Petronio

Hi. I will really appreciate some help.

My ML 320 2000 transmission is on limp mode due to DTC P0743 Torque Converter Clutch Solenoid Circuit Electrical.

This is what I have done:

1- Connected OBD scanner, cleared codes and P0743 came back instantly and limp mode kept on.

2- Changed transmission oil, filter and TCC solenoid. Cleared the codes and code came back. Limp mode is still on.

3- Read somewhere that my scanner is to basic, and I need a professional one to clear de code.

4- Took it to the shop (not dealer) and their scanner cannot clear the code. It comes back. They checked continuity of the line from transmission computer to transmission conector, even the solenoid plate and it has a resistance reading, but the computer does not send a signal.

Is it the transmission computer shot or the limp mode does not transmit to this solenoid valve? Only the Star Diagnostic System can fix this limp?

Best regards.

Plutoe

Yep, that's why every Tom, Dick and Harry OBD scanner is just that a Tom Dick and Harry.

FYI; The TCU sends a fault message to the ECU enabling a cel------then the USA mandated ability to read ECU emissions related faults via the OBD alerts the driver to a transmission issue---however if you don't have DAS Xentry software you can't read the TCU and clear the fault---your foooooked---find someone that can read the TCU!!

Petronio

Can you recomend me a code reader with DAS Xentry software?

Plutoe

You need to read more, DAS Xentry is the code reader---google DAS Xentry and there are thousands of folks selling the software\laptop, the mux and cables. Just be patient a good set will cost you about USD800 and it will take you a month or two to learn how to use the software.

Petronio

Plutoe, right now I have a AUTEL OBDII Scanner Diagnostic Live Data Code Reader Autolink AL519, which has been very handy for my MB maintenance, but this is the first time I have transmission problems and this model does not erase codes on the TCM just the ECU. What do you think of upgrading to this Autel model:


Best regards.

Plutoe

I only work on MB's and therefore have no experience with non DAS Xentry software. However if Autel will read\offer diagnostic assistance(tests)\clear non emissions related faults resident in all MB control modules---why not!!

Petronio

Ok. Thank you very much Plutoe.

Best regards.

Petronio

Hi Plutoe,

The mechanic connected a LAUNCH X431 SCANNER, and he erased the solenoid code but it inmediately comes back. He says there is a CAN BUS problem between the engine and transmission computers. The harness cables have continuity, is it the transmission computer busted or you think it can be something else. Or the scanner is innadecuate.

Some tip will be greatly appreciated.

Best regards.

Plutoe

I don't know anything about the Launch X431, however yes there is a CAN bus issue because the TCU can't communicate with the solenoid and the wire connection between the TCU and solenoid is good---therefore sounds like you have a bad solenoid!!

Maj. Dundee

That model will read and erase the 3 digit codes in the ETC.

Petronio

Ok. Thanks Plutoe.

Petronio

Ok. Thanks Maj. Dundee.

Petronio

All codes were erased. The transmission worked fine for a couple of days and now is in limp mode again. Codes are P0753 SHIFT SOLENOID A ELECTRICAL and P0715 INPUT / TURBINE SPEED SENSOR A CIRCUIT.

Are the shift solenoid 1-2 and the speed sensor faulty or the solenoid conductor plate faulty?

Plutoe

Solenoids are replacable the speed sensor is apart of the conductor plate and to replace a speed sensor you re[lace the conductor plate!!

Maj. Dundee

Please UPDATE YOUR PROFILE in USER CP.

Maj. Dundee

How did you change the TCC solenoid?

On the right side of the transmission you will find a 13 pin connector. Separate it and in all probability you will find trans. fluid between the two halves. If so, the connector must be replaced with an original equipment part purchased at a dealer.

Code P0743 is a transmission code which is reported by the ECM, and as a result a 3 digit code is stored in the ETC (Trans. Control Module). That code will be either 005 or 101.

After replacing the 13 pin connector and the little fluid that you lost doing so, you must clear the P0743 from the ECM and then you must clear any and all codes from the ETC.

If you do not clear the codes from each module separately you will continue to be in Limp Mode.

Do you understand everything?

Petronio

Thanks for the info, everyone. I changed the conductor plate, erased the ETC codes and everything went back to normal.