Can anybody work out a replacement transistor? BMW E36 ECU

[ardy89]

Hi all,

Having spent a few hours last week tracing the cause of a misfire I have discovered a transistor has blown inside the ECU, caused by a faulty ignition coil (since been replaced):

https://ibb.co/TqCnPR9

Now it seems rather difficult to get a hold of one of these, with exception of getting it from America. I could also buy another ECU and transfer into mine, something I am looking into.

Does anyone here understand the specification of transistors and can recommend the equivalent part from a different manufacturer. From my research, the transistor I am replacing is a Motorola STP8055.

Any help would be appreciated.

Cheers

Rob

[harrycovert]

I have used this site when looking for electronic components.
https://alltransistors.com/mosfet/

[ardy89]

Thanks for that, its just difficult not knowing the specs of the original.

[BFleming]

I suggest you contact Endtuning.com. Birmingham based, but knows his way around BMW ECUs having done some work for me in the past. Contact him, describe your problem as best you can (or cut & paste the first post fro this thread as it's comprehensive), and he will soon advise if he can help. I'd be surprised if he can't.

[Zico1]

I cant find the data sheet for Motorola STP8055 on the internet.

I think Motorola semiconductors became Freescale semiconductors.

I assume 80 = 80 mOhms (RDSon)
55 = 55 Volts breakdown voltage (VDS)

not sure what the threshold voltage would be without see the datasheet

An image of it looks straight leaded so probably SOT78

So look for the Freescales version

then try Nexperia, Infinion or ST semiconductors as they will all make similar devices.

[s38b36]

Here's what my googling came up with:

[s38b36]

.. for the MS41.0 ecu that is.

[ardy89]

Thanks for that, without the specs of the original how did you determine that was correct? Not saying you're wrong but before I go purchasing anything I want to ensure this right.

Cheers

Rob

[s38b36]

Here's a link to what I found.

http://www.romraider.com/forum/viewtopic.php?f=42&...

[ardy89]

Thanks for that, I'll look into it and report back.

[Zico1]

Unfortunately it is not a 400v IGBT you need.

It is a 55V, 80mOhm power mosfet you require.

The numbers on the failed device are the give away.

The awkward lead form suggests it may not be something you can just buy off the shelf.

Even if you do manage to locate a replacement, it may fail again unless you understand the original reason for failing.

I would personally probably source a replacement module from a scrappy rather search for the Tx.

[ian332isport]

I’ll have to see if I can find it, but I’ve got an old e36 m3 mss50 ecu floating around somewhere. It’s already donated one ignition driver in the past, and I’m pretty sure it’s the same part.

Ian.

[ian332isport]

That took less hunting than I expected.



I can remove another one if it helps.

Ian.

[ardy89]

Thanks for the offer, I ended up buying a second hand ECU and taking a transistor out of that. Now I have plenty of spares.

Transplanting that to my ECU has done the trick!

Cheers

Rob

[ian332isport]

No probs. Glad you got it sorted.

Ian.

[Spity6]

ian332isport said:

That took less hunting than I expected.



I can remove another one if it helps.

Ian.

Excuse me for butting in but l could sure use one of those transistors, l have a sick e36 in need of a STP8055 or equivalent. ( pretty please ) 😃

I

[ian332isport]

Send me your details and I’ll get one in the post.

[Eamonn-7p1oh]

I have just opened a friends ECU to find a blown component (not the transistors in the photo) It's on the other side perpendicular to the 6 transistors.
Would anyone have a schematic for this ECU to understand what may be blowing this component?
Part number is BTS621L1

Edited by Eamonn-7p1oh on Friday 17th December 16:46

[JHmonaco1973]

Hi Ian, longshot on an old post but you don't have any STP8055 transistors left do you please? got a track day Monday and mine has decided to blow yesterday and after some investigation have traced back to the transistor, happy to cover postage and part. Thanks, Jim