Cosworth Conversion

Engine Wiring loom

Mounting the ECU

In the Granada the ECU is mounted behind the glovebox and so the engine wiring loom is laid out to reflect this. Therefore, when transferring everything into the Cortina, the ECU will need to be mounted in a similar position. How you mount the ECU is up to your discretion. The reason I say that is because I haven't got around to mounting mine properly yet! However, this is trivial compared to the task of installing the loom!
The first headache is getting the loom routed from the ECU within the cabin through the bulkhead/engine firewall and into the engine bay. There's only one way to do this, make a blumin big hole that the biggest connector on the engine side will pass through. To seal the excess of the hole afterwards I wrapped a strip of rubber around the section of loom that passes through the hole and secured it with a band of insulation tape. It was then secured in place with black silicone sealant.

The Connections

This isn't quite as hard as you might first imagine but there are a few pitfalls to watch out for. All the main sensor connections are easy and pretty much self explanatory as they each have a different shaped connector so if you could match shapes at play school you can do this bit!

The Missing Links!

This is the fun bit and the part that took a fair bit of pouring over incomplete wiring diagrams and back probing of the engine loom with a multi meter.

The missing links are:

                                        1. Ignition switch signal to turn it all on
                                        2. Rev counter output
                                        3. Fuel pump relay feed and switched earth
                                        4. Temp sender output

The first bit to wire in is the ignition switch on wire. It is hiding in a section of the loom that naturaly runs across the front of the bulkhead panel under the heater box and has a white plug on the end as shown below.

There are two wires attached to this plug, one black and one green. The black wire is the switch on wire and needs to be connected to the 'ignition on' side of the Cortina's wiring loom.


The easiest way to achieve this is to wire it directly onto the corrosponding post on the vehicles ignition barrel switch.


The other wire from the white plug coloured green is the signal for the rev counter. This can either be connected straight to the instrument cluster multi plug or is can be connected to the green wire on the vehicles own loom that would have attached to the ignition coil.
The original rev counter won't work however as the new engines ecu will be sending it the wrong type of signal. You will need to make a hybrid rev counter by installing the internals from the Granada's rev counter into the Cortina's instrument cluster. To see how this is done take a look at the link below:

Rev Counter


The fuel pump feed and switched earth connections need to be attached to the two wires you installed earlier when you fitted the electric fuel pump. These are hiding in an oval 6 pin multiplug that can be found in a part of the loom near the ECU that would have originaly run under the Granada's dashboard.

The middle two pins are the ones you require for the fuel pump.


That leaves the temp sender output connection. This isn't part of the engine loom, all you do is connect the relevant cable from the vehicles own loom straight onto the temp sender mounted underneath the thermostat housing.

The rest of the various plugs left over are not required and can be left. Be carefull if you decide to snip them from the loom to 'tidy it up' as there are some connections assoiciated with the fault diagnosis system and the fault code reader.


I've lots more electrical info to put on here including some user friendly wiring diagrams and as soon as I can find what I've done with them (or make some new ones) I'll post them up. Until then, if you have any questions then please feel free to send me an EMAIL.

Good Luck!