATF is spilt when topping up the box through the filler tube?

No, ATF amazingly makes it's way all the way up there into the TCM box, you gotta get it open and spray the heck out of it with MAF cleaner spray. Also spray the wire harness connector snaps on the TCM box. If the connector plug under the car is clean, this cleaning job should resolve a good number of issues.

Good luck.
 
#104 ·
Well, it shouldn't be surprising. Your DIY and the detailed pictures are excellent. I just checked my ECU box today after various issues on my car and found it flooded. Then searched and found this post, which lead the way to my getting into the nitty gritty quickly and efficiently. Great work and thanks to all who post their expertise and experience.
 
#105 ·
Transmission Connector

This is the best I have seen so far. I have seen some videos on youtube, but this step by step method is a lot more usefull.

quick question. Do the wires come out as one unit or will i need to insert them back one at at time and risk wiring it wrong?:):thumbsup:
 
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