Taking apart eng. comp electrics; what is what?

[eriknetherlands]

Hi there,
I am in the process of dismanteling my engine compartment. I'd like to label the parts coming from the car correctly. , but limited in knowledge:

See picture;

'C' is coil I know; converts 12V to something that will spark.

What about the ones labelled a/b/d ; how are they called and what do they do?

(My car is a may '73 eu version carbed automatic)

 

[HB Chris]

B is the ballast resistor for your black coil, it is 1.1 ohms and keeps your points from frying. The newer red coil requires a 1.8 ohm resistor.

D is a relay that in a US coupe would be to activate the A/C fan in front of the radiator but I don’t see A/C hoses and yours is connected to the ballast resistor. It may be functioning as a bypass relay which bypasses the resistor only when cranking the starter to provide a little extra spark. These were common in early 2002s but I have never seen one in an e9 so that is a bit strange. And if you were to install a newer permanent magnet starter you wouldn’t need it at all.

A is a head scratcher. May 73 is too early to have the temp controlled electric radiator fan used with A/C but it looks similar. Time to check the wiring diagrams for green/white and brown/white wires.

 

[sfdon]

Are there 2 brown/white wires at your temperature gauge sending unit by your thermostat? Follow the brown/white wires there. One goes to drivers box and one goes to “A”

 

[HB Chris]

Are there 2 brown/white wires at your temperature gauge sending unit by your thermostat? Follow the brown/white wires there. One goes to drivers box and one goes to “A”

I’m surprised a May ‘73 coupe would have that but maybe it does.

 

[eriknetherlands]

Wrt the 'D' , my car does have a fan in front of the radiator (pic1), a brown wire runs to the 'd' thingy, but only connects there to the body with the same screw that mounts 'd' to the body there. It also has a non connected female spade dangling there (pic 2) ...
starts to look like an after thought? Was the front fan perhaps added later to aid in cooling?

 

[eriknetherlands]

Are there 2 brown/white wires at your temperature gauge sending unit by your thermostat? Follow the brown/white wires there. One goes to drivers box and one goes to “A”

Yip, I think what you mean are these:
(Pic 1) it has two white+brown wires, one goes towards battery, turns to the left headlight, runs in front of the radiator to the right; its bundled up with tape, so hard to tell for sure where it ends.
The other dives into a harness bundle just behind the alternator.

The 'A' does have a date code on it, it reads 2 '73.

Attached a detail pic of 'A' with, what is left of, the switching diagram on it.

So it serves to switch on the front fan if a certain temp is reached?

 

[HB Chris]

Erik,

The relay controls the fan in front of your radiator, it is controlled by the black box ‘A’ and was found on 9/73 and later coupes. It activates the fan when water temp gets too high so it is a safeguard measure. Do you have A/C? Every A/C equipped coupe had the relay and fan if it had A/C but A was only added in 9/73. So perhaps non A/C coupes also have this after 9/73.

 

[eriknetherlands]

I’m surprised a May ‘73 coupe would have that but maybe it does.

My car has been restored before, it has new fenders for instance. Also electric stuff may have been added in a previous life....

No AC in the car (but I am considering it; I have zero components yet). Could it be that it had AC somewhere during its life? Wiring harnesses seems to be 95% oem, a few dangling wires in the engine compartment, but non in the interior.

Interior Console has zero evidence of ever being anything else then a automatic with ventilation only however.

 

[eriknetherlands]

Erik,

The relay controls the fan in front of your radiator, it is controlled by the black box ‘A’ and was found on 9/73 and later coupes. .....

So the fan in front of the radiator was a later add on?

 

[Cornishman]

My December 1973 build CSI does not have that electric fan, nor does it have A/C. It is RHD, U.K. spec.
My assumption looking at the pictures is that the fan is aftermarket.

 

[eriknetherlands]

I've looked at the tech books PDF that i purchased, it gives this image. It seems that item '12" in the drawing is the black box "D"; the aux fan switch.

My point here being: the title of that schematic is "Automatic / Air Contdition Extra fan" -> Could it be that the extra fan was OEM for automatic equipped cars, to add in the cooling of the extra heat load from the Automatic box?

My car does has perfect OEM mounting points for the aux fan (with 2 holes for M6 bolts on each side; 1st image in post #5) ; it seems unnecessary to weld that bracket in the factory on a car that would never use it.

editorial: just to cross link subjects, the aux fan switch is also discussed here:

Air Conditioning aux FAN connections

My question is about how this switch works, and how it is connected ? is it a sort of transistorized relay ? how is it connected ?

e9coupe.com

 

[sfdon]

“Automatic “ means it activates automatically.
that is a factory fan.

 

[HB Chris]

Don, it could be for non A/C automatics as well. The fan is a factory unit.

 

[sfdon]

Don, it could be for non A/C automatics as well. The fan is a factory unit.

Humility is a learned trait… often learned too late in life…

I have been wrong so many times in my life that I should put

“I believe “ before everything I write or say. It would make life so much easier!

With cars this old we can be considered Automobile Anthropologists!

we agree that’s a factory fan, and it appears that little box shouldn’t be there at all for that build date. If it still works- keep it!

Maybe if It was in a Csl city pack I would keep it just for its curiosity sakes.

 

[HB Chris]

Since 99% of all US coupes are A/C cars it is understandable that we have never seen an automatic without A/C that has this feature but it makes sense as the radiator has trans cooling lines in it.

 

[HB Chris]

The Parts Book shows that euro Model 73 CSA automatics received the fan, relay and module and A/C was not the reason.