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Ask Chad Farhat Your Own Question
Chad Farhat
Chad Farhat, ASE Certified Technician A6 - Electrical / Electronic systems A7 Heating / Air conditioning systems
Category: BMW
Satisfied Customers: 3449
Experience:  Owner at Carolina Auto Service & Sales , 20 years Experience in Foreign & Domestic vehicles
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I have a BMW 735i 2002 i get those error code Communication

Customer Question

Hi, I have a BMW 735i 2002 i get those error code Communication with switch group steering column faulty transmission position sensor fr st col electr no plausible and gearbox faulty
JA: Which particular sensor are you asking about? And have any trouble codes been triggered?
Customer: the mecanic sayed is a electric problem he delete de code a couple of time but they appear again
JA: Are you fixing your 735i yourself? What have you tried so far?
Customer: i change to a new battery, i bought a new lever gearbox and replace it i've changed the gearbox oil
JA: Anything else you want the mechanic to know before I connect you?
Customer: i think is enough
Submitted: 10 months ago.
Category: BMW
Expert:  Chad Farhat replied 10 months ago.

Hi, I'm Chad. Welcome to JustAnswer. I'm reviewing your question and I will be posting your reply ASAP.

Expert:  Chad Farhat replied 10 months ago.

I will need the fault code number received by the shop to tell you excatly what is going on and what you need to test ?

what is the car doing now ?

what is the mileage ?

Please let me know

Thank You

Chad Farhat

ASE Certified Technician

Customer: replied 10 months ago.
Error codes:5079 Serial data bus CAN Timeout
5147 Communication with switch group steering column Faulty
50DC Transmission position sensor Msg fr st col electr not plausibleOn board display:Gearbox faulty(most of the times)
DSC sensor (faulty sometimes)
Gearbox impared(sometimes and I can drive the car)
Airbag, seatbelt no active....
Customer: replied 10 months ago.
what i've done so far:1.reset the error code(a couple of times)
2.change the gearbox oil
3.change the lever shifter gearbox
Customer: replied 10 months ago.
137.000 milesis showing the error message gearbox faulty can't put it in DRIVE, PARK, or REVERSE
Expert:  Chad Farhat replied 10 months ago.

1-have you checked battery for 12 volts

2- battery cables for corrosion or loose

3- alternator charging 14 volts with all loads on ?

what is the mileage on it?

Customer: replied 10 months ago.
1.battery was changed to a brand new one.
2. i will check
3.i will check137.000 miles
Customer: replied 10 months ago.
sometimes is working, but after i stop and leave the car for 20-30 min. will not work.
Customer: replied 10 months ago.
but very very rare when is working, i couldn't use the car for 4 months now
Expert:  Chad Farhat replied 10 months ago.

we have to start here, the cable corrosion is number one issue for the fail safe trans issue, the other stuff needs checking .

make sure you have ac on, headlights on, flasher radio when testing for 14 volt sat battery when running

and when you do let me know

this post will stay open between us , if you not with car now

Customer: replied 10 months ago.
sure, so i need to check the cable in the boot that is connected to the battery?
Expert:  Chad Farhat replied 10 months ago.

yes that is correct

check & let me know please


Customer: replied 10 months ago.
Hi,I've checked the cables today they look ok..I've attached here some pictures.Thanks,
Expert:  Chad Farhat replied 10 months ago.

hey lucas , yes everyting looks good

Expert:  Chad Farhat replied 10 months ago.

how is our voltage ?

Customer: replied 10 months ago.
the voltage is varying but is around 14 volts
Expert:  Chad Farhat replied 10 months ago.

if you rev it up still around 14 .

trans module checked , unplug the connector & check for backed out pins making poor contact .

Customer: replied 10 months ago.
Where is the trans module and how I can unplug and connect?
Customer: replied 10 months ago.
If you have a picture where I can find it will be perfect
Expert:  Chad Farhat replied 10 months ago.

the control unit is internal

but you can check connector ,I make sure no oil in the connector leaking from inside to it ,i sent you pictures .

EGS Control Unit: The EGS on the 6-HP gearbox is fitted as part of the gearbox and no longer as a separate control unit in the Electronics Box. It evaluates the sensors electronically and directly activates the hydraulic unit. A temperature sensor of the EGS processor additionally monitors the gearbox temperature

just double check you have that connector , i want make sure it doesn't change in the u.s. here than u.k

Let me know if you need anything else on it ,just reply back & we can continue

if you are good , Please Kindly rate me.

Hope I was helpful to you

A Positive Rating is Much Appreciated

This Post Will Stay Open for You To Come back and Ask me Any Follow Up Question You May have on this issue , even after you rate me

Thank You Lucas

Chad Farhat
ASE Certified Tedchnician