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Discussion Starter #1
I have a 2002 e320 with around 170,000 miles on it. Last week, it went into LIMP mode and wouldn't shift out of 1st gear. Took it to Auto Zone for a diagnostic, and it kicked out code p0702, so I took it to a shop yesterday that services import cars.

According to the mechanic, transmission fluid got into the transmission computer and wire harness (?) and it's stopped communicating with the engine.

I have two options according to them:

1 - They can pull the computer and harness and give everything a deep cleaning, blowing out and drying out as much of the fluid as possible, put it all back together and see if that fixes the problem. Quoted around $600 for this option.

2 - If #1 doesn't work, or if I don't want to gamble it, I can have them replace the harnessing for around $2800 and then I'd have to send it to a dealership to replace the computer for around $1250 plus labor. He said that Mercedes wouldn't sell the computer to them or anyone for that matter, and they "marry" the computer to the car, so it's not an option to buy a salvaged transmission computer and harness and replace.

I'd love to hear anyone's thoughts on the pricing and the problem. I see the transmission computer module available on salvage site and on eBay, which seems puzzling it if wouldn't do you any good without a dealership's involvement.

Thanks in advance for any insight, opinions or thoughts!

Dude
 

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1999 E55, 2001 E320, 1990 560 SEC, 2004 ML350, 2001 ML55, 1995 S500, 1998 SL500, 2010 E550 Sport zoo
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Let me be clear - with the help of the "stickies" at the top of this forum, and forum search - you should be able to repair this problem for under $50.

The "problem" the original tranny adapter plug in the transmission leaks internally (inside the plug) then that causes transmission fluid leaking there to "wick" up the harness into the transmission control module in the engine compartment. The small metallic pieces in the transmission fluid then cause communication problems - those communication problems are both in the plug end, and yes a "contaminated" transmission control board in the engine compartment.

Over 90% of the time this can be easily fixed.

1) Buy a MB transmission adapter plug - from the dealer is shoudl be around $35 (they stock them) - the same MB plug is sold by Chrysler/Mopar at a Chrusler dealer or on amazon for like $14

2) Buy a can of MAF spray cleaner from a retail auto parts store for like $9

3) Have a good flashlight for the TCM work

4) In the sitckies follow the pictoral instructions on replacing the tranny pug at the tranny. Do NOT overtighten the bolt when putting the new plug in - this is the only key issue here

5) use forum search to find a pictoral post on how to remove the TCM board in the engine department.

6) With board in hand you use the MAF spray to clean the board - you hold on edge and spray liberally so the MAF cleaner runs off the contamination off the board. Use up to 3/4 of a can that way. Free flowing MAF spray on the board does the work. You can air dry the board, doesn't improve much if you use canned air to dry it.

7) The liberally spray the connector inside the TCM housing to clear that contamination as well - there a bit of air to dry/clear that connector can help things a bit.

8) Any pre-existing codes will need to be reset.

Now - to you does that sound like $600 worth of work ? Run away from that shop - a quality independent would charge you $35 for the plug + 1 hr shop time to replace the plug + 1 hr shop time to pull and clean the board + $10 materials for the spray cleaner _ $75-$100 to reset the codes = but that same shop would say this "might not work so not guarentee's - but good chance this will work".
 

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^^^ Agreed.


Just to make it clear. you need about $50-$75 worth of parts.


You DO not need a new wiring harness.

You Do not need a new transmission computer.


You DO need the connector discussed it the previous topic, and one can of MAF cleaner (its a special cleaner) and a few quarts of fluid.

That's all the parts you need, I promise you that.
 

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Discussion Starter #4
Thank you both for your input. I'm planning on picking up the car and giving this a shot on my own - don't have a ton of experience with this type of stuff, but with the help from the DIY (pictures), it seems like something I can do if I just take my time and follow directions.

The two things I'm not sure about and I'm currently searching on are:

1 - Resetting the codes. Not really sure what is entailed with this or even what codes are being referred to.

2 - Adding transmission fluid. Seems easy enough, but was thinking that I needed a special tool to measure the levels.

Again, you've both been very helpful and I appreciate your input and time.

Thanks,

Dude
 

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2001 E320 - Brilliant Silver/Ash: 107,000+
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1) You need a sophisticated scanner to reset the transmission code(s). The dealers use the Star Xentry but there are others capable of this found at good MB shops.

2) Add any necessary transmission fluid through the dipstick tube. To properly measure the level, you need a dipstick tool, gotten from member ohlord, ebay, or a dealer.

You'll need to break off the lock pin on the dipstick tube. For a couple of dollars you can buy another one, dealer or probably ebay.

Good luck.
 
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