Mk1 Wiring Clarification

[bytesandbolts]

If anyones able to confirm my reading on what the wires do below that would be great.


I believe this is just a ground wire, however I'm not sure what the plastic mounting pieces purpose is for though?


Pretty sure this is the wires used for hooking up a radio (so is just switched ignition).

[davemk1]

The wire in top pic is as you say a switched accessory/radio wire.
bottom pic.
look in the part of the loom where that black wire comes from and see if there's another one which has a male bullet connector on the end.
on my car these two black wires go to a white wire which is looped around the back of the rev counter.
pic attached.

[davemk1]

Oops. I got your pics the other way round!

[davemk1]

The brown and white wire is connected the same on mine too. Not a clue what is does though!

[bytesandbolts]

Yeah I think the brown is just a ground, but don't know why Ford decided to use that plastic riveted thing.

[Tony B.]

Bytes, in your first pic, I am fairly sure that "plastic bit" should be the resistor for the slow speed of the two speed heater motor. It does go to earth but after passing through the resistor. There should be more to it, on mine there is a wound coil mounted on a metal plate.

In your second picture, the grey / yellow wires do look like wires that are live when the key is in the "Acc" position, to confirm, is the wire feeding them in the black part of the plug yellow ?.

[bytesandbolts]

Bytes, in your first pic, I am fairly sure that "plastic bit" should be the resistor for the slow speed of the two speed heater motor. It does go to earth but after passing through the resistor. There should be more to it, on mine there is a wound coil mounted on a metal plate.

Okay that makes more sense as the plastic bit actually has a purpose then. The 2 speed motor works fine and that portion of the wiring harness is still stock AFAIK. It's a late 74' escort so perhaps Ford changed how they do the resistor. Perhaps post a pic for comparison if you can.

[Miniliteman]

Ford uses brown as a ground-wire.
Brown with a tracer (in this case) white will never be a ground-wire.

[bytesandbolts]

After some digging I can confirm the brown wire w/ white trace is the low speed return wire for the heater blower, the plastic housing at the ground point is a resistor to reduce motor speed.

Detailed in the diagram below.