Hi,

First of all forgive me for asking a question which is not related to Mercedes Benz Vehicle, however, my car has mercedes benz automatic gear box, ie, 722.6 which is giving me a big problem and my mechanic has not been able to fix it in 1 year.

The reasons are lack of skill and lack of spares. Let me narrate the story.

My car is Ssangyong Kyron which has mercedes Benz gearbox 722.6.

Two years ago, during a river crossing, some water got ingested into the engine and engine overhaul was performed.

The mechanic decided to drain the ATF and put another ATF which was not the specified ATF for this transmission. It had a very hard shift and there was no change of gears. We later found out that TCU/TCM (transmission control unit) and TCCU (control unit for 4WD)

We replaced both. The vehicle drove fine for few months, even with non recommended ATF. However, one fine day, it did not move. We towed it back to workshop.

They checked the shift solenoids and found one of them faulty and replaced it. Had to wait 2 months to get it sourced from Korea.

The vehicle did move but after driving for a while. We experienced the following.

1. There is a jerk when shifting from 3-4.
2. It gave gear ratio errors like P2500 and P2503.

So we bought 6 new solenoids, new electronic plate, new ATF filter. However, the guy sending the spares sent the wrong ATF again, But we decided to try on it.

Now the car does move again but we are back to square one.

1. Whenever we put transmission to Drive (D mode), it shifts from 1-2, 2-3, and 3-4 has jerk and after that when we press accelerator the car goes momentary into neutral and then again into gear and we get the infamous P2500 code.

2. Whenever we put transmission to Manual (M mode) and select up to 3, and press the accelerator, it gives out P2503 code.

We have checked the continuity and harness upto TCU/TCM. The TCU/TCM is not contaminated. We do have a dipstick to check the oil level.

We are scratching our head as we do not have much knowledge of automatic transmission and we are just shooting at dark based on the codes derived from the scanner.

I would appreciate if anyone would point us towards right direction.

 

P2503 gear comparison is negative or the target gear is not reached.
P2500 transmission has an impermissible transmission ratio.

“Consider” complete valve body replacement & correct ATF. See attachment for an understanding of wear areas.

See here: http://www.sonnax.com/valve_body_layouts
Replacement click on 722.6
Rebuild click on Mercedes 722.6 valve body layout – click on part #s 10 & 11a

 

Thank you konigstiger,

I will consider this and will find ways to get sonnax parts or new valve body. One thing that I would like to tell you is that car has run only 30,000 km and it was on wrong ATF for just last 2000 km. Do you think, the valves got worn in just 2000 km of wrong oil?

valve body part number 211 270 00 06
conductor plate part number 140 270 11 61

 

I got a new valve body. Vehicle drove fine for 500 kms. Unfortunately, the oil pump broke and the new valve body got metal shavings and I think the metal shavings got into control sleeves and maybe they have worn out. I am getting P2503 again.

The car tries to go to 4th gear but falls back to 3rd. In scanner I see, target gear 4 but actual gear is 3. Maybe the control sleeve is not able to hold the hydraulic fluid and its leaking.

 

Maybe ur TCU got wet. Anyhow, what battery u using?

 

Hello

What’s the end of the story?
I got same problem in my Grand Cherokee 2.7
I’ve changed oil, filter, and wiring in gearbox.
Have you solve the problem by replacing the valve body and oil pump in gearbox?

 

The car got solved by replacing the 3-4 control overlap sleeve made by Sonax.

However after few months, the car had an accident and its front left wheel hub got damaged and needed replacement. The gear lever that runs from selector to the transmission also got a little bent. Now we have replaced the front wheel hub and straightened the gear lever. Now the car runs fine except it does not go into 5th gear. I get a code "P2503".

I have tried in D mode and manual mode. It simply does not go into 5th. I checked wheel speed sensors with computer and they are all working fine. When checking with computer we found that instead of going to 5th from 4th it tries to go 3rd but again gets back to 4th.

In manual mode, when we select 5th gear, it displays 5th gear in the instrument panel but in the computer it shows D. In the same test, if we select 4th gear, it displays 4th in instrument panel and shows 4th in computer tool.

I checked all solenoids in valve body, checked the all control overlap sleeves, they are fine. What could be the problem?

 

I already solved my problem by replacing whole valve body from second-hand gearbox.
It works fine since December.
I guess this transmissions don't like water.
Thanks for reply anway.