bobbyg

hello all just got my 1st benz, and after taking it to the car wash, my mil came on. went by autozone and pulld code p0702/trans control system/electrical. any help is and will be greatly appreciated.
i have a 2000 s500

chibenz

First welcome to mbworld. You are at the right place don't worry, I had the same problem as yours with code p0702. I went to few places but everyone had different opinion. Dealer asked almost $200 just to diagnose but then i went to my indy he pulled the code and told me that its a bad battery, he changed the battery and problem gone. So careful before doing anything else and spend money,change your battery. You can get it under hundred dollar from walmart store. I dont know your location but you can always called MB road side assistance and they will come to you and will change it. I am also giving you link with similar problem with another member.

https://mbworld.org/forums/c-class-w...nt-fooled.html

Good luck and update us.

bobbyg

thanx for ur reply and help chibenz.. i will go change the battery asap & let u know.
i appreciate the welcome as well & look forward to interacting with all the fellow MB owners.

tusabes

dont go spending money on a battery just yet.... because the error happened as soon as you went into carwash, something just got wet.

First take the car on a good long drive, 20-30 miles. Then disconnect the battery, get a hair dryer, and dry everything in the car esp in the trunk and in the engine compartment where all the electronics are Reconnect battery.

bobbyg

ok guys went and changed out the battery, mil went off then lit up again. the summer mode/winter mode button still dosent change as well as the auto/ manual stick...& its still in 2nd gear/limp mode.
drove it over the weeknd and dried out the trunk area and engine compartment really well, and the same issues remain. when i have her in gear i hear a funny noise like a train horn but on a smaller scale... something like choooo
i did use a obdII to read and reset mil light.

Ifari

After pulling the code,did you have it erased?
If not, do so and your problem may clear up seeing as you've changed the battery.

my06clk

Bobby.

Your TCM (Transmission Control Module ) is located uner the carpet of your passenger footwell. Check there for water damage. Also have a look at this link as it addresses cleaning the rain vents.
https://mbworld.org/forums/s-class-w...ins-clean.html.
THis is a major issue with these cars and the major cause of getting water into the cabin. If you bought this vehicle used, there is a chance these vents are clogged and you are getting water into your cabin.

If your TCM is fried you have to get it repaced and reprogrammed. A fried TCM will cause the symptoms you described.

bobbyg

thanx u ifari for the note... as i did erase the code and reset the mil light after switching out the battery. so i will now read up on the report of water leaking into the cabin and the plugging up of the vents, thanx u myclk06... i just finished checking the vent and its free and clear of debris... i looked at the pssnger side footwell.. no water spots in view. not sure under the carpet though. in the rear of the car i do see water spot areas on the pssnger side as if water leaked/dripped down from the light area.there is 1 bulb out in the ceiling rear pssngr mirror . is that why i always hear my seats clicking? as if there is a short in the unit under the rear seat? could that have an effect on the tcm module under the front pssnger carpet?

chibenz

you mentioned that you erased code by using obdII scanner. Well if its generic scanner it will not fix the problem, even if you erase the code it will come back. You have to erase it using Mercedes benz diagnostic tool. Ask your local garage shops if they have mb software to reset and erase the code.
Good luck.

bobbyg

thanx chibenz guess im going to have to stop at the local shop to see if they can use the mercedes computer to reset..
i'll let u know...

bobbyg

ok took the s500 to the dealer this week they did diagnostic and said my connector on the side of tranny was leaking had them change it out... also the rep told me my tcm was shot... said it was 2 hard codes in there, and until i swapped tcm the cel would stay lit and car will not come out of limp mode. any suggestions not sure if hes being 100 honest with me.???
also after he wouldnt clear the cel i went to autozone borrowed the obd2 and cleared it out myself. still in limp mode... grrrr so i guess i will have to try and clean the tcm or swap it out $800.00
or should i take it somewhere and let them use the star tool to reset? any suggestions mb family?
still cant switch from winter to summer mode also...

madcyborg

Hello all. I wanted to chime in and supply some information on what it took to fix my P0702 /safemode issue. It started out lock step like the rest on here. The car would not shift so turning the car off and then on would remedy the issue, frequency of the problem was not often. After I had the issue and could not fix it by pulling the battery, checking fuses etc I took my E-320 to Ken Garff in Salt Lake City Utah. Star assist determined my transmission control module was bad and boy was it bad... The mechanic accessed the module and found it had wicked transmission fluid and filled completey. Needless to say, the TCM was shot. A new module was installed , the dealer called to take my car home only to realize the problem was not yet fixed. I never left the lot. Additional work was done, due to heavy saturation the wiring harness was soaked in fluid as well, my harness was getting 4 volts... After a new TCM, and wiring harness that had to come from Stutgart my beloved pal 'Hans' has risen to road worthiness once again.

For those curious about dollar cost ... My bill was 3200 ish as the TCM was 1688 and the wiring harness was 500+ 10 hours shop time. 1600 - ish.

I hope none of you get this bif of a repair bill, usually its about 1700 for the TCM because the harness can be cleaned up and reused.


good luck all.

Rory Siwik

Krispher

Thanks very much,

So I had the same problem " Error code: P0702" and it's so unfortunate that I went to AutoZone also to get this reading. I just went to the express oil and services next door to AutoZone and the mechanics we're fully booked so I decided to go get my battery check over at AutoZone and it turns out I have a bad battery which I was a little awear of but they had only confirmed it. Then I asked the autozAut guy to do a engine light check and he stick his little meter reading device in the car then on to his computer, next thing the guy reading out the error code to and now am calling all the mechanics shops I know to ask about it. I got answers I wasn't prepared to handle so I came on here only to find similar issues, and I bet believe it's the bad battery probably why this error is coming up. I don't have the money to change the battery right now but I'll update on this matter as soon as I change my battery.

wallyp

Krispher,

First, it is a good idea to check the dates - the post that you replied to is dated 2010. We know more now about the problems than the folks did eight years ago. Most of the time, the "TCM full of ATF" problem can be cured for much less money. You can just pull it out and clean it with brake and parts cleaner. The fluid leak up the harness can be stopped with a very inexpensive, easily-installed transmission electrical plug.

In addition, this is the W220 (S-Class) Forum - you will get quicker and better answers for your questions and problems in the forum that covers the C240.

I would suggest that you will not be too happy getting your Mercedes repaired at express oil-type stores. You need to find an independent shop that is familiar with Mercedes vehicles and has the proper diagnostic equipment.