E34 Transfer case electronics

[turk]

Can anybody tel me anything about how they work. I hear its "lock" is controlled by the ABS system, it uses the abs sensors to determine the lock %

What I need to know is how to replicate this. Can I make my own circuitry some how to fool it to run in an e30? It does have abs so don't know if i could piggy back off the e30 abs electronics.

Can the ecu be tweaked to make the "lock-up" work?

Cheers
Turk

[kam-325i]

The E34 system exists in 2 generations with a major difference:

Generation 1 has separate control unit which control electromagnetic semi-wet multiplate disk clutch in centre and electrohydraulic wet rear differential. It recieves ABS wheel sensors data signals from special, modified ABS unit. Front differential open. In production from april 1991 up to september 1993.

Generation 2 has ABS/ASC+T unit which controls semi-wet electromagnetic multiplate disk clutch in centre and an open differential rear through rear wheels brakes (ABD). It also controls throttle. Front differential open. In production from October 1993 up to end of production.

[turk]

There is a 2 pin electrical connector on the case. I have no idea what year case this came off of.

I can't be as easy as 2 positives and earth to lock this bad boy up can it?

Heres a pic hoping you can tell me

[kam-325i]

Electromagnetic will be just On or Off......like the electromagnetic clutch on an AC compressor.

You could control the slip of the clutch by varying the power to the magnet or magnets.....

[turk]

so presumably a 1v to 12v feed to the pins?

Should it be a positive to each pin and ground to the box? or + to one pin and - to the other?

Do u have any data on it like pdf's, wiring diagram or anything?

Many thanks for your help too btw!

[Speedtouch]

http://www.autolib.diakom.ru/CAR/BMW/19 ... MS/294.pdf

There are other diagrams for other years and models - I just entered 1993 525i.

Enter your own choice at http://www.autolib.diakom.ru/CAR/BMW/

[kam-325i]

try here, under slip control

http://www.armchair.mb.ca/~dave/BMW/e34/e34_94.pdf

[turk]

can't spot the transfer case switch in either of those links

[kam-325i]

can't spot the transfer case switch in either of those links

what you see on the centre transfer case is a plug, not a switch.

[turk]

Sorry, yes plug is what I meant.

Is it the "front power distribution box" As there are two i can spot on the slip diagrams?

[Speedtouch]

It would help us if you could tell us what the part number is, and what model it's off; this can then be put into RealOEM to get the exact name of the part you're referring to.

[turk]

I will get the part numbers tomorrow, No idea what year its off unfortunately.

It is a transfer case for an e34 525ix, I'm assuming earlier model with electromagnetic switch as there is only a 2 pin plug.

[Speedtouch]

I'd imagine that plug powers a solenoid (electromagnetic coil) to move a clutch in and out.

This could be verified by using a multimeter to measure the resistance between the terminals, which should be at least a few ohms.

You then probably just need to wire up a +12V and ground to its two pins. The trick is to get them the right way round, to achieve the correct operation.

However, if it is a simple coil then no harm should result connecting it the wrong way round.

[turk]

However, if it is a simple coil then no harm should result connecting it the wrong way round.

This is what worries me. i don't want to phuck up a perfectly good Tcase as they are harder than rocking horse shit to find.

I will do the multimeter test tonight and let you know the result.

I can see the plug has a slight rivet so it must be pole specific. Just need a pic of someones plug to determine which way round to have it.

[turk]

OK, Continuity check confirms the 2 pins are defo connected. Ohms, was all over the place the for the first second and then settle on zero.

There are 3 stubs on the outer side of the plug These also have continuity between one another, and look like they're designed to hold a circular, metal clipped plug.

What I need is someone to post a picture of some e34 plugs with cabling on so I can attempt to lock the basterd up! There is a part number on the actual plug but cannot for the life of me read it.

One of the numbers on the tcase near the output shaft to the front diff.


Gearbox casing no nr bellhousing on the e34 box


Part no on rear on Tcase

[Speedtouch]

The three prongs will be the earthing connection for the cable outer 'sheath' that gives noise protection.

I forgot to mention earlier, try the multimeter resistance check on the 2 pins both ways round. If you get the same reading both ways, then it indicates an unpolarised component, e.g., a solenoid coil. A significantly higher or infinite resistance reading one way round indicates a polarised (semiconductor) part.

Then, try applying a voltage across them. I'd suggest 6 Volts at first, then progress to 12V from a car battery charger or lab power supply, briefly applied then released. You should be able to hear it engaging/disengaging something inside the transfer box.

[turk]

I have tried the multimeter both ways on the pins, either way round the same thing happens:

At point of contact the screen jumps up to 0.876 (ish) then 0.324(ish) and down to zero.
All this happens in a flash, blink and its back to zero...

What does this mean?

Shall i chuck some voltage thru it and see what happens? Does the above mean it is or isn't pole specific?

cheers
Turk

[Speedtouch]

I'm guessing that's due to the reluctance of the solenoid coil, though I would expect it to have at least some impedance (ohms) when the reading settles - what multimeter setting did you have it on, e.g., 0-20 ohms / 0-200 ohms / 0-2000 ohms, etc.?

If you get the same readings both ways round, this indicates it is non-polarity conscious.

[turk]

How do i reduce the voltage from a 12v battery to say 6 volts? Can i wire in a light dimmer for test purposes?

[Speedtouch]

You could wire a 6V lamp in series with it. Use a large wattage one, or it will blow.

What sort of lamp dimmer are you proposing? The dashboard light dimmer will probably be OK.

[turk]

I was gonna rig up a potentiometer dimmer switch into the positive feed and test the output with the multimeter before applying to the pins.

I had the multimeter on 2k ohm setting.

[Speedtouch]

Try the multimeter on a lower setting. I'd expect a biggish solenoid to be in the region of perhaps 4-8 ohms or so, similar to a loudspeaker.

[turk]

sorry, wrong again It was on 2m no 2k. Definitely showed nothing when it settled.

[Brianmoooore]

2m? As in 2 megaohms? If so, I'm not surprised it read zero!
Get it a on the lowest range the meter has, which will probably be 200 ohms on a cheap hobby type meter, or 20 ohms on a better one.
Connect a 21W indicator bulb in series with your 12 volt supply to limit current to the presumed solenoid.

[Speedtouch]

Well, that is a very high resistance setting. On a 2 Megohm range, assuming a 3.5-digit display, anything reading less than 0.001 (1 kilohm/ 1,000 ohms) will show as 0.

Most coils measure well under 100 ohms, as it is essentially just a length of wire wound up, so use the 0-200 ohm, or even 0-20 ohm range.

[turk]

This is what I'm using. I have only ever used it for voltage and continuity. No idea what the rest does.

What seem tying should I have it on

[Brianmoooore]

200 - the one right at the bottom.

[turk]

Lol I will try again then

[turk]

ok, re did it, 1.6 upon first touch, then drops to 0.001
this happens both ways round!

what does this mean?

[kam-325i]

ok, re did it, 1.6 upon first touch, then drops to 0.001
this happens both ways round!

what does this mean?

Sounds like the readings you would get from a coil....

i would guess that there is a solinoid behind the connector....

[turk]

can I cause ant damage by connecting the pins the wrong way round?

[kam-325i]

can I cause ant damage by connecting the pins the wrong way round?

if its a coil in a solinoid, you should hear a kinda click or thud sound when power applied.....

i cant say if you can cause damage or not, as i dont know 100%.

[Speedtouch]

If it's that low a reading, it will be a very low impedance solenoid, i.e., one with hefty coil windings made of thick gauge wire, so unlikely to be damaged by connecting it either way round.

And you certainly won't be damaging any ants in the process, unless you happen to step on one!