1986 325 3 pin plug by ecu

Post Fri May 27, 2011 10:36 pm

right i have gone today and bought all these parts and nothing still !

so i think its something to do with the 3 pin plug via the ecu as nobody has an answer to what it really does !

ecu
coil
leads
rotor arm
dizzy cap

so why is it still not sparking ? i have checked everything every one has stated ! i have checked all volts, all earths, relays, and nothing is making a difference ! if i cant get it going by the weekend im just going to weigh it in !

Post Fri May 27, 2011 10:53 pm

White plug? Sends fuel rate and engine speed info to clocks, does not affect running at all

Post Fri May 27, 2011 11:08 pm

ok so i have spliced the yellow and the black into the loom but what does the green feed to then ? any green or a set green ?

so why wont the car run ? nobody seems to have an answer ? same for me and moody

i have checked every thing possible from the ecu to sensors to checking volts but no running engine yet !

cheers for the reply dude

Post Fri May 27, 2011 11:15 pm

its 1986 so whats the green live for then ? and yep that plug

so can anyone actually understand why my car dont run ??

cheers dom

Post Fri May 27, 2011 11:58 pm

The only connections the engine loom needs for the engine to run is battery+, battery - (earth), and the plain green and green/purple in the 20 pin engine loom plug. Green is 12 volts + in from the ignition switch, and green/purple is 12 volts back out again, heading for the fuel pump.
The black/yellow from the start position of the ignition switch to the starter motor also needs to be connected just to start the engine.
We can't understand why your car doesn't run from here, because we can't see and touch it. Only you can do that.
Can you update us please:
Do you have sparks at the plugs when the engine is cranked?
Does the fuel pump run when the engine is cranked?
Does the fuel pump run when you bridge 30 and 87 of the fuel pump relay?
Does the DME relay click when you switch on the ignition?
Is there 12 volts between the + terminal of the ignition coil and earth (checked with a bulb) when the ignition is on and when the engine is cranked?

Post Sat May 28, 2011 9:36 am

We can't understand why your car doesn't run from here, because we can't see and touch it. Only you can do that.
Can you update us please:

Do you have sparks at the plugs when the engine is cranked? no spark

Does the fuel pump run when the engine is cranked? No the fuel pump is not cranking when I cranl the engine

Does the fuel pump run when you bridge 30 and 87 of the fuel pump relay? yes it does

Does the DME relay click when you switch on the ignition? No its not clicking any more but it used to and I have just tried a new relay

Is there 12 volts between the + terminal of the ignition coil and earth (checked with a bulb)
when the ignition is on and when the engine is cranked? when ignition is on yes when cranked will check in a little while

thanks brian

i will bung a drink if any one can help me fire this up as im almost finished with my car to a really nice one off car and i dont want to lose ! im on a winner once this is up and running

cheers dom

Post Sat May 28, 2011 12:30 pm

Just bridged that green wire from that 3 wire plug and she runs !!!!!!!!

Post Sat May 28, 2011 5:39 pm

Sounds like your problem is with the green wire that passes through pin 7 of the C101 engine loom plug and comes from the ignition switch. You are now back feeding power into the loom through a plug where it should be coming out.
Not consistent with having power on the ignition coil + terminal though, as in the last batch of tests.

Post Sat May 28, 2011 5:53 pm

So what will be the problem then if I leave it ? As its running fine and all works as it should

Post Sat May 28, 2011 6:23 pm

"bridged that green wire" to what?

Post Sat May 28, 2011 6:31 pm

A green wire from the loom behind the dash

Post Sat May 28, 2011 6:41 pm

The problem with leaving it has you have done is that you are feeding power in by a very small wire, instead of the bigger wire it should be.
Take the C101 plug and socket apart, and connect your bulb between pin 13 on the car body side (loom comes from the fusebox) and earth, and see if it lights with the ignition on. This is where the green ignition supply should come from.

Post Sat May 28, 2011 8:12 pm

ok i will do that and i also fed a nice size cable to it so should be ok but i will try to find the correct way for this but im so glad to hear something ! after all i have been through with this i was close to scrapping it !!!!

Post Sat May 28, 2011 8:35 pm

The wire you've used for the jump may be a decent gauge, but it connects to a very small wire from the three pin plug, which is the one that matters! There's also the possibility of two live loose ends floating around somewhere, that should be joined together.
If you want a real wiring nightmare, I've just had an E36 delivered here that has been attacked by its total muppet previous owner with a pair of side cutters, loads of insulating tape, and a soldering iron. Local garage, where he took it, had a go at it, then shipped it off to the BMW dealer, who relieved the owner of £500 before giving up on it, returned it to the garage who connected the battery and promptly disconnected it again when smoke poured from the boot, and now it's my turn!

Post Sat May 28, 2011 8:38 pm

ah shit ! well i will source the correct feed but now its got me further to now know its to do with that green feed ! so im closer than before haha

Post Sat May 28, 2011 10:10 pm

Brianmoooore wrote:"bridged that green wire" to what?

this ^^

any pics Dominic ?

Post Sat May 28, 2011 10:14 pm

Right! I think I've finally cracked this.
I've found an ancient pre pre facelift version of a 325 wiring diagram that appears to match up with what you describe. Older than anything I've ever dealt with!
The 3 pin plug is the C104, and should have a black, a white, and a green wire.
The black is the feed for the rev counter, and in your body loom will be a black wire on pin 9 of the C101 by the fusebox.
The white is the fuel rate signal, and needs to connect to the white/black on pin 8 of your C101, and the green is the ignition switched live to the DME relay.
On all the E30s I'm familiar with, the DME relay is controlled by the engine ECU, but in yours it's switched directly by the ignition switch, and contrary to what I've said above, the supply to this doesn't go through the C101.
In the donor car for the engine there should be a 29 pin C103 plug and socket behind the glovebox which supplied all three connections to your C104, including a green from the wire connected to the green wire that goes along behind the dash. Basically, you've solved it yourself, and it appears that it's correct to connect this green wire in the C104 to the green wire that comes from the ignition switch, preferably after the plug and socket clipped to the steering column, but any plain green will do.

Post Sat May 28, 2011 10:25 pm

this is quite an interesting thread for a sad barsteward like me,

I have this week fitted an early 86' H/C engine complete with early management loom/ ecu into a facelift 91' turd,

I haven't looked into it deeply yet,
she's all plumbed in but there's no starter action ?
as mentioned earlier in this thread there's no Ground on the early engine looms that normally goes to the turret ?

Post Sat May 28, 2011 10:32 pm

nope the earth steve is on the manifold right under the service plug ! so tap the green thats on the 3 wire plug by the ecu into a green wire in the loom behind the stereo and you will have it running dude.

also thanks for confirming this brian, i new there was something wrong as moody stated that there was a live there and it got me thinking straight away. also nicked a plug from an early cab and spliced it in myself.

so the 3 yellow/white do i just cut that by the clocks and feed it from my ecu ? or shall i just splice it into the wire ? same with the black ? as i dont want to completely cut them off and find its wrong. thanks a bunch brian live saver !!!

im so happy i got it right and running cheers fella's

Post Sat May 28, 2011 10:34 pm

e30topless wrote: she's all plumbed in but there's no starter action ?
as mentioned earlier in this thread there's no Ground on the early engine looms that normally goes to the turret ?

No, apparently they're all on the inlet manifold.
No starter action should be simple enough to solve. Start by linking 11 and 14 on the diagnostic socket, which should engage the starter.

Post Sat May 28, 2011 10:46 pm

The black and white/black that you need to connect to the C104 are in the loom that goes right past this area, on their way to pin 7 of the blue instrument cluster plug (black wire) and pin 11 of the same plug, but it's changed to a yellow/white wire by the time it gets here.
You can curt and splice into them in the loom here, if you can identify the correct wires.

Post Sat May 28, 2011 10:47 pm

will have a look cheers brian, never thought of bridging 11 and 14

normally I would fit 1.3 to a facelift as BMW intended !

Post Sat May 28, 2011 10:49 pm

Well at least we know what that green wire is for now

For years ive always thought WTF is that green wire doing there

Post Sat May 28, 2011 11:01 pm

i have hold of the wires already as the plug on the other side that you have to cut from the early interior loom has the correct colours already so i dont know weather to cut them and join my 2 wires to them or splice them in

Post Sat May 28, 2011 11:12 pm

Probably better to splice them, so that the two pins in the C101 stay 'live'. They will then work if you ever upgrade your management system to the much more advanced M1.3.
As fitted by BMW, the best M20 325 engine comes with the worst management, and vice versa.