Zetec Electrics

Zetec Electrickery

This is of course one of the more daunting aspects of a conversion and information is often hard to come by. The engines come with there own looms which plug into the main vehicle harness to cover all the ECU's requirements and any power feeds required (such as HEGO/Lambda sensor power supplies) and signal outputs (Rev counter signal, coolant temp sensor signal etc...). Depending on which vehicle your loom came from it could have either one large connector (Mondeo) or two smaller connectors.

One thing to note, if your donor was an automatic then you will find that you have a rev limit as without the gearbox feed it will think it is in neutral. There is likely a pin that can be shorted to earth to overcome this but as the ECUs are obviously configured differently I don't know if the maps might also be different to better suite the characteristics of the automatic transmission.

The following is all based around the loom that I used ('98 Mondeo 1.8 LX 'Silver-Top') but should be common to most. All required connections are made via the large black square 42 Pin vehicle loom connector with the exception of two separate power supplies, one for the PATS (Passive Anti Theft System) Transponder Ring and one for the admittedly optional fault diagnostic connector also known as the Data Link Connector (DLC).

ECU Pin-Out List

Often the starting point so I shall get it out of the way first.
Below is the complete pinout list for the ECU along with which pin it connects to on the vehicle loom plug as this is the main interface for the conversion. A blank entry means that pin is not in use.
The numbers in the description denote the corresponding pin on that items connector.

Vehicle Loom Connector

This is the real interface between the engine management system and the rest of the car.
This is the interconnection between the engine loom and the vehicles main loom, everything travels to and from this plug. However, not all of the 42 pins need connecting; the table below details each pins function and whether or not it is required.
The table below the photos explains each pin in detail. The fifth column headed 'Connection Details' list the minimum requirements in red and optional additional connections in blue.
As you have all the details here for you I would recommend wiring up the diagnostics port or DLC connector and the corresponding Clutch and Brake pedal switches to allow full functionality. The two switches can just be wired into simple push switches rather than fitting switches to the pedals themselves, though the clutch pedal switch is also supposed to induce a 4,000RPM limiter to prevent over-revving the engine during gear changes.

This is the location of the single 42 pin plug on the mk2 Mondeo.

This is the interface between the engine management and your car.

Don't go and hack the plug off, this photo was taken after the installation was complete. In fact it might be tidier to use the plug in your application.

Rear view showing the plug pin numbering (the reason why I included these two photos).

Vehicle Side Connections

You will need to make up a power supplies circuit and you will need to connect to the PATS transponder ring and the engine management light. There is also the optional data link connector and the brake & clutch pedal switches.

Fig.1 - Power Supplies Circuit
Make up this circuit and connect as identified.
There is one item missing. It needs a crash switch adding to the fuel pump circuit to cut power to the fuel pump in an accident.

PATS System Connections.
Really very simple BUT you must have the engine management fault light wired up or it will stay immobilised.

Hmm, I don't appear to have finished this diagram. Answers on a post card...

The contents of this website are purely a reflection of my own experiences and knowledge gained whilst working on my various projects. Anything you do based on what you have read here is done so entirely at your own risk.
Personally I wouldn't trust someone like me with a lawn mower! You have been warned! Flapper-bat!