Thanks michaelh, I already contacted him.

 

Well, found my vcats sticker and the correct ECM for my vehicle is LJA1410CA/010.
This forum is a mother lode of information, digging it out takes some effort.

Here are some photos of the back of the pcb :

 

It got pretty hot. Both covers, top and bottom, are pretty scorched. I'm surprised it didn't catch fire......

 

btw, I don't know anything about 'multi-layer pcb'......

 

The VCATS label is your friend.

If you can strike a deal with XJsc-guy, ask him what's on the donor VCATS for the ECM (I believe he still has the car). If the two match, then it should be a plug 'n play swop.

I'd still get another opinion on the one you have (eternal optimist). They don't make them like that any more.

Good luck & please let us know how you fare.
Mike

 

Within the thickness of the item are several thin layers: metal (copper) alternating with insulation. Signals are routed up and down to reach the right layer / side of the board and connect to the various components.

If burnt enough it could be a swine to fix, sadly.

 

Ok, I've contacted two repair guys and both said it iffy. So I've decided to try and fix it myself. I cleaned it up with alcohol then removed the damaged capacitor. As you can see from the photos, the motherboard around and underneath the capacitor was damaged pretty bad. Some of the board is glued to the capacitor itself. However, I am going to try putting in a new capacitor anyway.

Problem : identifying and finding the correct capacitor. I am not sure if this is a 560 or 5600 because it is so badly burnt. Also, I doubt this is the original capacitor as this ECM was repaired once back in 2014. Also, this is a 105c capacitor which seems harder to find, most are 85c. Last, it is a 50v and 100v seems easier to find.

So, any help in identifying and tracking down the correct capacitor greatly appreciated.

 

Did some more searching on eBay and found a matching capacitor. You have to be careful because some are 18mm high and others are 25mm tall. The 25mm probably won't fit when you put the cover on. Otherwise the one I found is 50v 560 @ 105c.
Now, does this match the original capacitor???

 

Here is the capacitor I found. It appears to be almost identical in both dimensions and capacities:

https://www.mouser.com/ProductDetail...pHYrntHw%3d%3d

 

This is from another thread concerning the same problem. Do a search for #capacitors# and you will find the whole thread. I think it was by Tony Foreman.


Hi,

Yes, Capacitors specs are as follows:-
1 x 560uf, 50V, 105°C
2 x 47uf, 63V, 105°C
2 x 220uf 10V, 105°C
2 x 10uf, 50V, 105°C

By the way, still running without issue 2 weeks on and 300 miles.

Also noted that poor hot engine starting issue has gone away also.
Used to have to start using throttle when hot, (took some cranking)(fine when cold)
Now it starts when hot perfectly.

Tony.

 

" ....storage times can result in a loss of capacitance. In aluminum capacitors, this induces more leakage current, due to the aluminum oxide layer slowly dissolving into the liquid electrolyte. As this happens, the leakage current of the capacitor can be high, especially when it is first energized. As a result, the part may heat up and, in extreme situations, may experience thermal runaway and failure."

Sounds like our ECM. It appears to be an aluminum capacitor that typically fails.

 

I also suspect that little black capacitor on the edge of the burnt circle is damaged as well. Or on its way to failure....

 

Oyster - thanks. Looks like if you are going to replace capacitors you should replace all seven. I'm guessing this is what they call a 'rebuild'....

 

Hi again.

Took out my own ECM for inspection. Everything looked OK.
Tried to take some pictures to show you the numbers on the capacitors, but it was hard to get the camera in position.
It is a small fan below the ECM, something like a computerfan. Be sure this is running with ignition on.
DO NOT turn on ignition with ECM disconnected.

 

Great pics

 

Hi Oyster -

I did turn on the ignition with the ECM removed in order to program my windows so I could close my doors. Ouch?

So, to test the ECM fan you have to plug the ECM in but lifted out of the way enough to observe the fan, correct?

Thanks for the photo. There is a 7th capacitor underneath the upper 1/2 motherboard. You have to loosen it and lift it up to see it. One observation : where you have 4 capacitors in a line, the two middle ones on mine are much smaller than yours (see photo). What are the numbers on your two middle capacitors? The numbers on mine are : 47uf 16v
From the list you helpfully provided it looks like these are supposed to be 47uf 63v !!

 

Hi Mike -

Here are the photos.

 

Hi greenforest56,
It may well be that the cap that has self-destructed was the only one not changed when the last person was in. Shame, as it's not the worst repair ever other than the 'QVS' caps (I don't recognise the brand) don't look particularly good quality and they're underrated temperature-wise, so they do need to go.

The pin marked with X:


is the incoming B+ for the logic, but I can't see where it routes to at the moment. I'll take a look at the new pictures.

Mike

 

Hi again.

Sorry, no more pictures so far. I have put my ECM back in the car.

The ECM is held in place by four small foam blocks (approx. 1x1x1 inches) two on the top and two below.

Your description of checking the small cooling fan is the way I did it.

I don't know if you damage anything by turning on ignition with the ECM out.
I might be paranoid, but I never do anything to the electrics without disconnecting the battery.

For info my car is close to yours VIN-wise, 011729, US specification.

I tend to agree with Mike, someone has been there before doing a lousy repair.

Watching your progress with great interest.

 

Hi Charlie.

Warning: this won't be easy, and may fail. I wouldn't blame you for abandoning the task, so please shout!

Anyway, for starters, here are the pins on the adjacent connector that are affected. I believe we’re only looking at 1 to 6, as the the rear 7-12 are clear of the burnt area. I’ve included them for completeness’ sake. Many of the connections are doubled up (curly brackets).



EM14-1 GY} Throttle motor power relay power in via F9 (30A) engine compartment fusebox
EM14-2 GY} Throttle motor power relay power in via F9 (30A) engine compartment fusebox

EM14-3 WR Ignition II via F10 (5A) engine compartment fusebox
EM14-4 BK Logic ground (EM1BR)

EM14-5 R} Throttle motor
EM14-6 R} Throttle motor

----------------------------------------------


EM14-7 B} Ground (EMS37)
EM14-8 B} Ground (EMS37)

EM14-9 B} Ground (EMS38)
EM14-10 B} Ground (EMS38)

EM14-11 G} Throttle motor
EM14-12 G} Throttle motor


Break this track at the red circle and peel the copper strip back away from the burn. Easiest might be to remove it completely and run a jumper between X and Y.
I’m not sure what ?721 refers to - it could be the burnt cap (the first letter isn’t a ‘T’ or an ‘R’, so probably ‘C’) or, less likely, a small missing component.
It looks like you've removed most of the charred material - the cleaner the better, and particularly between adjacent tracks as the residue could be conductive. Look carefully for any short-circuits.




Next, if this can be cleaned up then it may be OK, otherwise cut the track near X and Y and jumper across.



Last for now:


Oyster’s picture shows the area in the red circle should be mostly copper. It’s probably stuck to the bottom of the cap

Remove the loose copper and run a couple of fairly stout jumpers between the two Xs and pins 1 & 2 of the connector (these pins are bridged). Curve them around where the new cap will sit.

I suspect that the leg of the blue cap (circled yellow) is connected to the copper around it, unlike the other leg. Can you scrape gently around that area to confirm?


Pin 3 is the logic 12V feed via a 5A fuse. I can’t see a connection to the copper either on the top or bottom of the board, so the copper track is probably in an internal layer of the board. It may well be undamaged, but will need some probing with an ohmmeter to be sure.

Pin4 is the logic ground, which I think should head over to the green circle.

A close-up view this area from above taken from an undamaged, even faulty, board would be helpful.

See what you think,
Mike