trans. locks up sometimes, and just recently into limp mode.
Thread Starter
Joined: Dec 2008
Posts: 2
trans. locks up sometimes, and just recently into limp mode.
I have a 01 C320 that is acting up.The first thingit started doing is that the trans. would lock up like it was in neuteral at times. I would pull over, shut the car off and restart and the way I would go.Now, the car hasn't been driven for a couple months and when I tried it would barely move. It acts like it's in limp home mode.I ran OBII code reader and it gave me PO700, & PO120.Please, can anybody help me on this, I need it back on the road.
Senior Member
Joined: Dec 2004
Posts: 2,410
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RE: trans. locks up sometimes, and just recently into limp mode.
P0120 is a throttle position sensor circuit issue.
P0700 is a transmission Trans Control System issue (MIL request)
Where MIL = Malfunction Indicator Light.
Not actually experienced this one before but it looks as though the trans ECU isn't seeing the throttle input in which case it doesn't know what to do.
Since I assume the engine responds to throttle (when stationary) I guess it could be one of the trans connections gone open circuit.
However maybe the engine isn't seeing the signal either?
Ignition off resets the systems but maybe the throttle sensor is OK with foot off but goes open circuit as it is pressed.
I would most probably start with taking a look at the transmission electrical connector. Remove and refit noting any fluid leakage / corrosion on pins etc.
If there is leakage take the opportunity to correct this by fitting a new trans (electrical) adaptor. Common MB problem.
However a bit of oil shouldn't upset the connection but it can track up the harness and cause other problems.
Any other bits of info that may help. Mileage, other symptoms etc.
Could be the trans ECU / selector but I don't have any experience to warrant changing this (expensive) on the evidence available.
What's causes me a problem is that the engine ECU isn't reporting a similar fault.
Stuart
P0700 is a transmission Trans Control System issue (MIL request)
Where MIL = Malfunction Indicator Light.
Not actually experienced this one before but it looks as though the trans ECU isn't seeing the throttle input in which case it doesn't know what to do.
Since I assume the engine responds to throttle (when stationary) I guess it could be one of the trans connections gone open circuit.
However maybe the engine isn't seeing the signal either?
Ignition off resets the systems but maybe the throttle sensor is OK with foot off but goes open circuit as it is pressed.
I would most probably start with taking a look at the transmission electrical connector. Remove and refit noting any fluid leakage / corrosion on pins etc.
If there is leakage take the opportunity to correct this by fitting a new trans (electrical) adaptor. Common MB problem.
However a bit of oil shouldn't upset the connection but it can track up the harness and cause other problems.
Any other bits of info that may help. Mileage, other symptoms etc.
Could be the trans ECU / selector but I don't have any experience to warrant changing this (expensive) on the evidence available.
What's causes me a problem is that the engine ECU isn't reporting a similar fault.
Stuart
Thread Starter
Joined: Dec 2008
Posts: 2
RE: trans. locks up sometimes, and just recently into limp mode.
Thanks for the reply.Hopefully it's something I can fix myself, with help from people like you of course. Only other problem I may have is trying to locate these areas. Do you or any body else you can think of have any pictures or web sites that would have any pictures to give me an idea of locating these parts. that would be great cause I'm lost under the hood and don't have a clue of where to look and what I'm looking for. Again, thanks for your reply, you just never know what will work untell you try.
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