ECU ressurected!

I had my original ECU bite the dust back in '04 and replaced it with a new stock unit, sans Upsolute chip. I saved the old ECU in hopes it could be repaired. When problems first started, the symptom was no boost and DTCs indicated a short or open circuit in the N75 system. As the N75 checked out, it had to be the ECU. I had some success with piping cold air (thermoelectric cooling module)to the ECU but this was only stopgap as it soon failed completely.

Fast forward to yeasterday when I popped the cover and went on a 10x magnification problem hunt. Sure enough, I found the bad solder joint! An SMD diode (freewheeling diode) on the N75 circuit had some soldering flux between the board and device, causing thermal-induced mechanical stress on the solder joint.

Since I don't have any lead-free solder, I "washed" the pads with eutectic SnPb, using a solder vac to remove the junk. Then I was able to use real solder to fix the joint.

After adapting it to the immoblizer and clearing the DTC's (from 2004! talk about non-volitale memory!), I took it out for a test drive. Must remember, PP520s with an original Upsolute program are NOT friendly combination to a stock DMF clutch!

But I am happy. And have a spare stock ECU!

Yes, it smokes.

"No user serviceable parts inside" - HAH!

Good going.

This is a very valuable post! Can you post some pictures? There are probably a few people here who would like to take a crack at ressurecting their old ECU's. Thanks!

Dang it, I installed before snappiing pictures. No, I don't want to crack open the factory spare I now have.

Besides, I don't have a macro lens on my digital.

The best description for the diode location is near the electrical connector block. They look like little cubes of black plastic and have a bar marking on one end. There are a bunch of them, each one is for an output channel to a solenoid actuator. You see, power to such a device is controlled through a MOSFET (type of transistor). When the MOSFET switches off, there is a back EMF as the magnetic field collapses in the solenoid (coil) and a current flows back to the MOSFET. But it is off when this happens and the back EMF would kill the MOSFET. The diode feeds this current back to ground, preventing any back current in the MOSFET.

I will guide anyone through such a repair...or might even offer it as a service to my fellow board members...on a shipping/insurance cost basis. It only takes a few minutes to perform the repair but hours to find as I don't yet have a schematic of the ECU. Yes, I traced it! Not until I had 10x magnification could I see the crack. Thankfully, the cause of the failure being the flux made it most suspect of the group.

I am a self-trained sparkie. My forte is mechanical engineering but plumbing electrons is just as easy as plumbing fluids.

Keith, you're a man of many talents! First you rebuild your engine and now you bring your ecu back to life! What next?

Keith_J said:

I will guide anyone through such a repair...or might even offer it as a service to my fellow board members...on a shipping/insurance cost basis.

Click to expand...

That would be an invaluable service Keith!! You might try getting in touch with jsrmonster (Jeff Roberts) and Kerma (Charlie) and see if they want any reconditioned..? I'm sure there are a few members who need such help.

nicklockard said:

That would be an invaluable service Keith!! You might try getting in touch with jsrmonster (Jeff Roberts) and Kerma (Charlie) and see if they want any reconditioned..? I'm sure there are a few members who need such help.

Click to expand...

Consider it a payback for all the help I got on the rebuild!

dlai said:

Keith, you're a man of many talents! First you rebuild your engine and now you bring your ecu back to life! What next?

Click to expand...

I don't know...let us see...Rebuilt engine + 520PPs + old Upsolute ECU...can you say CLUTCH?

It was fine with just the 520PPs but with the Up? Slips in 4th and 5th at ~2100 RPM and WOT. Smoke isn't bad as I remember with 205s.

The thing I really like is CLEAN OIL. Yeah, it is a bit black but it isn't India Ink black even after 1000 miles. Is that a good sign? FTR, I purged the oil system but didn't wash the block.

Wow, I am not the only one with this failure!

http://forums.tdiclub.com/showthread.php?t=147290

But it appears I am the only one to fix the problem.

Ok, ladies, I pulled it for photos!

Here are the pictures...



Overview of the ECu sans cover. The diode in question is in the upper left corner.



This is where the failed solder joint is. Center of picture. There are 6 and a half small, black rectangular diodes pictured..smallest black rectangles. From the left, the failed solder joint is the second one. Note, there is an open pad where another diode could be placed. This is for another application, like a 1.8T. It is not used.
For repair, this blank offers a "practice area" as it has the lead-free solder which is hard to repair. It doesn't flow and has a higher melting point. It also defies removal via solder wick and is difficult to vacuum. If this were a preforated circuit board, I wouldn't have issues with use of compressed air but surface mount boards have too many potential points where blown solder can hide. Use a vac and "wash" the solder pads with fresh, Sn-Pb eutectic.

Note the corrosion damage from residual flux. Lead-free solder flux can be quite corrosive. The residual flux probably caused failure of the joint as it absorbs humidity and expands, stressing the solder joint.

no macro... eh?

Great job... maybe we can have a southern tx mechanic...

Macro?

alphaseinor said:

no macro... eh?

Great job... maybe we can have a southern tx mechanic...

Click to expand...

And I speak English with just a little Spainish lingo thrown in..


I have a great Nikkor 55mm F2.8 Micro that can focus down to frog's hair. Only I don't have a scanner for 35mm Fuji Velvia.(E6) that rivals the resolution of my Canon digital.

Plus it is a LOT easier to take digitals. And yes, I have been looking at the add-on lenses for my Canon PowerShot.

GoFaster said:

"No user serviceable parts inside" - HAH!

Good going.

Click to expand...

It's important that I point out that just because Keith did it doesn't mean it's a piece of cake for the average gump. When he posts his thread in a few months about removing his own appendix with a dremel tool, cloroseptic spray, a fifth of Irish whiskey, a soldering iron, staple gun, and (of course) duct tape, don't ask for pictures or think about trying it on your own.

This is a guy who wasn't content to do the usual simple mechanical linkage for the senior design project in mechanical engineering. We had to design and build a fully functioning lithium bromide absorption chiller in 1 ton scale. All nickel and stainless. All in 3 months. With no money. Did I mention lithium bromide is hard to find at the local hardware store? Yeah, he's pretty resourceful.

P.S. It actually worked.

Well you can add me to the list of people that have had this problem. I got the five error codes for the J52, N75, N109, N18 and N108 all open or short to ground and the problem was intermittent. I was pulling my hair out until I found this thread. I checked to make sure all were getting power from relay 109 which checked ok. So it had to be the ECU. I solder for a living (check my profile) so I said I can do this, sure enough found a bad solder joint on one of the large circuit chips with lots of leads the one with a Bosch logo on it. Did not want to remove it because of the large number of leads so I just sucked out the old solder the best I could used some rosin flux and leaded solder and now the problem is gone. Thank you so much Keith you saved my ass. Dan

ECU failure?

Hi all, I'm a new TDIClub member (after occasionally lurking for the last couple of years).

My 2000 Jetta TDI has no power and vag-com reports 5 codes -- 17849, 19561, 18027, 17957, 17660.

I read KeithJ's repair http://forums.tdiclub.com/showthread.php?t=178482 with great interest. Today I pulled the ECU but could not see any failed solder joints (unfortunately I did not have a magnifying glass for a 10x inspection, but I spent a good 30 minutes scutinizing every connection as closely as possible).

I am going to replace the 109 relay, just to confirm that's not causing any of the problems. Assuming the new relay does not help, what is the likelihood that my ECU has failed? What is the likelihood that it can be repaired?

Any advice appreciated, thanks!

Replace fuse 34 - red 10amp
;-)

Solved

deek said:

Hi all, I'm a new TDIClub member (after occasionally lurking for the last couple of years).

My 2000 Jetta TDI has no power and vag-com reports 5 codes -- 17849, 19561, 18027, 17957, 17660.

I read KeithJ's repair http://forums.tdiclub.com/showthread.php?t=178482 with great interest. Today I pulled the ECU but could not see any failed solder joints (unfortunately I did not have a magnifying glass for a 10x inspection, but I spent a good 30 minutes scutinizing every connection as closely as possible).

I am going to replace the 109 relay, just to confirm that's not causing any of the problems. Assuming the new relay does not help, what is the likelihood that my ECU has failed? What is the likelihood that it can be repaired?

Any advice appreciated, thanks!

Click to expand...

OK I replaced the 109 relay and power was restored - cleared the codes and they haven't returned. (I suppose it's possible that the problem still relates to the ECU and my 'fiddling' regrounded a broken solder joint -- but for now I'm choosing to believe it was the 109 relay!)

UPDATE: Rats ... CEL just returned with the same codes, guess it's ECU failure after all. I'm going to pull it again and give it a closer look.

Old thread, I know, but hoping someone here might know the source of my problem.

Recently, my 2004 TDI (BEW) had 2 simultaneous problems:

1) Digital read of mileage zeroed out (was about 256k). Continues to correctly accrue miles now, but started over from zero (ie, never reverted to 256k).

2) Cruise control stopped working.

I have the infamous dongle, and have checked all the various CC bits - nothing wrong can be found.

I conclude the problem must be the ECU? Would this be accurate?

Hi Everyone,
I know this is an old thread but I am willing to resurrect it like Keith_J did with his ECU and like a did with mine thanks to his ideas.
I hope it helps others that might have similar problems.

A couple of months ago my B5 started to randomly enter in limp mode due to N75 short to ground or open. At the time I left it on my mechanics workshop for repair and to do the timing belt. It was also leaking fuel from the tandem pump and the turbo was also checked. It came as new without any problems.

After a 1000km the problem came again but that time it was more severe. The diagnostics was throwing a lot of error and at a certain point the engine failed while I was driving. The list of engine errors was the following,

17932 - Fuel Pump Relay (J17)
P1524 - 35-10 - Open or Short to Ground - Intermittent
17849 - EGR Valve (N18)
P1441 - 35-10 - Open Circuit or Short to Ground - Intermittent
19561 - Valve for Intake Manifold Flap (N239)
P3105 - 35-10 - Open or Short to Ground - Intermittent
18027 - Glow Plug Relay (J52)
P1619 - 35-10 - Open or Short to Ground - Intermittent
17957 - Boost Pressure Regulation Valve (N75)
P1549 - 35-10 - Open or Short to Ground - Intermittent


Cleaning all the errors sometimes worked sometimes didn't. After searching for a while I found this thread and decided to open my ECU (I am an Electronics Engineer so it was easy for me to decide).
Going to the finals, I discovered that almost all the pins of my ECU connector had broken solder joint and that is why the problem was intermittent. Below you can see and example



Almost all of these were broken.



To solve the problem I just re-soldered all the pins and so far the problems all gone and I have a clean diagnostics.

If you need anyone need any help with this, just let me know and I will be happy to help!!

Thanks
Pedro

Thanks for bringing this up

http://forums.tdiclub.com/showthread.php?t=491803&highlight=erratic+n75

I ran in to a similar issue, replaced my ecu but kept it. I am too much of a clod to do fine electrical repair and shelved the idea until the time would come. I will show this thread to a friend of mine who is capable, might have some questions for you. Thanks again!

I kind of like what I'm reading here. I have similar problems. Subscribed

I've fixed more than one EDC15 ECU by reflowing these connections.

Sinalux said:

Hi Everyone,
I know this is an old thread but I am willing to resurrect it like Keith_J did with his ECU and like a did with mine thanks to his ideas.
I hope it helps others that might have similar problems.

A couple of months ago my B5 started to randomly enter in limp mode due to N75 short to ground or open. At the time I left it on my mechanics workshop for repair and to do the timing belt. It was also leaking fuel from the tandem pump and the turbo was also checked. It came as new without any problems.

After a 1000km the problem came again but that time it was more severe. The diagnostics was throwing a lot of error and at a certain point the engine failed while I was driving. The list of engine errors was the following,

17932 - Fuel Pump Relay (J17)
P1524 - 35-10 - Open or Short to Ground - Intermittent
17849 - EGR Valve (N18)
P1441 - 35-10 - Open Circuit or Short to Ground - Intermittent
19561 - Valve for Intake Manifold Flap (N239)
P3105 - 35-10 - Open or Short to Ground - Intermittent
18027 - Glow Plug Relay (J52)
P1619 - 35-10 - Open or Short to Ground - Intermittent
17957 - Boost Pressure Regulation Valve (N75)
P1549 - 35-10 - Open or Short to Ground - Intermittent


Cleaning all the errors sometimes worked sometimes didn't. After searching for a while I found this thread and decided to open my ECU (I am an Electronics Engineer so it was easy for me to decide).
Going to the finals, I discovered that almost all the pins of my ECU connector had broken solder joint and that is why the problem was intermittent. Below you can see and example



Almost all of these were broken.



To solve the problem I just re-soldered all the pins and so far the problems all gone and I have a clean diagnostics.

If you need anyone need any help with this, just let me know and I will be happy to help!!

Thanks
Pedro

Click to expand...

My original ECU had cold joints all over the header to board pins. The BD code ECU was much better only a few.

Boost control became better after going over both. The capacitors we're also swole and no good after 20 years.