DIY: S65 Throttle Actuator

[drummer20]

Originally Posted by M3amigos

Two shops confirmed that my alternator is bad. Autozone had an OEM reman for only $170. I installed it and voltages are back to normal levels. I drove around for about 3 hours without any codes, so thats promising. we'll see how it holds up this week, but i'm happy to have escaped complete TA failure with just the gear rebuild and alternator replacement.

Side note, was excited to find out about the hidden service menu on the dash display. I was able to turn on the voltage monitor which really helped troubleshooting. For anyone that hasn't seen it, check out this site...
http://e90.wikifoundry-mobile.com/m/...C+hidden+menus

Glad to hear you figured it out without having to shell out for new TAs

That's interesting I didn't know about the hidden service menu. Might come in handy one day

[Koo]

One of my actuators went bad about a month ago. I installed odometer gear set on both sides and that didn't fix the issue. The code that was thrown at me was P2100 which means something is wrong with the bank 1 actuator.

I replaced the 5 mosfets today and the P2100 was still thrown at me. I'm not sure if resetting the code would help but I don't think I can do it with my bluetooth OBD2 scanner.

I'm about to buy a new TA but at least I only have to replace 1 of them :S

[Koo]

I just placed an order from fcpeuro. With 2 day shipping I paid "only" $880 and they have LIFETIME warranty on it. With this part, they probably shouldn't have one :P

https://www.fcpeuro.com/products/bmw...m3-13627838085

[M3amigos]

Clearing the code would be recommended. While the manifold was off, I was able to turn on the ignition and have someone press the gas pedal in and out to verify operation. If there were still issues it would likely be noticable comparing between the two banks. Theres also a good chance something else was burned out on the circuit board. I swapped the board from one to the other to check and my code never followed. I thought I had a bad motor until i realized that my battery/alternator voltage was very low~11V. After a recharge everythinng started working as normal.

Best of luck, hope you get it back running soon, I know the feeling to have to deal with this expensive issue.

[X5-User]

I just got P1628 code for the first time !

I read though all this thread and cant get a straight answer if replacing the gears would solve the problem at this stage. Can someone confirm?

[drrust]

You are right it is not clear if new gears will solve the problem or not. The only way to know if the electronics have been damaged or not is to replace the gears and try it. Some suggest you can look at the MOSFETs and see the ones that were damaged. Either way one has to remove the actuators, which is the most time consuming part.

One question is: Do you have other transportation options or not? If you positively have to fix it in one shot and don't want to have to do it again, replace both actuators with new ones. It is interesting that someone is guaranteeing them now (need to know the fine print).

You can lower your cost by replacing the gears on the unit that is not throwing a code. But as one has to buy the gears in sets of two, it raises the question of whether or not to try to replace the set in the one throwing the code. Which brings one back to the original question. If you order a new actuator, there may be a restocking fee if you try to return it.

As I DD my car and it had over 100,000 miles on it, I changed the gears before a code was thrown. The amount of wear on both units was similar to what is shown in previous posts in this thread. So I think that if one has thrown a code, the other is close to failing.

Whatever route you take, DIYing it definitely is the more economical than taking it to a shop.

[Koo]

Bad news for me. I just installed a brand new actuator on bank 1 and it's not moving at all. Bank 2 worKS great but seems like bank 1 has a problem that's not related to the actuator. Someone mentioned about an alternator, could this be the problem?

Again, bank 1 opens and closes but bank 2 doesn't even with a new actuator.

Edit: Silly me forgot to add the arm to the actuator and now everything works great!

[drummer20]

Originally Posted by Koo

Bad news for me. I just installed a brand new actuator on bank 1 and it's not moving at all. Bank 2 worKS great but seems like bank 1 has a problem that's not related to the actuator. Someone mentioned about an alternator, could this be the problem?

Again, bank 1 opens and closes but bank 2 doesn't even with a new actuator.

It seems like your post contradicts itself about which banking is working....
An alternator would affect both banks equally I would think so I doubt that is the issue.

Double check that all the connectors are plugged in good! Also I would verify the new actuator is actually good by putting it on the bank that's working now...it could be a dead on arrival

[Koo]

Yeah sorry I confused the banks. Bank 1 wasn't working while bank 2 was. It now works and I was finally able to drive my car after 1.5 months of waiting. No error codes or lights

[drummer20]

yea I definitely understand about the 1.5 month wait, that's about how long my M was out of commission when I rebuilt my TAs :-/ I broke a gear and shaft and had to borrow two different presses. My press fit washers were crazy tight for some reason.

So what did you do to fix the non working bank?

[M3amigos]

So it's been about a month since my TA gear and alternator replacement and all was well until this past weekend when limp mode and the codes for bank two came back, same as before. I happened to be working on my convertible top, opening and closing it a bunch of times with the car off, so I suspect the battery was a little low on charge. After letting the car run for a few minutes, I restarted and limp mode went away. I had hoped it was just a random occurence but twice again today it went into limp mode upon a cold startup and then cleared itself upon a restart.

My bank 2 actuator has a strange symptom in which it seems to act up more often when the battery voltage is low, much like when I had the bad alternator. I wonder if that is related to excessive current draw from the failing actuator which is possibly masked when battery voltage is at its peak.

During previous troubleshooting, I found that switching the circuit boards from one to the other did not cause the failure to switch to the other side. This leads me to believe there is either an issue with the wiring or an issue with the TA motor. The wiring seems less likely, so I think my next step to troubleshoot will be to swap the whole actuator from side to side and see if it follows in that case. I may also remove the motor and blow out the inside with compressed air and see if that helps any.

Anyone have any other suggestions. I'm still hoping to get lucky with a DIY repair rather than having to shell out the $900 for a new TA.

[M3amigos]

Also I recall reading that the first step the dealer would try would be to do some sort of software update. Is there a specific module that gets coded or just an update to the latest DME version? Can the TAs be reprogrammed with updated firmware? I believe I got the 240e dme update a few years ago with my BPM tune but I wonder if there is something additional that could be done for the TAs.

[drummer20]

This does sound like the motor is on the decline. I would definitely try switching it to the other side. Cleaning it is worth a shot....I read on some M5 board thread that the motor sometimes needs a lot of persuasion to be removed and the guy who did remove it, actually damaged it. So be careful, I think it's glued in the back to the housing. Maybe heating the housing or something thermal would help

[Medi1985]

So I have done the gears and the mofset's on both actuators and the initially faulty actuator still throwing codes...When starting the car it's hit or miss. 1/6 times of starting the car it seems to be without fault but the other times it's comes on from start of after 5 mins of idling/driving. From a visual inspection of the rest of the board I have notice a difference between the bank 1 and bank 2. I have noticed little blemish in what I think might be some kind of resistor. I don't know if anyone could possible source this of if its even possible to swap but just courious before I but a new actuator. Thanks in advance for any incite.

[drummer20]

It is a MELF resistor and yes you can buy them on Digikey or Mouser.com. The color bands are coded so you can tell what value and tolerance they are just by looking at them which is nice. They should be easy to swap out with a couple soldering irons. Also you could try puttting a ohmmeter on them and see if it matches the color code value. You might be able to verify the value without removing it, depending on the circuit. However if the value doesn't match with it on the board, you should remove it from the circuit board and check it separately. It doesn't really look damaged but you never know without measuring. It does appear the ends where the solder goes looks different from the others.

[Rostasteve]

Has anyone tried or heard of http://www.rebuild.org.uk?

It's a "shop" in the UK that will rebuild both actuators with new gears and MOSFETs for £379 with US shipping. And can test them on an M6 rig before shipping back.

[M3amigos]

Update on my ongoing struggle and some recent progress. After swapping the gears and running ok for a month, I Started getting codes and limp mode again on the same bank as before. Again the error started gradually then developed into every start up.

So I removed the failing actuator (getting good at it now, took less than an hour) and opened it up. the gears looked fine, and the circuit card looked ok. Now last time I installed them, i thought I had swapped the cca from side to side but I was wrong, I had swapped the motor housings instead according to my markings. So to retest the cca, I went ahead and swapped them properly this time, started up the car, and sure enough the code switched to the other bank.

So knowing that the cca was now the cause of the failure (and not the motor after all) i swapped out the 5 mosfets on the board. For a novice at soldering like myself, this task was not as easy as it looks/sounds. You need a decent soldering iron to heat up the very large solder pad under the chip. I have a cheap adjustable soldering station and i had to crank it all the way up and heat it for several minutes before it would budge. It took me a while to get the first few off before i got the hang of it. The trick for me was to score the outer conformal coating of the board with tweezers, then desolder the two small legs (which in most cases broke off from the chip), then heat the large leg while pulling up with tweezers. I cleaned up the pads the best I could and soldered the new ones in similar fashion, short legs first, then heat the large leg/pad applying pressure to the chip with tweezers til it sunk down. It wasn't pretty, but i luckily removed and replaced all 5 mosfets without ripping a pad or other components off the board, although i did accidently melt both connectors for the motor. i figure i didnt have much to lose at that point anyway.

So in the end, I got the circuit card reinstalled and it started right up fortunately. i had to clear the codes before the limp mode went away, but i started it a dozen times and all was well. I got the car put back together in record time, and its been running fine for the last two days. fingers crossed again to see of it holds up, but i have a bad feeling that i'm just buying more time before it craps out again.

Its sad, but i've really been thinking hard about having to deal with this and other problems in the future now that i'm pushing 100k miles. I'm debating whether to trade the car while its still running, but really can't find a comparable replacement under $40k so i'm holding on for now.

[M3amigos]

Here's a before and after pic of my mosfet replacement:

[drummer20]

Yea it's not easy with just a single iron, in fact any board work is not so great with a single iron.
This one has a hot air blower that will take you far.
https://www.amazon.com/gp/aw/d/B01AM...=ABWUOVROUU2BE

Or a luxurious one with a preheater and a blower holder.. https://www.amazon.com/gp/aw/d/B019L...40_FMwebp_QL65 I actually have the second one...it makes it pretty easy but it's an investment in your time and stress level

Although even just two irons works pretty well

[M3amigos]

That's pretty cool, I may have to look into upgrading one day. Back in my cell phone repair days, we used a tool called a flowmaster which was basically a big heat gun mounted on a stand. It heated a whole section of the board and you could easily pick and replace multiple components. As I venture into more complex DIYs, it makes for a good excuse to invest in more and more tools!

[tonyfoto]

Replaced both actuators yesterday. Took about 2 and a half hours! Wasn't hard at all and saved about $1200 vs. Dealer's quote.

Thanks for the great DIY

[Crypty]

Originally Posted by Crypty

I replaced my bad actuator and now things are just great. Idle seems smoother. All error codes have gone away. One of the most annoying things about this problem is the amount, and variety of codes thrown. They seemed to change slightly after each clear. I had one point me at my throttle position sensor, which of course was not the problem.

I'm going to open the bad one back up and see if I can visually spot any flaws on the PCB.

I'll just quote myself here because today marks EXACTLY 1 year since I replaced my bank 1 actuator with a new, genuine BMW actuator from ECS and it once again seems faulty with code 2B25.
I called ECS expecting to have a terrible convo but they informed me BMW parts come with a 2 year warranty so I have another one on the way and will send the dud back for a refund. THANK GOD.


This does get me thinking that there is probably something else at play with this engine than the actuators themselves. I like the theory on lubricating the linkages. I noticed mine were slightly squeaky, so I lubed them all today in an attempt to "save" my actuator and stop codes being thrown. That didn't help, but now they are quieter and hopefully moving more freely. I think if these linkages are not moving easily it makes sense that this could stress the motor and would cause pre-mature failure. It might explain why my bank 1 actuator blew, and then blew again. Maybe I had a stickier bank 1 than bank 2.