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Mini Mpi Ecu Problem


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#16 bigmotherwhale

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Posted 09 November 2007 - 02:25 PM

im thinking the same simon ive got a feeling they will plug in the diagnostics and the ecu will not work at all or something like that. pming sprocket was the first thing i did lol, he seems to know his mini wiring quite well!

#17 Sprocket

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Posted 11 November 2007 - 07:41 PM

Yes, the ECU only grounds the relay coils.

To check this in a true situation, first remove the two 36 way connectors of the ECU, one red one black. With a DVM check for voltage on the white pink wire at the ECU connector. There should be 12 volts. if there is not,the main fuse link in the engine bay has blown or the relay pack is faulty. If there is 12v, use a piece of wire with the ends stripped back and connect this pin to ground, the Main relay should now be energised, if it does not, the relay pack is faulty. If the relay energises, onto the next step.

With the main relay still energised, check for voltage on the black/ green wire at the ECU connector, if there is no voltage there the relay pack is faulty, again with a piece of wire connect this pin to ground, the relay should energise the O2 sensor heater relay, if it does not, the relay pack is faulty. There is no need to keep this relay energised for further tests

With the ignition switch on ( lights on on the dash) check for 12v on the black/ purple wire, at the ECU connector, if there is no voltage, fuse A4 in the passenger compartment fusebox has blown. If there is voltage, again using a piece of wire with stripped back wires, connect the pin to ground, this time only momentaraly, the relay should energise and the fuel pump should run. If the relay does not energise, the relay pack is faulty, if the relay energises, but the fuel pump does not run, fuse C7 in the passenger compartment fusebox has blown, or the inertia cut off switch is open circuit, or more commonly these days there is a wiring fault on fuel pump power circuit, or worst case, the fuel pump is faulty.

Do not leave the fuel pump relay energised, it is not needed for further tests

Last relay to check the starter relay is a little more complicated in the sense that it is controlled via the imobiliser/ alarm ECU. The easiest way to check this is to disconnect the alarm ECU and with a piece of wire connect the red white wire on the alarm ECU connector to ground, then turn the key switch to start, the engine should start turning over.

If after carrying out these tests, and no faults in the above have been found, the Alarm/ Imobiliser ECU or Engine ECU is FUBAR'd and will require specialist equipment to determine the real fault.

Try these people if it comes to that http://www.atpelectronics.co.uk/

#18 bigmotherwhale

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Posted 16 November 2007 - 07:00 PM

got this sorted now was a simple relay problem after all.

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