Tuesday, March 19, 2013

Fuel pump and alternator charge warning light

If there's anything I've learned by undertaking this build, it's that small steps add up and help you gradually overcome what seems like an insurmountable to-do list at first glance. Following that philosophy, tonight I crossed off two items from the list; one was the alternator charge wiring.

Upon very brief study of the EA factory workshop manual schematic, it was apparent that one of the two "indicator" wires needed to be joined to the main power feed coming from the alternator, and the other needed to be a trigger for the warning light (it's ground when the alternator is not charging, and +12v when it is, which means the light on the dash is illuminated at any time the dash is supplied with 12v from the ignition but not with 12v from the alternator. Thankfully, I'd planned (although possibly forgotten) for this and previously ensured the dash was wired to function the same way - my handwritten wiring diagrams quickly showed me what colour wire I needed to connect to under the dash and stated that this wire was a -ve trigger for the warning lamp.

It certainly helps to make things easier for yourself when undertaking a big wiring job and this was no exception, not only did I have the colour and function of the wire listed, but when I looked under the dash I'd had the foresight to tape and label the relevant wire with a peice of masking tape. It's the little things that you do while they are obvious that make jobs like this soo much easier to come back to!

Extending the alternator charge lamp trigger wire.

The next job was actually relevant to moving forward my progression to a test-running of the engine. I wired in the fuel pump.

Unfortunately, Ford in their infinite wisdom neglected to include the pin configuration for the fuel pump in the wiring schematics (despite including what would appear to be accurate pin outs for the entire remainder of the vehicle). This connection is a standard 2-way connector as also used in falcons on the door speakers and indicator lamps; as well as on many other vehicles. Unfortunately, Ford don't seem to have a consistent manner of using the connectors - on one of the two examples listed above, the top pin is ground, and on the other, the bottom. Ford's diagram only list wiring colours but these don't match the wires at the pump and I can't find that part of the Falcon loom (it's possible we never retrieved it from the donor car).

As a result, I've taken a punt that the red wire coming from the pump will be positive and the white wire (again from the pump to the 2-way connector) is the ground - the Ford diagram shows that power runs to the pump from the pump relay and then to ground. I've grounded the pump in the boot area and run the wire back to the rest of the relays in the passenger footwell through the metal tabs provided by BMW for wiring down the passenger side of the vehicle.

I made a slight change to the Fuel Pump relay (pictured above as bottom left-most relay) in that while it is still fed a positive signal when switched, it does not have a constant ground. The ground is now triggered by the ECU which allows the ECU to turn the fuel pump on and off per the factory configuration when the motor is switched off. The manual toggle switch will still allow me to cut fuel with the engine running in case I need to relieve pressure to work on the fuel system, and I will be leaving a permanently grounded female spade connector next to this relay so it can be changed over for priming the system etc.

Finally, a picture of the ECU mounted. I think I've already taken a photo of this, but I worked out if I hold the LED stick light next to the iPhone when I use it for these interior photos, the lighting and hence definition is a little better. You can see my masking tape labels in full effect here :)

More progress to come through the next week!

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