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BMW E30 325 1990 - Wiring diagram for injectors - Fixed #

Posted by Tony Lewis on November 12, 2018, 6:18 pm

Year of Manufacture: 1990
( Optional ) Engine Code or CC: M20B25

Fault is crank non start. Good RPM Signal,fuel pressure and spark. Will run with a good old sniff of easy start so mechanically ok. Noid lights show no injector signal and there is power to injectors so not being switched by ECU. I have checked the loom under the manifold and this seems ok.

Can anyone help me out with a wiring diagram or pin configuration so I can pin it out and check the wiring from the ECU please.

ECU has been tested and is said to be ok.

Re: BMW E30 325 wiring diagram for injectors

Posted by David Davies <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5218' width='330' height='300' border=0 style='border:none;'> on November 12, 2018, 10:22 pm, in reply to "BMW E30 325 wiring diagram for injectors"
David Davies

Pins 16 and 17 are the injector switching lines from the ECU mounted below instrument panel.Pin16 is for injectors 1,3,5 pin 17 is for 2,4,6.

Re: BMW E30 325 wiring diagram for injectors

Posted by andrew young <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5148' width='330' height='300' border=0 style='border:none;'> on November 13, 2018, 8:24 am, in reply to "Re: BMW E30 325 wiring diagram for injectors"
Andrew Young

I guess this is running Bosch Motronic with an 88 pin ecu. Not much to go wrong on these,but I would check the efi earth points on the head.Also ,if there is no injection signal,the system could be in "clear flood mode", so disconnect throttle switch.

Re: BMW E30 325 wiring diagram for injectors

Posted by Tony Lewis <iframe src='https://members4.boardhost.com/ukautotalk/info/user=ukat3975' width='330' height='300' border=0 style='border:none;'> on November 13, 2018, 8:25 am, in reply to "Re: BMW E30 325 wiring diagram for injectors"
Tony Lewis

Thanks David, I was unable to find info so that's a great help.

Re: BMW E30 325 wiring diagram for injectors

Posted by Tony Lewis <iframe src='https://members4.boardhost.com/ukautotalk/info/user=ukat3975' width='330' height='300' border=0 style='border:none;'> on November 13, 2018, 11:25 am, in reply to "Re: BMW E30 325 wiring diagram for injectors"

I have continuity from pins 16 and 17 to injectors and I can manually signal the injectors on. I've tried disconnecting the throttle switch but I still don't get an injector signal. Something that looks a little strange is pins 35 and 36 (purple/grey and black grey) coming out of the ecu have been spliced in to pin 37 (Red/blue)???

Where are the earth points on the head which you mentioned Andrew?

Thanks

Re: BMW E30 325 wiring diagram for injectors

Posted by andrew young <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5148' width='330' height='300' border=0 style='border:none;'> on November 13, 2018, 8:51 pm, in reply to "Re: BMW E30 325 wiring diagram for injectors"
Andrew Young

If you have a good spark and fuel pressure,power to the injectors,I can't see any reason for no injector pulse other than an ecu fault. Is the splice an original feature? The earth points (from memory) are near the front of the engine,near thermostat housing.

Re: BMW E30 325 wiring diagram for injectors

Posted by David Davies <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5218' width='330' height='300' border=0 style='border:none;'> on November 13, 2018, 10:38 pm, in reply to "Re: BMW E30 325 wiring diagram for injectors"
David Davies

Pin35 should be NBV ignition on. Pin36 earths the coil of the main relay.Pin 37 receives power from the main relay,when the relay is switched by pin 36. I'm guessing feeding power to terminal 36 may have damaged ECU. I would remove this wiring 'bodge' and fit another ECU as they are available quite reasonably and no coding/immobiliser to deal with.

Re: BMW E30 325 wiring diagram for injectors

Posted by Tony Lewis <iframe src='https://members4.boardhost.com/ukautotalk/info/user=ukat3975' width='330' height='300' border=0 style='border:none;'> on November 14, 2018, 3:04 pm, in reply to "Re: BMW E30 325 wiring diagram for injectors"
Tony Lewis

Just got back on to this and realised I made a MASSIVE schoolboy error and counted the pins the wrong way!!!!

pins 40 and 41 have been joined into pin 37

Fixed #

Posted by Tony Lewis on December 3, 2018, 9:47 am, in reply to "Re: BMW E30 325 wiring diagram for injectors"
Edited by board administrator December 11, 2018, 1:50 pm

Fixed!
Just to update, I sourced a 2nd hand ECU and plugged in this morning and it fired straight up, despite AC tronics testing the original ECU as being ok.
Still not sure why pins 40 & 41 have been spliced into pin 37 but it runs.
Thanks for the help.

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