your ECU is faulty, sir

[SmartWombat]

You don't say ?
Just had to slip this in because it's an understatement.

Took them nearly 3 weeks to diagnose the fault.
After locking up in 6th gear and stalling.
The main dealer replaced the wiring to the gearbox because it was chafed.
But the car refused to start.

The reason is that the ECU wasn't driving the gearbox into Neutral.
Well I could have found that just by listening to it not working

And I've found the fault !

The 3rd driver chip along has got so hot that it has melted the solder holding it on to the circuit board and slipped down to the point where it's not doing anything any more because it's not connected to anything on the circuit board except the heatsink :mad2:

Taken with Rufus' Canon A430 camera-around-the-world, not bad macro when the operator puts his glasses on and gets it in focus, eh?

[natgaines]

Cold-solder joints are a real pain-I'm an electrican, they're the bain of my existance. Does it scare you the specialists couldn't find it? I know that always drives me nuts. The fact that I even have a clue what they're talking about surprises people, mostly because I'm a 100 pound girl, I look like I should be baking a cake.

Nahhh...

[SmartWombat]

Cold joints?
Not this one.
There was a fault in the wiring to the clutch actuator/gearbox motor.
They never told me what it was and the just spliced in some new wire to fix it.
Assuming it was a dead short, that was pretty good not to go up in smoke...
Now my challenge is to identify it, there's a lot of different D2Pak components !

I'm pretty sure it's not an intelligent power MOSFET, because those have thermal shutdown at 165C.


A friend's car with the same ECU model turned into a smoke-emitting device and stopped providing fuel to cylinder 2. His problem was further back in the chain with a 4-pack low current driver blowing a hole in the package.

[Jaedon]

(read the following with the intended sarcasm) There's the problem right there SW. You let the smoke out. Electronic things do not work well once you let the smoke out. It is apparently a very integral part of their construction =P

[SmartWombat]

Ah yes, the LUCAS pressurised smoke theory of car electrics.

[r_w]

The FET doesn't really even look damaged. If it is a thermally protected FET, it probably got hot enough to melt the solder and that is about it. Reflow it back on and it may work. Though if you can read the part number it might be an easy one to get...

[freygr]

I would unsolder it and do a VOM function test on it before reinstalling the transistor or FET. Unluckily the AC302 is a lot number. So the part number may be the number along the tab, which I can't read in the photo. But it looks like all the D2Paks are the same part.

[SmartWombat]

Well they seem to me all mosfets, and the only D2Pak I can find in catalogues are from International Rectifier. But these have none of the proper identifying marks.
I'll probably send it out to a specialist.
Or go borrow a copy of Towers and see if I can identify it.