Laurence Gibbs

Transistor should have a package number i.e. to92 and a diagram to go with package number obtain from supplier or to establish by reading, a transistor is basically two diodes with there legs joined at one end and open at the other. For npn the base-emmiter diode goes anode to cathode (red lead to black lead) lowish ohms forward biased i.e. red lead on anode black on cathode. collector to emitter should be open circuit. And base to collector will be opposite of base to emmiter readings . So first establish which two leads read OC(they are Emmiter and collector) then place black meter lead on one, collector or emmiter. To tell if your black lead is on emmiter place red lead on the base (the only other lead) if you get low ohms reading it's the emmiter if you get high ohms /open circuit it's the collector and vice versa. Hope this makes sense!

pncarrerars

Thanks Laurence. Its to92 but don't know manufacturer. It was when I looked for data sheets I found that some are c-b-e some are e-b-c. There are no markings except C33716 W63 & no dot etc. The center pin (base) is offset away from the flat side of the package though. Does this offset ensure that it can only be fitted the correct way round? I tried your check from the previous post & found red lead on base black on other 2 pins gives the same reading for both!

andrew911

Wow- I paid Otto's of Venice to "update" my CCU- I think it was $325....they probably did the stuff you guys did. I'm not an electrical engineer, but after reading this thread, I'd say it was the best money I spent just not having to deal with all of this and spending all the time But of course many on this board are much smarter than me with the technicals and I enjoy reading about this stuff nonetheless....My guess is that also many of you feel challenged to fix things yourself for the satisfaction and knowledge of how everything works

Laurence Gibbs

Sorry Pete was doing from faded memory. Have just checked a similar transistor and indeed they read the same way. Think you will need the manufacturers pin out. Try www.farnell.co.uk or www.rs.com they may have an online database.

robbed666

Hi Pete this might help, I know not all have the same pinout, but the bulk do. If you get stuck I have drawer full at work. 'Pm' me your address and I'll post you some.

P.s Laurence the link to RS components is www.rswww.com

Toddimus

I found the wiring diagram for the BC337 on digikey.com. There seem to be different versions of the BC337, with a dash number following -16 -25 and -40. All of these seemed to have the same pinout if I remember correctly. I think the difference between these variants are the hfe (~gain) of the transistor. Since I think the transistor is used as a switch, the gain doesn't really matter. It's not used in a proportional sense, where the hfe would matter. It's either all on or all off.

Another note, that I forgot if I had previously mentioned... There's an "E" silkscreened onto the board next to a pin of the transistor, which I assume refers to emitter position.

I didn't mean to make this whole fix seem more complicated than it really is, but it's a nuance that could rain on your parade if you don't get it right.

Since the parts aren't expensive, I'd suggest you go get something that you know exactly what it is.

Just my thoughts, and good luck to you.

pncarrerars

Thanks all. Final question, will it cause any damage if I use a replacement part with the wrong pinout or will it just not work? The base will always be correct I think just e & c might be swapped?

Unfortunatly I am too busy with other things to get the ccu out of the car at the moment so I am just preparing the way.

Pete

mwildt

Hi,

I also have experienced a battery drain issue, for a while now. Never gotten around to truely track it down other than it's related to Fuse 1. Yeah I know I'm guilty of putting it off for way too long time, but AC/ventilation doesn't come to mind when I hear the flat 6.

A good friend have lent me a spare fan for the CCU, but I haven't tried it yet. I do however know that mine doesn't appear to be running if ignition is off. Not sure if I first have to take it on a test drive before concluding if that is needed first though.

In any case the T1 fix seems interesting, but I doubt it'll fix my issue, assuming the transistor is driving the fan. Anyone have a diagram for these things or can give other ideas on what to check, besides doing the 'hammer' check.

Thanks,
Michael

Toddimus

@pncarreras -- if the collector and emitter pins are swapped (like the were with my 2n4401), you just put them in the correct way, and you're all set. For me, the flat face on the transistor TO-92 package had to be swapped in the way it faced.

The BC337 original part's flat face, faces away from the relay on the board, while the flat face on my 2n4401 faces towards the relay.

@mwildt -- I think the transistor drives the relay magnetic switch coil. I could be wrong on that, but the way I explained it to myself was that the transistor provides a ground path to the relay coil when it switches on. The failure mode of the transistor was to short the emitter to ground, allowing the relay coil to be always energized, keeping the CCU constantly powered, thereby always running the little fan to check what the temperature of the cabin is.

Do the lights on your CCU buttons still light up with the keys out after sitting for more than 20 minutes? If it's cold, then they should just always be off. I'm wondering if you have the same problem as I did, and additionally your little fan happens to be dysfunctional. You're glad your buddy has one you can try!

The thing about the fan running for 20 minutes is a feature, not a bug. It checks the temperature to see if the car keeps heating up on a hot day so it can turn on the rear blower fan to cool the engine. I think it's actually reading the NTC temperature sensor mounted in the rear blower duct. The CCU is powered to enable this, and the little fan on the CCU always runs when the CCU is powered.

mwildt

Hi Toddimus,

Thanks for the reply. To answer your question, no I do not see any lights in the CCU buttons after the keys has been removed. Though I'll check it again just to be sure. Weather sucks the next couple of days so I may postpone a potential test drive to get the temp to change. In any case I'll pull the CCU check the fan as a start. Could be that both the fan and the transistor is busted.

Thanks
Michael

mwildt

Ohh, forgot to add that when Fuse 1 is inserted you clearly hear the servo motors getting energized. So the CCU is definitely going more 'on' even with the key off.

Michael

JDD

Thanks so much Toddimus. This worked like a charm for me...