Transmission let go at freeway speeds (P0700 and 720)
Thread Starter
Member
Joined: Jul 2006
Posts: 193
Likes: 7
From: Alameda, CA
1991 SC Miata, 1999 W210 Estate Wagon, 2014 W212 Sport Wagon
Transmission let go at freeway speeds (P0700 and 720)
This is the second time this year that my TCM decided to lose its mind and let go of the transmission at freeway speeds. The first time it happened, I accidentally cleared the codes (this was 4-5 months ago). Today, it happened again and the codes were P0700 and 720.
Would cleaning the TCM connectors and harness be a possible solution to my gremlin (I know someone spilled beverage on my shifter area no more than two years ago)? Are these units flaky?
Just to share my experience, once the TCM let go of the transmission coupling to the engine, there was no way to re-engage it while cruising. You have to pull over, turn off the car and turn it back on again. I suppose I could have done that in neutral while coasting but probably not a good idea to lock your steering wheel OR engage the tranny at freeway speeds.
Would cleaning the TCM connectors and harness be a possible solution to my gremlin (I know someone spilled beverage on my shifter area no more than two years ago)? Are these units flaky?
Just to share my experience, once the TCM let go of the transmission coupling to the engine, there was no way to re-engage it while cruising. You have to pull over, turn off the car and turn it back on again. I suppose I could have done that in neutral while coasting but probably not a good idea to lock your steering wheel OR engage the tranny at freeway speeds.
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Joined: Mar 2006
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From: West Virginia
2001 E320 RWD - Brilliant Silver/Ash: 100,000+
That has never happened to me but I don't think cleaning the TCM will hurt anything and it might even help. I also think they are flaky by nature but once some liquid is spilled on them they can get that way quickly. Have you found a source explaining what the error codes are?
Thread Starter
Member
Joined: Jul 2006
Posts: 193
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From: Alameda, CA
1991 SC Miata, 1999 W210 Estate Wagon, 2014 W212 Sport Wagon
My code reader has the explanation for the errors (you can also google them). The first one pertains to a transmission fault and the second one pertains to speed sensing (relative to rpm I think).
I've read in previous posts that you can actually get codes from the TCM through the dealership. I might do that.
I've read in previous posts that you can actually get codes from the TCM through the dealership. I might do that.
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Joined: Feb 2008
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From: Charleston, SC
GL450
After a quick search, it sounds like that's an issue inside the transmission. However, cleaning the shift module probably won't hurt. There are some posts on here about it, but basically you disassemble everything and spray with some contact cleaner (some people use rubbing alcohol and a q-tip).
Can you describe what exactly happens when it "goes out"? In particular, if you floor the gas pedal (all the way down, so it depresses the switch on the floor) does it cause the problem? When it's out, is it truly out of gear, or is it in gear but very unresponsive (push gas, car waits 5 seconds, then very slowly accelerates)?
Can you describe what exactly happens when it "goes out"? In particular, if you floor the gas pedal (all the way down, so it depresses the switch on the floor) does it cause the problem? When it's out, is it truly out of gear, or is it in gear but very unresponsive (push gas, car waits 5 seconds, then very slowly accelerates)?
Thread Starter
Member
Joined: Jul 2006
Posts: 193
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From: Alameda, CA
1991 SC Miata, 1999 W210 Estate Wagon, 2014 W212 Sport Wagon
What appears to happen is a total disengagement of the transmission. It's like you're in neutral and when you rev the engine, there's no tranny that couples to it. Going to neutral and then shifting through the different gear settings does nothing either.
Once on the side of the road, I turn off the engine and restart. Then, Viola! I'm back on the road again with NO SIGN of transmission problem... shifting is smooth, rev is okay.
Once on the side of the road, I turn off the engine and restart. Then, Viola! I'm back on the road again with NO SIGN of transmission problem... shifting is smooth, rev is okay.
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Joined: Feb 2008
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From: Bostonian Ma
2012 CLS63 AMG
What appears to happen is a total disengagement of the transmission. It's like you're in neutral and when you rev the engine, there's no tranny that couples to it. Going to neutral and then shifting through the different gear settings does nothing either.
Once on the side of the road, I turn off the engine and restart. Then, Viola! I'm back on the road again with NO SIGN of transmission problem... shifting is smooth, rev is okay.
Once on the side of the road, I turn off the engine and restart. Then, Viola! I'm back on the road again with NO SIGN of transmission problem... shifting is smooth, rev is okay.
My .55 cents
Good Luck and keep us posted
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Newbie
Joined: Feb 2007
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1997 E320
This just happened to my 97 e320 yesterday. I was going about 75mph and when I floored it to speed up and it felt like the tranny attempted to downshift but never engaged. The SCARY part was that the engine REVed to +4500rpm and stayed reving 4500 even though my foot was not longer on the gas pedal... it did this for about 5-10 seconds and then shifted into gear on its own. It never happened again but now I am a little worried.
My car has been shifting very rough going from 1st to 2nd and 2nd to 3rd for the past 2 weeks.
Does anyone know if these are signs that the tranny is failing? do a lot of trannys fail on these W210s? I have 110k miles and was planning to so the tranny flush but now starting to second guess whats best for the car. Should I just leave the tranny fluid as is or replace it? Any chance the flush can introduce new problems?
My car has been shifting very rough going from 1st to 2nd and 2nd to 3rd for the past 2 weeks.
Does anyone know if these are signs that the tranny is failing? do a lot of trannys fail on these W210s? I have 110k miles and was planning to so the tranny flush but now starting to second guess whats best for the car. Should I just leave the tranny fluid as is or replace it? Any chance the flush can introduce new problems?
Senior Member
Joined: Oct 2006
Posts: 416
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From: Reno 911
2008 S63 AMG Designo Edition
Had a similar incident with mine a few months back and got a PO715 code. I was driving around 65mph basically in 1st or 2nd gear. Unknown to me, the tranny would not shift. I think the motor started hitting the rev limiter as I was losing power so I pulled over. I shut the car off, then started it and started pullling back onto the road and that's when I noticed my tranny was not shifting. It was stuck in a single gear and reverse would not engage. I limped it home taking side streets...took it in for service the next day. They had to replace the circuit board that is in the tranny. Been fince since.
I did have warnings this was coming though.....my tranny would slip into limp mode every once in a while. Not sure if this is the same symptoms as you as I got a different code.
I did have warnings this was coming though.....my tranny would slip into limp mode every once in a while. Not sure if this is the same symptoms as you as I got a different code.
