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Lou P.
Lou P., ASE Certified Technician
Category: Transmissions
Satisfied Customers: 4814
Experience:  I Have knowledge in almost all car lines and can help with general questions and more!!!!!
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My mercedes is a c230 1997 with trasmission 722.6 and is in

Customer Question

My mercedes is a c230 1997 with trasmission 722.6 and is in limp mode, works only in second gear, the scanner gave me the codes P0715, p0720 and p0730 I have no voltage for the solenoid, voltage for sensor and ECU fine.
JA: Which particular sensor are you asking about? And have any trouble codes been triggered?
Customer: I have problem with the speed sensor.
JA: Are you fixing your C230 yourself? What have you tried so far?
Customer: I replaced the engine
JA: Anything else you want the mechanic to know before I connect you?
Customer: I just want to get the car out of the limp mode.
Submitted: 8 months ago.
Category: Transmissions
Expert:  Lou P. replied 8 months ago.

Hello, my name is***** and i will do my best to assist you.I am going over your story now and will reply back soon with some info,thanks!

Expert:  Lou P. replied 8 months ago.

What kind of scanner are you using ? Brand and model ?

Customer: replied 8 months ago.
I am using the LAUNCH scanner OBDII VIII.
Customer: replied 8 months ago.
Launch Creader VIII
Expert:  Lou P. replied 8 months ago.

Ok , do the codes come right back when you erase them out of the transmission control module (etc) ??

Customer: replied 8 months ago.
the codes came back after erasing them out of the transmission control module (etc).
Expert:  Lou P. replied 8 months ago.

ok sorry for the delay, looking over the meaning of the codes now to see what we can do, i also have a launch scanner and i love it it does a lot of what we need for the mercedes.

Expert:  Lou P. replied 8 months ago.

ok, have you tested for power to the solenoids at the trans connector of the trans?

Expert:  Lou P. replied 8 months ago.

the problem with the p0715 code is that it can have a few different meanings, did all of this happen after replacing the engine?

Customer: replied 8 months ago.
I guest the missing power to the solenoids is part of the limp mode. Yes the transmission was working fine before I replaced the engine.
Expert:  Lou P. replied 8 months ago.

ok, did you disconnect the trans module at all because one connector on the trans is for the trans itself and the other connection is for the body harness for power and ground and communication.

Customer: replied 8 months ago.
I did not disconnect the module.
Expert:  Lou P. replied 8 months ago.

ok, unplug the connection on the trans ,check for positive voltage on the white wire, it will be pin 6 on the trans connection, i will send over a picture of how the connection looks.

Expert:  Lou P. replied 8 months ago.

here is the connection

Customer: replied 8 months ago.
OK I will do that tomorrow, the electrical plate in the control valve I replaced, new one. Regards.
Expert:  Lou P. replied 8 months ago.

ok, did you replace it because of this issue? or did this happen after replacement?

Expert:  Lou P. replied 8 months ago.

let me know tomorrow what you find, i can help you get this going, have a good night,Please take a second and click the STARS above and rate my service 4 or 5 stars if you feel I have been helpful and please request me in the future. Keep in mind that when you rate it does not end our conversation, you can still return here to me for follow up information if needed, Thanks for choosing just answer. Also , if you feel i deserve one , BONUSES are GREATLY APPRECIATED! Thanks again , Lou P.

Customer: replied 8 months ago.
Hello Lou I just disconnect the connection to the transmission and no voltage for the solenoids. I replace the electrical plate because oil was leaking , this is common problem with this car.
Expert:  Lou P. replied 8 months ago.

ok yes common problem is the oil leak, but the fix is to replace the small plastic conenctor that goes between the trans and the electrical connection, ok so now we need to access the trans module and make sure the white wire is good from the connection to the module.

Expert:  Lou P. replied 8 months ago.

the transmission module is located under the passenger side front carpet, near where the feet are at. here is a picture

Customer: replied 8 months ago.
The white wire has continuity, when I turn the ignition no voltage, the TCM pin #29 shows voltage, pin 38 is the voltage for the solenoids is not there. Is this an internal problem with the TCM or because the central computer does not allows to switch the voltage because of the codes relate to the speed sensor.
Expert:  Lou P. replied 8 months ago.

you will always get voltage whether codes or no codes. it will just not pulse the ground for the solenoids.

the other power wire 29 like you have found. if you can communicate with the tcm then we know we have good power and ground,

it sound like the tcm has failed, to recheck erase the codes and have the wires plugged in and back probe the white wire and use the scan tool to activate the solenoids, that should tell you if the module is sending out power.