Transmission problems, help needed
 

Hi everyone,
I am new member but I was reading a lot on this site before I registered and I see there is a lot of knowledge here.
I bought 2003 X5 4.4i with transmission problem, I am mechanic and I have no problem fixing many things including engine but I am not very familiar with automatic transmission.
I will try to explain what is going on as short as possible.
Car starts good cold or hot, but transmission works fine when cold, after 10min of drive it suddenly revs rpms and goes to fail safe program with hard bang to 5th or sometimes to 4th gear. I have scanned it and there is several things showing up.
Transmission temp is -55c
Replaced harness in transmission and still same reading.
Solenoid 3
Map cooling activation
5A brief power interruption
Dynamic stability control
And also weird wheel speed reading when parked it is showing
LF 0, RF0,
LR 4850 rpm
And no RR wheel at all.
Is there anyone who had this kind of problem and is there solution to this.
I just want to make sure that problem is transmission it self not something else causing it to fail.
Excuse my English, it's not my first language.
Thank you in advance

Crazy abs readings and DSC errors often from internal design flaw in the abs module.

Make sure your connector is clean to the transmission but I think you said you changed the harness so that's not likely the problem.


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Thanks for reply
Yes I have replaced harness and plug looks like new and harness in general,
Didn't find any particles in oil pan, I am just totally confused with temperature reading and fact that it drives totally fine when cold, it shifts nice and manual shift works as well.

May try swapping the left and right rear wheel sensors and seeing if the error follows the sensor. RR 4850 LR0. It’s possible it’s shutting itself down because of the drastic difference in the speed sensors.

I know you can clean and recalibrate those as well but you’d need a laptop with the bmw tools apps on it...

That makes perfect sense, I will do that first. I have to try all options before I remove transmission.
Can it be something wrong with TCM as it's reading ATF temp as -55 always, and even engine temp after 1 min. idling shows 124c.

The transmission suoerman said the harness sensor can read off and not the biggest concern but your is seemingly reading min temp so either open or short so I would track down which. If one wire shorted likely others.

You said you replaced the harness. So you mean inside or outside ? The temp sensor is part of the inside harness iirc.


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I replaced inside harness, hoping to get different results and move from death point but nothing changed.

Trace the wheel speed sensor wires from the wheels through to the harness all the way to the connectors. Others have had problems with cracked insulation and grounding out and getting odd issues with ABS and transmission. Mine only happens when it rains and I'm trying to track it down currently.

It looks like some wiring issues, I cant believe to have so many different codes and all wrong readings.
Thanks for advice

Transmission error when rain or wheel sensor?


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Mine is that the ABS locks up and doesn't release when it's wet and the trifecta lights go on. If you go forward and backwards it will release.

Since this is a new to you car. Stat looking at the stuff that jumps out at you. The wheel speed sensors are a huge problem. You need to monitor them live and see what’s going on. I would even check the hubs. A wrongly installed wheel bearing will cause wheel speed sensor issues.

I bought car with transmission problem but seller is older guy and didn't know much about it, I did monitor wheel speeds live and left rear is showing 216rpm while front ones are 16( I was going slowly) and right rear wasn't on board at all. What is confusing is that it all works fine when cold. Do you think that it can be sensors issue even if it happens only when warms up.

More likely internal abs module if you get intermittent wheel sensor speed issues. There is a design flaw how the connector is wired to the motherboard. You can swap a couple speed sensors to test if it's the sensor (move and the problem migrates).

That said the sensors are very sensitive and rust on the sensor or bearing will throw them off.

Thank you, I will try that first.

I've followed at least 5-6 threads with similar symptoms and it ended up being the abs module. All the sensors and more are wired through the module. There is a well known issue with the wire bonding on them. There is a guy that will rework the bond wires for about $200.

If the hot/cold is repeatable you could pack some insulation around the module to see if the problem is delayed and confirm it's in the module.


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I have noticed that hot/cold is repeating all the time, I will do that first before I start digging further.