W210 722.6: is there anyway to reset transmission codes without multiplexers?
 

My multiplexer is on the way but after some repair work my trans is in limp mode.

Is there any other way to reset the codes?

Anyone in northern Colorado want a six pack of beer?

Thanks

From what I recall, if the fault is fixed limp mode will clear at the next key cycle.

What sort of repairs did you do?

You'll need someone with the STAR system to reset the codes, or higher end aftermarket.

STORED fault codes won't put the transmission in limp mode, CURRENT codes will. There's still a problem......

Thanks for the replies. The only repair I did was to replace the electrical plug on the transmission. I had thought that it may had not been seated all the way when I first turned the car on, causing a fault code.

The way I understood it is that once a limp home mode code is activated, it must be cleared before it is released. Ie: Conductor plate fails.

Think of it this way. Let's say there's an intermittent speed sensor/conductor plate issue, right? The fault occurs momentarily then corrects itself, ok? The transmission will go into limp mode. If the problem isn't currently present at the next key cycle the transmission works normally again until the fault re-occurs.

This makes sense from a design standpoint. It wouldn't make sense to disable the vehicle because of an intermittent problem and FWIW this is a very common scenario. Hope this explanation helps :)

I'm wondering if the new connector isn't seated correctly. This is the one variable that was changed.

I checked the tcm and everything was dry and nice. Is there some pins I can look for resistance at?

What codes were you getting prior to any work?

Don't let this repair turn into a random replacing of parts.

Agreed, I know some troubleshooting is better than throwing parts. I don't remember the exact codes but it was a rather large list of all trans related codes. This is coming from 0 codes just prior. I'm going to pull the codes again tomorrow and remove the connector and inspect the pins

Is correlation causation?

No answer but after confirming proper fitment once again today for the connector, code po715 is present.

I had no signs of this part failing before connector replacement, that I knew of. Are there any signs?

Next step appears to be the conductor plate.

In the interest of those searching in the future I will update this.

I now have a working transmission. I also had the opportunity to replace the parking lever seal and the spring in the valve body, which had been in 3 pieces. Improvement but it never shifted that bad, surprisingly. Also replaced the conductor plate. I don't think it was necessary from what I found later but at this point with where I was on the project I saw it as preventitive maintenence.

To recap this began when I replaced the trans elec input plug. Trans immediately went into hard limp mode, clearing codes (via 38 pin socket) wouldn't resolve. Remove connector again and find a wire disconnected from its pin. This wire was about 2inches shorter than the others and the plug I removed had the 2nd update color o-rings which leads me to believe that I disturbed a improperly fixed mistake from my cars previous life. This harness will be replaced. New extension soldered/shrink wrapped and the trans is now mechanically fixed.

Still in limp home mode. Purchase car soft 7.4 multiplexer and usb to serial converter. Edit the characteristics of the comm port and clear the code with carsoft. The stored codes all related to the speed sensor, which in this case was a false reading to the conductor plate due to the damaged wire hiding under the cap of the elec connector. Car is no longer in limp mode and shifts perfectly.

This was my experience fwiw

I have a 1978 300 D radiator is bad and I am having trouble finding a replacement. Can I convert to a newer style with expansion tanks? Or any opptions that could sve money.

Thank you

^^^^

Very good advice.

When my w210 went into limp mode (due to coffee spill on the shifter) the only was to reset was with MB software. The shifter box was replaced and all methods to reset failed until dealer reset the code.