Download ECU and injection wiring for Pinto (Sierra EFI)

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ECU and injection wiring for Pinto (Sierra EFI)
This is a basic description on how I have gathered that the wiring can be done when
retrofitting a Sierra EEC-IV electronic injection/engine management system into an older car.
In my case I fitted the system from a 1988 Sierra, with catalytic converter, into a 1974 Capri.
There are some differences between this version of EEC-IV and the more common “noncatalytic” version, the biggest wiring wise is that the non-cat version does not have the 12v
live feed to pin number 1. As far as I know that is the only difference that matters here.
This description also relies on that you have a rather complete Sierra enginebay loom from the
donor of the ECU, ie matching the ECU and components. The main relay wiring is however
not reused, but altered according to the description below. This is just because that is what
suited my application best.
To understand the wiring concept, it helps to have a basic understanding of how the EEC-IV
powers up when you turn the key.
When the ignition is switched on, +12v should be fed to the ignition coil, to the TFI module
(the ignition amplifier), the injectors, the fuel pump relay and to the ECU (to pins 37 and 57).
When the engine runs, the ECU pin 22 is earthed, which in turn powers up the fuel pump.
The power to the injectors and ECU pins 37 and 57 is fed via junction S-119, the feed wires
are black and the junction is pretty easy to find when the loom is stripped. The feed to S-119
should come via the C-1936 connector, that is fed by a red wire from the main relay pin 87.
The C-1936 connector should be near the ECU/instrument cluster, on the passenger side in the
Sierra, and it is a 9-pin connector.
Normal care should be taken when wiring – always use adequate fuses, check and double
check all connections before powering up.
Note that the Sierra has a safety intertia switch between pin 87 of the fuel pump relay and the
pump – for added safety this switch can be used here too. But the ECU shuts down the pump
when the engine stops, so I feel the circuit is pretty safe anyway. I also have a manual switch
in the cabin, that interrupts the wire from the fuel pump relay pin 85 to pin 22 of the ECU,
plus a battery master switch.
Use good quality relays – I had a problem with the main relay releasing while cranking due to
the drop in voltage – took me some time to find that...
DISCLAIMER: I take no responsability for any damage or injury you may cause if you mess
up trying to follow this description. You have to be reasonably confident with car electrics,
and most important, use good common sense (preferably combined with a Sierra wiring
diagram and a diagram for the car you are putting the EFI in).
Compiled by Gustaf Ulander, September 2001. Mail me at [email protected] if you
have suggestions or perhaps would like to say “thanks”. The information can be reprinted or
republished as long as you refer to me as the source.
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Wiring diagram
+12V
ECU 1
(late
ECU’s)
TFI module
(black wire)
Ignition
switch
Coil
positive
Main relay
pin 86
Main relay
pin 30
Main relay
pin 87
Junction
S-119
Main relay
pin 85
Fuel pump
relay pin 86
Fuel pump
relay pin 85
Fuel pump
relay pin 30
Fuel pump
relay pin 87
ECU 22
Fuel pump
Earth (-)
DISCLAIMER: I take no responsability for any damage or injury you may cause if you mess
up trying to follow this description. You have to be reasonably confident with car electrics,
and most important, use good common sense (preferably combined with a Sierra wiring
diagram and a diagram for the car you are putting the EFI in).
Compiled by Gustaf Ulander, September 2001. Mail me at [email protected] if you
have suggestions or perhaps would like to say “thanks”. The information can be reprinted or
republished as long as you refer to me as the source.