engine and drivetrain What Exactly Is In This Harness?

[mikebontoft]

In the process of trimming down the engine bay, this harness fell off. I think a couple went to temp sensors and the ignition coil, but what else is on this one? What's the relay box for? I don't have any emissions equipment left on it.

Guess I should find a PC to look at the service manual diagrams... just wondering if it's nothing I really need. I can make a new harness that's a lot cleaner.

[esty]

that's just more of the smog stuff...if you are de-smog'd you don't need it

[mikebontoft]

well in that case I think I'll make it so it's just the ignition stuff then. thanks.

[Mike Self]

When things electrical and electronic became part of the 2002 emission equipment during 1972 or so, the factory made separate wiring harnesses for all the emission stuff that went on US spec cars.  That way they could use the same basic whole car wiring harness set for both US and Euro spec cars; the US emission stuff would all be add-on.  Easier to manufacture and also easier for us to remove lo those many years later.

 

mike

[FunkyLaneO]

If it is a '74 or newer, there is a useful resistor wire in there.  If you have not switched to a blue coil you may want to remove that wire from the bundle and use it to energize your coil. It is the bulky wire with clear insulation. At the very least it may be valuable to somebody else so don't throw it away.

[mikebontoft]

Yeah it's a '75... still using a red coil.

So there's absolutely nothing else I need in it then? Just the power to the coil, and...

[FunkyLaneO]

Nothing else, the red coil I believe does not require a resistor so you can replace that entire bundle with a single wire from the fuse box (switched power, fuse 11 I think, whichever one you unplugged it from) to the positive terminal on the coil.

 

If you were using one of the wires for an electric choke you will need to run a wire for that too as well as the fuel shutoff solenoid if you have one (can use the same wire as the choke if you have both).

Edited December 2, 2013 by FunkyLaneO

['76mintgrün'02]

the red coil I believe does not require a resistor

 

you might double check this.

I thought red and black did, but blue did not.

 

I searched and found this:

http://www.bmw2002faq.com/_/technical-articles/electrical-and-ignition/ignition-coil-myths-busted-r52

[mikebontoft]

dual dcoe's so no choke for me!

 

Unfortunately the red coil does need a resistor... I learned that the hard way (blew up my igniter).

 

Well that's pretty cool then. Thanks guys.

dual dcoe's so no choke for me!

 

Unfortunately the red coil does need a resistor... I learned that the hard way (blew up my igniter).

 

Well that's pretty cool then. Thanks guys.

[FunkyLaneO]

Sorry, brain hiccup, you are correct red coil does require a resistor. Not sure why I was thinking that it didn't.  Old age I guess.

[JohnS]

With the red coil you should use a 1.8 ohm resistor.  The resistor wire on the later non-tii cars is only 0.9 ohms.  Better to bypass that resistor wire and use the correct 1.8 ohm external resistor.