Focus ECO switch help

[jessebaker09]

I'm thinking of installing an engine off coasting switch for my 2005 ford focus. I would like the switch to turn off the injectors and coil without setting off any trouble lights (so that I could bump or key start the car again with no problems). Just the injectors being shut off would be ok. I was wondering if tapping a fuse with a switch and another fuse in series would be possible or if there would be another solution. Thanks.

Also I don't have a wiring diagram for the injectors or the fuse box, if anyone has them or knows where I could get them that would be awesome.

I love learning things from this site, this is my first post.

[AndrzejM]

Hi,
Cutting current to injectors can throw trouble codes - unfortunately. The best is to cut signal from crank position sensor, or cam position sensor. Depends on the car. It "tells" ECU that engine has stopped so ECU is cutting off the fuel and sparks.

It's best to find a wiring diagram for your car and then find the right place to cut the signal.

[jessebaker09]

That is a bummer. Do you know if the Haynes manuals have wiring diagrams or is there a better source somewhere for those. Where do others get wiring diagrams? I have also heard of people making an injector switch activate a dummy resistor circuit to trick the ECU but idk if that would work on my car.

In any case, would a simple switch work for those sensors or would I need a relay as well?

[AndrzejM]

Hi again,

I've found some information regarding Focus ECU wiring.


As you can see pins 30 and 55 are responsible for cam and crank position sensors. But you have different engine so probably your ECU and wiring will be different.

Anyway you can look for the sensors and try to disconnect them for a few times and you'll see if ECU will throw any errors.

Then you can thing of permanent solution.

It's better to put rely close to the sensor, because that's a sensor and any noise from long cables can cause trouble with the engine.

Good luck!

[jessebaker09]

Ok, guess I will order my materials then. In the mean time I will look for a layout like that for my engine. I'm crossing my fingers that this will work. I saw some troubling EOC threads that may mean I have to recycle the key anyway to restart my car. In any case it will be a good project. Thank you for the Help! I will post detailed results and method once the project is complete.

[AndrzejM]

Originally Posted by jessebaker09

I will post detailed results and method once the project is complete.

I'm counting on that!

Good luck and keep us posted

[jessebaker09]

I got my parts in the mail! I found a great deal on some momentary switches on amazon. Those haven't come yet so I will use these toggle switches until they arrive.

[jessebaker09]

I don't think the pictures of my parts came through, I will try and attach them again in this post.

After I got my parts I purchased a digital service manual for 03-07 ford focus on ebay for 10 bucks! It had all the wiring diagrams I needed (so I thought). I found a diagram of the inputs to the powertrain control module (PCM). This showed where the location of the PCM under the glove box. When I looked got to the PCM I found the plug-ins did not have numbers to mark the wire locations, DANG! There were too many wires here for me to feel comfortable to go off color.

Next up was to get to the Camshaft Sensor wire on the engine compartment side. So I took the Battery Box out to get to the main harness. After getting to it I was frustrated to find there was no brown wire which was the one I was looking for! At least I have clean battery terminals now

[jessebaker09]

After looking more at my service manual I located the camshaft sensor! At this point I decided not to act before asking which of the two wires to cut and put the relay to? The White/Violet wire goes to the computer sensor. The Brown/White wire goes to the Signal Return. Now it seems to me it doesn't matter which side I cut, but I think I am also just a little scared I will break my car. Please reassure me I won't. I'm not asking for a warranty but I'm just not sure what even could go wrong. Anyway, thank you. I attached location pictures in case anyone wants to find this on their 05 focus.

[AndrzejM]

Hi,

Have you tried to disconnect that sensor while engine is running? That should be your first step. If that will work and after connecting sensor you can start your engine without ECU throwing an error then you can go to the next stage.