I bought a used Mazda 3 year 12/2005 from Italy. This car has a diesel engine 1.6 Turbo same as Ford/PSA. I have a loose three pin cable that don't know where does it belong. I've checked with 2 different mechanics but they don't know either. Can someone help me to find the function of this cable? It ends up at fuse box but cant find where exactly because its wrapped with some other cables.enter image description here

  • top-right -- battery cover
  • bottom-left -- engine cover
  • bottom-right-- fuse box [not present on the picture]
  • anything under the cover top right?
    – Solar Mike
    Jul 20, 2018 at 7:19
  • the cover top right is the battery, but this cable goes under that box, is attached to some another cables (at the angle) at the bottom and then enters the fuse box, not present in the picture, but a little more at right
    – emirjonb
    Jul 20, 2018 at 7:30
  • 1
    and cover bottom left? By the way, add the info to the original question.
    – Solar Mike
    Jul 20, 2018 at 7:33

3 Answers 3


This cable may belong nowhere because it's meant for a feature that your car doesn't have. Wiring looms come pre-assembled, typically manufacturers make one that works for all or most models of a vehicle rather than having one custom to a specific set of features, so it's not unusual to find a cable that doesn't do anything. Of course it could be something important, so you're right to trace it.

I'd suggest testing the pins with a multimeter to see if they have power, if not you can look at which fuse slots are not filled. If it does have power then you can try pulling fuses until the power drops, then you know what it's for. Wires with alligator clips on each end are great for this kind of work, you clip one end to one of the multimeter ends and the other to one of the pins on the connector, saves you having to fiddle around each time.

  • Thank you for your hints, but I don't have a multi-meter to test it unfortunately, I was hoping for someone with a similar car to check under the hood if they have something similar detached or attached somewhere.
    – emirjonb
    Jul 20, 2018 at 9:32
  • You might get an answer here, although you'll probably be better off on a Mazda forum specifically @emirjonb
    – GdD
    Jul 20, 2018 at 12:05
  • I've already registered on two forums but they seem old not well organised
    – emirjonb
    Jul 20, 2018 at 12:25
  • One approach you could take would be to make some educated guesses what it could be using your fuse diagram and then search for replacement parts. Also find what optional extras there were and compare to what features your car actually has. Of course, if everything seems to work you could just not worry about it.
    – GdD
    Jul 20, 2018 at 12:28
  • Yes I've tried to find it but it's a little hard for this model, I can't reach to the rail sensor to check it. Have to try to unscrew the battery and take a look
    – emirjonb
    Jul 21, 2018 at 17:25

Is the car giving any engine codes? That looks like a sensor connector (ECT, maybe?) - but if an engine sensor is left unconnected, it's usually going to give an error code.

  • In fact it's giving an intermittent low fuel pressure but it's not listed as permanent error code. does the unconnected sensor give this kind of error?
    – emirjonb
    Jul 21, 2018 at 15:49
  • It's an excellent clue. Going from that error message (probably P0191), and from the end of the cable in your image, I'd start looking for the Fuel Rail Pressure Sensor. In your image, it's on the right side of the engine, underneath the cover that your hand is on. Shouldn't take more than a few minutes to check.
    – PeteCon
    Jul 21, 2018 at 16:11

As others have said it probably leads to nothing if there are no error codes. Do you have a multimeter? if so do a continuity check to these wires and the fuse box until you get a hit. Then you will know exactly what it is.

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