C20XE into Mini ECU help

[cooper_mark]

i've dropped a c20xe from a 92 calibra running Motronic 2.5 into my mini
having a problem with the fuel pump priming when the hazzards are on
then on trouble shooting if i put the tester from the ecu casing to the body i'm getting 3.3v....
which inturn put a wire from the ecu casing to an earth the fuel pump relays click like mad.....take the wire away and all is fine......
should the ecu be earthed or kept away from metal...???

[MSG]

As far as i know, all ecu casings should never have a live voltage on them, they should be at earth potential, it seems like one of your earths is not connected and that part is conneceted to the ecu case hence the ecu should be at earth potential, you do need the ecu case to be at earth potential, once you have done this, you then need to find out why your fuel pump relay is going mad.


The ecu case should have been earthed through what might be your missing earth, and by earthing the ecu case directly with a new run of wire, you are effectively making up for that lost earth which should have been supplied to one of the pins of the ecu, this pin possibly connects to the ecu case internally, look up in Haynes manual circuit and ensure all pins shown as earthed are getting earth on them, buzz each pin out that should be earthed, remove battery +ve terminal first when buzzing. (buzz means use an ohm meter and try and read as close to zero ohms as pos with one lead of your multimeter placed on a solid good earth ppoint)


once you done that, you then need to find out why your relay is clicking on...is your relay clattering or just coming on and latching on?)

and as well as why your hazards are conflicting with your FPR, the two circuits should be totally indepenedent.

[cooper_mark]

As far as i know, all ecu casings should never have a live voltage on them, they should be at earth potential, it seems like one of your earths is not connected and that part is conneceted to the ecu case hence the ecu should be at earth potential, you do need the ecu case to be at earth potential, once you have done this, you then need to find out why your fuel pump relay is going mad.


The ecu case should have been earthed through what might be your missing earth, and by earthing the ecu case directly with a new run of wire, you are effectively making up for that lost earth which should have been supplied to one of the pins of the ecu, this pin possibly connects to the ecu case internally, look up in Haynes manual circuit and ensure all pins shown as earthed are getting earth on them, buzz each pin out that should be earthed, remove battery +ve terminal first when buzzing. (buzz means use an ohm meter and try and read as close to zero ohms as pos with one lead of your multimeter placed on a solid good earth ppoint)


once you done that, you then need to find out why your relay is clicking on...is your relay clattering or just coming on and latching on?)

and as well as why your hazards are conflicting with your FPR, the two circuits should be totally indepenedent.

ok thanx
it clatters if the fuel rail earths are removed but when re earthed it clicks and primes the pump each time the hazzards flash

[MSG]

Clattering of a relay is a clear sign that an earth is missing and return currents are flowing through other circuits such as the FPR, and when that happens the relay energises switching on other circuits, which in turn somehow breaks the return path of the earthing current and this then drops off the relay and so on, the clattering cycle goes on indefinite until something will eventually get destroyed, so ensure your fuel rails obviously need to be earthed, that is where your main earths are for the ecu i guess, and like wise the ecu case should not have any voltage on its case, the FPR should come on initially for a brief period to prime the injection rail, when you first switch the ignition on, if it does not, then in the least try and see if it comes on when you are cranking the engine, as during cranking it should be on to supply the necessary fuel to the injection rail, and once the engine has fired it will remain on or rather it should remain on. The relay should drop off when an engine has stalled for safety.

[Andy K]

whats making your hazzards flash. Is it the alarm ?

Check the alarm and imboliser connections. Maybe you have 2 wires mixed up on the alarm. Indicators and imboliser

[cooper_mark]

been doin a little more digging today and found this.....there was a ring terminal on the end and was broken
brown/grey i think.....with cooper wire outter and covered with a black sheaf....
how do i reconnect this......do both the wires join together on the ring terminal or just the inner one.........???

[corsacraig55]

Is that to the back orlf the fuel rail if so its an earth notvery clear from the photo

[cooper_mark]

Is that to the back orlf the fuel rail if so its an earth notvery clear from the photo

yeh it's an earth this is it

[Rocksie801]

Check the alarm and imboliser connections. Maybe you have 2 wires mixed up on the alarm. Indicators and imboliser.

[cooper_mark]

no alarm on it

[vectra640]

where are those wires on your loom, what are they near, the brown is normally earth and what looks like black would be +, but tell us where on the loom these wires are and we can shed more light on it, also what sort of gauge are the wires (roughly), are they on the 2.0ne loom or your car loom?

[cooper_mark]

the wire is on the c20xe loom on the left as ur looking in the engine bay from the front of the car
looks like a brown/grey or white and it had a ring terminal on the end..

[vectra640]

ok bare with me

[cooper_mark]

ok cool

[vectra640]

are you sure there aren't 3 wires in that part of the loom, try stripping it back a bit and where you are saying shouldn't have a ring terminal, it should be a plug

[vectra640]

as you look at the car the loom exits the interior on the left side then runs to the engine to the injector plugs on the black cover right? How far back from the injectors on the loom does this wire appear from roughly

take a pic of the entire loom on the engine to give us an idea of where it is, does it have a brown RON plug with a LAMBDA plug on the same part of the loom?

[cooper_mark]

it comes out between the first and second injector plug

[vectra640]

Air temp sensor, is it definitely an XE loom? there are no extra plugs on it are there?

[vectra640]

Right, one is the intake temp sensor and the other is the TPS and there should be a single black wire with a ring terminal on it

[vectra640]

If you have the Temp sensor plug and the TPS plug then twist the brown and black wires together and ground them both on the fuel rail

[cooper_mark]

this is where mine wast bolted the ring terminal came off so i stripped it back to find that it was a double core wire
yes it is black(outer casing but the inner wire is brown/gray trace

[Andy K]

I didn't think the M2.5 had an air temp sensor.

It wouldn't surprise me if that pic was an earth.

[cooper_mark]

If you have the Temp sensor plug and the TPS plug then twist the brown and black wires together and ground them both on the fuel rail

think u've just answered my question
basically all i wanted to know is do join the 2 together then earth it or do i only use the brown/gray and earth that

[cooper_mark]

Temp sensor plug .....??? where's this

[vectra640]

air intake temp sensor should come out the same place as the TPS plug but will only be a 2 wire plug whereas the TPS has a 3 wire plug on it and then a black sheathed earth cable with them both the other end has 2 earth ring terminals iirc