mojorizing

Based on the pics from earlier, I agree with Barryn. You had the face plate off at some point, correct? and a sharp bend of the ribbon cable could short out on something sharp, like the metal chassis,etc.

Please take some photos of the damaged boards when possible.

mojorizing

If you don't mind....who did the repair, and how much $$$?

gmorat

The faceplate was never off as far as I know as it was my impression that it was a new unit which was fitted just before I bought the car.

The original unit had some minor issues but the guy was trying to get rid of the car in a timeframe so sending it out for repair wasn't an option.

It's possible the unit was rebuilt but I don't really think so as it has a 2012 date stamp on it. Maybe it was just a flaw in the ribbon connector. Thats my fervent hope at the moment.

G

I'll PM you about the price.

gmorat

Here ya go. No sharp bends in the ribbon cable.

ToreB

Wow. The ribbon cable is not the culprit, it was only to be in the area of destruction. I maintain my theory that this is a component failure on the front PCB, but it might be a PCB track that have been exposed to excessive current too. There must have been a LOT of current there to create such a damage. You are lucky that the CCU didn't caught fire.
I'll have a look on the front PCB layout to see what this could have been. Have the repairman given you any clues of what might have caused this?
Don't throw away the PCB's, they still has some value as spare parts.
Cheers,
Tore

gmorat

They didn't, just do not plug it back in without 'testing' the system. Not sure what to do next. Certainly will not be plugging it in any time soon.

G

gmorat

Few more shots if the center if the damage as well as the reverse side.

mojorizing

Good pictures
Looks now to be on me of the surface mount components on the display board.
I'll look at mine when I get a chance - I have one apart.

gmorat

What about the grounds? Could they cause a problem like this if dirty/missing/not connected properly?

gmorat

Somebody was asking me about the CCU issues and he mentioned this....

Water damage will do what happened to your CCU board & ribbon cable. I wonder if there was water present where anywhere in the fan circuit. Was it raining exceptionally hard when the CCU burnt out? Were any repairs done (like windshield replacement)?[

My car hit a pedestrian in 06 and the bonnet and windshield were replaced. Do you think this could be an issue? I wonder how to check and then guard against it happening again.

G

ToreB

Here's a pic of a fresh CCU front PCB. This section controls the switch illumination LED's. There's +12V and GND involved, and it seems that one of the transistors initially has given up the ghost. However, the extent of damage might indicate that water have done this.
Cheers,
Tore

gmorat

Obviously you mean water somewhere else could have caused this as there's no way that this got wet.

Time to pull out the hose me thinks.

G

gmorat

Update.....

Electrical system has been checked for shorts and there are none.

Car was left out in a NC thunderstorm to check for leaks and there were none nor evidence of prior leaks.

7.5amp fuse was swapped for a 3amp fuse and battery was disconnected.

Rebuilt CCU was installed back into car and battery was reconnected.

Started the test cycle from Tore's website.

Fan and temp dials seem to work.

Sliders seem to control servos as they should, air comes from where it should based on the position of the sliders.

Haven't pressed any of the 4 buttons yet. I will when I have a little assistance to watch the draw on the fuse as I turn on and off these feature.

I'm a little apprehensive as if it happens again its a lot of money and the pressing of the defrost button is what seemed to kick this all off over 2 months ago.

G

mojorizing

I've looked at my spare CCU and the circuit is different than yours - in that area are 2 smt transistors and only 3 smt resistors. It's the two button snow flake with version B10003/7 display pcb.

Anyway, if your problem is associated with the backlighting circuit, realize that each button should light up when pushed in, and the back light bulbs behind the fan speed and temp ***** light up when your headlights are on.

Did you happen to verify the correct bulbs is in the display?

ToreB

Congrats gmorat! You've done a fantastic job testing your wiring and ventilation components.

There's several versions of the front PCB's, older versions have even through-hole type of components. The transistors are involved in the indicators inside the buttons only, and not the backlighting bulbs.
I guess the engineers planned for a more sophisticated function of the little yellow lights when they made the CCU. In practice, they are only indicators for a pressed button.

You have ruled out all other possible causes of this, and we are left with two:
You probably either had a short circuit due to mechanical reasons inside the ccu, (induced by pressing the button) or a catastrophic component failure of one of the SMD transistors on the front PCB.
Judging by the extent of the damage, you were lucky it didn't really catch fire.
Cheers,
Tore