2020 750i m package rebuild. need help with EPS

[OhThatsG]

to all my fellow 7 guys, im mechanically inclined with some help obviously on this level of a car. but i bought this hit in the front pretty much engine forward needed to be replaced, wires to the rack and the connector on the eps motor was damaged, so i installed a used low milage tested electric power steering rack in it. mind you i had eps codes prior due to the wires etc. No airbags deployed, seat belts in tact i have cleared every code and all im getting back is zero communication to the EPS. i ran brand new oem electical lines for the rack. im just confused because i cannot find a fuse relay module etc anywhere. but there is so little info out there and its been quite hard rebuilding this car. but im almost done i just need some of my tech savvy guys to share there knowledge! PFA!!!!

[Raimo5]

Hi,

Most important thing is to make sure that it is indeed correct steering rack. If the car has Integral Active Steering, then with this engine variant, there should be 24v steering rack. If it comes without IAS then your rack should be 12v. These are non-interchangeable and correct rack must be installed or it wont work.

It is also required to initiate the startup procedure via service module. I will attach some documents that will hopefully assist you in troubleshooting.

[OhThatsG]

i confirmed with the dealer with the VIN it did not have active steering. nad the plug itself was indeed only 12V and thank you for posting those attachments!🔥👊🏻

[OhThatsG]

hey raimo! i also had another question, you seem to know whats going on with the newer bmw’s im having a issue where the car will not go into any gear. if i shift to drive it’ll go back into park after a few seconds. same for neutral and reverse. if i manually put it into neutral underneath the car it will show neutral on the shifter. would you happen to know what i should do? my friend is a tech/teacher for the new EV cars. he knows alot about electrical we didnt spend much time last night trying to figure it out as it was late but id like to help him with some info if you could

also, i tried all of the above. but having no power to the positive wire that runs from the power supply to the eps. maybe a blown fuse?

[Raimo5]

Hi!

Always glad to help out if I can.

There can be quite a few reasons for gear inhibiting, but only one I have seen in practice is insufficient brake pressure. Does the brake pedal feel good and solid? If not, then proper brake bleeding routine with diagnostic system has to be carried out so that fluid pressure sensor would unlock the gearbox. It is a common thing for post accident repairs that have involved brake system. It could also be other things as I have mentioned, but in that case, a trouble code should be read out and go from there.

Regarding power steering - is it possible to have a blown fuse? Of course, especially considering that the car previously already had EPS faults entered. You should check Power Distribution Box 'Z4' in engine compartment as per wiring diagram as it provides the power to connector A67*2B via fuse F401. It could be that fuse is blown in there or there is an issue upstream from it.

I will attach few more documents to help you with diagnosing power distribution box.

[OhThatsG]

i figured it was going to be a issue with the distribution box, but i wasnt quite sure but after talking to the dealer looking into it myself more and just reading your text… i did order a new one. are there are built in fuses into the distribution box as well guessing thats what not allowing the eps to have power.? it looks like a sealed unit. i did order a new one of course none in the states and its coming from germany. and as far as gearbox not shifting i was low on transmission fluid 🤦🏻‍♂️

i think i should be able to sort it out from here, i very very much appreciate your time and knowledge for helping me and taking time out of your day to do so. are you a tech here in the states?

[Raimo5]

I'm not entirely sure as I haven't opened any of those power distribution boxes, but it doesn't state that these are non-serviceable anywhere in the documents, unlike rear fuse box Z3. From the looks of it, there should be 150A fuses in there that are p/n 61139283441.

I mentioned that there could be a problem upstream from this box, and that comes increasingly more important when dealing with collision scenarios. I should have mentioned that before and I'm sorry I didn't. Front power distribution box is connected to B+, but it is not connected directly to battery, but to rear fuse box Z3. This fuse box connects B+ power to Z4, but it is internally switched by a relay that is controlled by Advanced Crash Safety Module (ACSM). Now, the collision wasn't too severe as you mentioned, but anything can happen and that is why it is necessary to physically trace the discontinuity to its source.

If you have power on connection Z4*1B, then all is good there, but if not, then fuse box Z3 might be your actual issue. Either way, fuses in Z4 can be checked and I think also serviced. If you are going to do that, then identification of proper fuse in there is critical, as it has fuses on both sides of the power plane.

I will attach wiring diagram and schematic for fuse f401.

Glad you got gear inhibitor sorted out. Mind I ask how you came to this conclusion? Were there trouble codes set for low fluid level/pressure and how did it end up with low fluid level in the first place?

I'm from Estonia, so across the pond. I'm not a technician, but I do love to wrench on cars and troubleshoot them. I have a passion and love to share it by helping others, so others could enjoy their vehicles to the fullest as well. And should I see a chance to learn something new then all the more reward from it.

[OhThatsG]

so with the help of my friend and his nice scan tool, we tried diag but there really wasnt any errors. i could manually put it in neutral from underneathet (lever thats next to the driveshaft on the transmission) and from the hit the transmission cooler was broken badly so i replaced it but i guess a good amount of transmission fluid came out. (we added 3 quarts and it still needs more…) but that had to be the only solution after not finiding and data and troubleshooting. also thank you for the schematics on how to service it! it looks like a sealed unit from the outside thats why i was confused. also i will indeed dive into check z3 to make sure all is good there! and right on your technical troubleshooting levels are that of technicians. all i can say is bravo!