P0123 Code when accelerator pedal reaches kickdown
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Joined: Jul 2020
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From: Pullman, WA
2003 ML350
P0123 Code when accelerator pedal reaches kickdown
I realize that this has been posted before (https://mbworld.org/forums/m-class-w...s-power-2.html) but it didn't look like they ever figured out what the problem was.
My car: 2003 ML350 W163.
My problem: acceleration works fine until I get to kickdown switch. After engaging kickdown switch, half of the time I lose power and the car goes into limp mode. After restarting the car, everything works fine. My _generic_ code scanner pulls p0123 and so does the Oreilly's scanner. My accelerator pedal is wobbly from left to right so I am planning on replacing the pedal and I am thinking of replacing the actual kickdown switch. Does anyone have a suggestion on how I should approach this problem? I am thinking of purchasing a Mercedes specific scanner to help diagnose issues with the car. Does anyone have recommendations for the W163?
My car: 2003 ML350 W163.
My problem: acceleration works fine until I get to kickdown switch. After engaging kickdown switch, half of the time I lose power and the car goes into limp mode. After restarting the car, everything works fine. My _generic_ code scanner pulls p0123 and so does the Oreilly's scanner. My accelerator pedal is wobbly from left to right so I am planning on replacing the pedal and I am thinking of replacing the actual kickdown switch. Does anyone have a suggestion on how I should approach this problem? I am thinking of purchasing a Mercedes specific scanner to help diagnose issues with the car. Does anyone have recommendations for the W163?
Thread Starter
Junior Member
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From: Pullman, WA
2003 ML350
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From: Bronx, N.Y.
2002 ML 320 & 2006 ML500
Last edited by Maj. Dundee; Apr 4, 2021 at 05:46 AM.
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2002 ML 320 & 2006 ML500
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Thread Starter
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From: Pullman, WA
2003 ML350
So I have some trouble with not being able to source two of the parts... These is what I heard from Pelican Parts.
Does the replacement part 000000-003648-MBZ work for this application?
I also got another email for the stop...
I am looking for another source to purchase this. Does anyone have any ideas for another retailer?
Spoiler
I also got another email for the stop...
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MBWorld Fanatic!
Joined: Oct 2011
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From: Bronx, N.Y.
2002 ML 320 & 2006 ML500
Thread Starter
Junior Member
Joined: Jul 2020
Posts: 42
Likes: 5
From: Pullman, WA
2003 ML350
Last edited by zer0pwn; Apr 24, 2021 at 06:58 PM.
Thread Starter
Junior Member
Joined: Jul 2020
Posts: 42
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From: Pullman, WA
2003 ML350
Hi Maj. Dundee, the question was unnecessary on second glance. I am assuming it is just a mechanical stop that prevents the pedal from travelling any further and damaging the cable. I was hoping the problem was the kickdown switch as I can easily source it and the code was related to a high voltage detected on the TPS. Do you think the kickdown switch needs to be replaced or should I continue with the plan you outlined? I am still working on sourcing the stop and having a tough time. I appreciate all the help
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Joined: Oct 2011
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From: Bronx, N.Y.
2002 ML 320 & 2006 ML500
Hi Maj. Dundee, the question was unnecessary on second glance. I am assuming it is just a mechanical stop that prevents the pedal from travelling any further and damaging the cable. I was hoping the problem was the kickdown switch as I can easily source it and the code was related to a high voltage detected on the TPS. Do you think the kickdown switch needs to be replaced or should I continue with the plan you outlined? I am still working on sourcing the stop and having a tough time. I appreciate all the help
Do you have a bump under the gas pedal? As of 2003 MLs, they did not have a kick down switch.
Last edited by Maj. Dundee; Apr 25, 2021 at 01:55 AM.
Thread Starter
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From: Pullman, WA
2003 ML350
In the diagram you posted for the parts I needed, it listed 1 accelerator pedal, 2 hexagon head bolts, and 1 end stop. I am talking about the end stop part number A 163 301 00 41.
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From: Pullman, WA
2003 ML350
Hi Maj. Dundee, there is a bump/kickdown switch under the accelerator pedal which is why I was really confused (two parts were going to the same spot from what I could see from the diagrams). I can press it and feel it when I push the pedal to the floor. I can get a picture tomorrow if necessary. It is weird as I do see the documentation you provided that shows it shouldn't be installed after July 2002.
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Did it ever work before?
Here is a used one on ebay.
https://www.ebay.com/itm/35310466169...Cclp%3A2334524
Here is a used one on ebay.
https://www.ebay.com/itm/35310466169...Cclp%3A2334524
Last edited by Maj. Dundee; Apr 25, 2021 at 06:42 AM.
Thread Starter
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From: Pullman, WA
2003 ML350
I have replaced the accelerator pedal and the kickdown switch but now it is seeming worse than before. I cannot get the switch to kickdown at all. The vehicle seems like it is starting to go into a lower gear and then just stops and goes into limp mode. It may be possible I got a bad kickdown switch so I will try putting the old one back in and see if if it will kick down. The kickdown switch worked before but it was hit or miss. About 50% of the time it would go into limp mode. After replacing the kickdown switch I haven't been able to get it to kickdown once. I tried disconnecting the new one and reinstalling it to rule out a loose connection but it still isn't working. So I will try putting the old one back in.
Did it ever work before?
Here is a used one on ebay.
https://www.ebay.com/itm/35310466169...Cclp%3A2334524
Here is a used one on ebay.
https://www.ebay.com/itm/35310466169...Cclp%3A2334524
Thread Starter
Junior Member
Joined: Jul 2020
Posts: 42
Likes: 5
From: Pullman, WA
2003 ML350
Old kickdown switch is back in and seems to be working 100% of the time now. Maybe it was a loose connection or it was the accelerator pedal that was replaced. I am hesitant to say it’s fixed but it is looking good as I would be able to consistently get it to fail before. I will keep an eye on it and test it regularly and let you guys know the results.
I have replaced the accelerator pedal and the kickdown switch but now it is seeming worse than before. I cannot get the switch to kickdown at all. The vehicle seems like it is starting to go into a lower gear and then just stops and goes into limp mode. It may be possible I got a bad kickdown switch so I will try putting the old one back in and see if if it will kick down. The kickdown switch worked before but it was hit or miss. About 50% of the time it would go into limp mode. After replacing the kickdown switch I haven't been able to get it to kickdown once. I tried disconnecting the new one and reinstalling it to rule out a loose connection but it still isn't working. So I will try putting the old one back in.
Last edited by zer0pwn; May 10, 2021 at 03:32 PM.
Thread Starter
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From: Pullman, WA
2003 ML350
Well I spoke too soon, because the old switch started doing the same thing as the new one and not kicking down at all. Any ideas for next steps? Should I start looking at replacing the throttle position sensor?
Thread Starter
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From: Pullman, WA
2003 ML350
This was the fix. To help others, the solution was that I adjusted the new kickdown switch a notch higher than the lowest position by turning the button 45 degrees counter clockwise and pulling up by the black post, NOT the gray button. There are some gradations on the black post where you can see some kind of notches. I don't have a picture but you should be able to figure it out by experimenting with it a little bit. You then set it by rotating it clockwise by 45 degrees. You will know you are not in a notch if it won't set. I had to adjust mine higher than the lowest position to get it to work. I have not had any issues since this fix.
