Sale ends todayGet 30% off any course (excluding packages)

Ends in --- --- ---

Sierra Cosworth wiring - build

EFI Wiring Fundamentals

Forum Posts



Tech Articles

Discussion and questions related to the course Motorsport Wiring Fundamentals

= Resolved threads


Hi All,

I started today on getting the wiring sorted for the Forsd Sierra Coworth I am in the process of building and thought I would share a bit of a build thread as I go. I realise there is a build thread forum but thought I would keep this thread focused on the wiring - admins let me know if it needs to move.

To say I started today would be a bit of an understatement - I have spent the last couple of months traking down hardware, researching and learning as much as possible. This is my first go at wiring a car so I am hoping to implement what I have learned here and elsewhere. After all this prep work, today I started getting some of the physical work started which was a relief.

A bit of background - I am building a 1997 Ford Sierra Cosworth (3dr) to amongst other things race in Improved Production Racing in Australia. I purchased a bare shell at the beginning of the year and will be fitting a YB Cosworth Turbo engine to it that I hav in the garage.

On the electrics side, from the elctronics point of view I am running the following:

Motec M880 ecu

Motec CDL3 dash/logger

Motec DBW4

Dual Motec PDM15's - 1 for the front and 1 for the rear of the car.

I also need to wire up all the ancillaries in the car - headlights, indicators etc.

I have chosen to go the Tefzel route for all the wiring, Autosport connectors (ECU, DBW4 and firewall), DTM connectors where possible and what ever connector is required for each sensor. As well as that, I have had to track down OEM connectors for things linke taillights etc which was not easy for a 30yr old british car especially when you are in Australia but I have managed to get all the required connectors so I can product an entire new loom withouth having to use pigtails from an old chassis loom.

There are 29 sensors to go in as follows:

Wheel speed x4

Crank / Ref

Manifold Air temp, Inlet air temp, Manifold Pressure (MAP)

Fuel pressure, Fuel temp

Oil pressure, Oil Temp

Throttle position Driver, Throttle Position engine

Brake Pressure Front, Brake Pressure Rear, Clutch pressure.

Gearbox Oil Temp, Diff Oil Temp, Engine Temp, Exhaust Temp, LAMBDA

Steering Angle, Turbo Speed

Brake Temp x4

As well as 4x injectors, 4 x coils, boost control

All powered devices will be managed via the PDM's which will also be responsible for logic operations like turning on / off cooler pumps at set temps etc. All the motec devices will communicate over CAN with the CDL3 arbitrating between the M880 and the PDM's.

I have spent the last couple of weeks buying bags and bags of connectors pins, wire etc and finally today got to getting a dummy fit done. First off was to get the hardware mounted in the car and then I got to work running test runs using cotton rope - a) to figure out what all the paths are, b) to get an idea of lengths for all the required runs and c) to perform a sanity check and make sure I have covered everything. Many hours have been spent on the spreadhseet but I find it is much easier to take it all in once you can see it all in the car and visualise where each component is in the car.

I got about 2/3rd of the way through the dummy runs today and will likely get it finished next weekend After which I should be in a position to start cutting wire and laying out the loom.

A couple of pics of todays work:

For those who are interested, here is the worksheet I am working off -


It started off a bit scattered but has got a bit more oranised as the work progressed.

I will post more updates over the coming weeks as it comes together.

Sweet choice of car, mate - I'd suggest leaving an extra bit of slack in the runs to controls, etc, unless you have already verified you can reach them all when seated in the position you will be using, remembering you will be strapped down and unable to stretch properly.

Most connectors use common terminals, so if you find you're stuck you can use one of the commonly available tools to remove the old terminal and fit your new, wired, terminals. The trick, of course, is finding acceptable terminal blocks to use.

Cheers Gord, Sorry, forgot to add, there is also a Motec CAN 15 keypad going in. It will be setup well within reaching distance when seated and belted and only requires CAN and power. It will be controlling everthing that isnt automated.

Looking forward to see the development of this beauty.

Motec M880 my favorite ECU.

Art desk at least.


Ben, sounds like a pretty epic build! Can't wait to see it progress! I can't see your pictures though? Might be a google permissions/sharing issue?

Yeah, it is getting harder and harder to share images these days. Here they are again, this time uploaded onto a private server.

Oooooh yes, that looks well legit :-). I almost like seeing the planning photos more than the finished article photos! Looking good :-).

Talk about jumping in the deep end... Most peoples first wiring job would be something like a cortina with a carb and distributor!

How come the DBW4? Normally that would only be used for engines with dual TB's, or were you running short on IO?

Yes Adam, I ran out of I/O on the M880 and it was a toss up between a DBW4 and E816, if I went the E816 I could have left DBW control on the M880 and moved some sensors to the E816 or I could go a DBW4 which would provide dedicated control of the ETB and TPS whilst freeing up a couple of AUX slots on the M880 - in the end I managed to get a DBW-4 for a much better price than I could have got the E816 for so went that way.

And yes, I do like jumping in the deep end :) This build will be a number of first's for me - first time I have built a cage, first time I have wired a car... Is the best way to learn :)

We usually reply within 12hrs (often sooner)

Need Help?

Need help choosing a course?

Experiencing website difficulties?

Or need to contact us for any other reason?