Hall sensor

Gotta love that wiring . . .
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markintheair
Posts: 56
Joined: Fri Oct 12, 2012 7:44 am
Your car is a: Fiat 124 Spider 81 FI - Corsa Rosso
Location: The Netherlands

Hall sensor

Post by markintheair »

Hi all,

Me again! Nearing completion now of my full restoration. I hope to start her up next weem for the first time after two years of a full restoration.

I've got a couple of wires though that I just can't figure out where they go.

First is the hall sensor wire coming out of my distribution cap:

Image

Then this little guy:

Image

And finally:

Image

The final two are both in the injection wiring harness.

Looking at old pictures I can see they probably need to be around the ignition coil, but I can't figure it out anymore. Does anyone have advice?
Only the fool looks at a finger that points at the sky.
'81 FI Spider 2000
18Fiatsandcounting
Posts: 3798
Joined: Fri Mar 15, 2019 11:23 pm
Your car is a: 1969 and 1971 124 spiders
Location: San Francisco Bay Area

Re: Hall sensor

Post by 18Fiatsandcounting »

The white wire from the distributor (with the 2-wire plug) plugs into a socket in the base of the heat sink around the coil. Look for it and you will find it.

As for the other two wires, I'm not sure. I believe that there was a "blank" wire connector that was used for diagnostics at Fiat dealerships, so maybe that is one of them. I will be working on an '81 spider this weekend, so I'll take a look if you haven't figured it out by then. You may have to remind me.

Neither wire looks like the one to the oxygen sensor on the exhaust manifold.

If you get it running, you can probably figure out what is not working in terms of lights, wipers, other items.

-Bryan
spider2081
Patron 2024
Patron 2024
Posts: 3015
Joined: Fri Jan 27, 2006 11:45 pm
Your car is a: 1981 Spider 2000
Location: Wallingford,CT

Re: Hall sensor

Post by spider2081 »

I believe the wire in the last photo ( with the male/female terminals) connects to the coil's - (D) terminal along with the brown white wire for the tachometer signal. The tachometer wire connects to the male spade on the wire and then the female spade connects to the coil.
18Fiatsandcounting
Posts: 3798
Joined: Fri Mar 15, 2019 11:23 pm
Your car is a: 1969 and 1971 124 spiders
Location: San Francisco Bay Area

Re: Hall sensor

Post by 18Fiatsandcounting »

That sounds right. The last remaining connector, the female one with the black plastic housing, is quite likely the place where technicians would connect diagnostic equipment to the engine. My recollection is that wire is near the air filter housing.

-Bryan
markintheair
Posts: 56
Joined: Fri Oct 12, 2012 7:44 am
Your car is a: Fiat 124 Spider 81 FI - Corsa Rosso
Location: The Netherlands

Re: Hall sensor

Post by markintheair »

Thanks guys! They're all connected now, with the exception of the "diagnosis cable".

Now I'm really curious what kind of device can be connected to that cable... :D As you said Bryan, it floats around the air intake.
Only the fool looks at a finger that points at the sky.
'81 FI Spider 2000
18Fiatsandcounting
Posts: 3798
Joined: Fri Mar 15, 2019 11:23 pm
Your car is a: 1969 and 1971 124 spiders
Location: San Francisco Bay Area

Re: Hall sensor

Post by 18Fiatsandcounting »

markintheair wrote:Now I'm really curious what kind of device can be connected to that cable....
This wire is a bit of a mystery. I believe it connects to pin 22 on the Electronic Control Unit (ECU), and that appears to be a "Lambda Tester Connection" if you believe the Internet. Probably best to leave it alone, unless you know someone very familiar with the Bosch L-Jetronic system in which case you could ask them.

-Bryan
markintheair
Posts: 56
Joined: Fri Oct 12, 2012 7:44 am
Your car is a: Fiat 124 Spider 81 FI - Corsa Rosso
Location: The Netherlands

Re: Hall sensor

Post by markintheair »

Yeah I'm gonna go ahead and secure the wire so it doesn't interfere with any other stuff in the engine bay. Thanks again!
Only the fool looks at a finger that points at the sky.
'81 FI Spider 2000
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