1975 124 Spider 8 Relays?

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kendall
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1975 124 Spider 8 Relays?

Post by kendall » Sun Jul 21, 2019 7:52 pm

Hello Everyone,

I was doing some work today, replacing fuses and headlights, and discovered that I have 8 relays, 2 by 4, on the driver side fender. I'm really confused as all the literature I see states that there should be 6 relays total. It doesn't help that it seems like half the wires have been cut and duct-taped back together, but what can I do.

Does anyone have any info about a 1975 124 having 8 relays? Or is this something a PO did? I hope I don't have to trace them all, but if that's the case, what can I do.

Also, regarding the fuses, I don't have the cover on my fuse box. The factory manual states that position A is a 25 amp fuse and the rest are 8 amps. Fuse A is on the left side?

Thank you all very much. I appreciate having this forum to get quick feed back on problems I'm encountering.
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bartigue
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Re: 1975 124 Spider 8 Relays?

Post by bartigue » Sun Jul 21, 2019 9:17 pm

This document describes the relays:
https://www.mirafiori.com/forum/downloa ... php?id=331

Fuse box is mounted upside down.
-----------------------------------------------------------
Brad Artigue
1969, 1969, 1970, 1979, 1980, 1981, 1982, and 1982 124 Spiders
1969, 1970 850 Spiders
77 X1/9
http://fiat.artigue.com
kendall
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Re: 1975 124 Spider 8 Relays?

Post by kendall » Sun Jul 21, 2019 9:45 pm

Hi Brad,

Thank you for the reply. The diagrams in that document make everything much clearer.

I don't understand what you mean by the fuse box being mounted upside down.

Is fuse A on the right? Are there markings on the fuse box itself that identify the positions?

It looks like the PO hard wired the radiator fan to always be on. I assume the relay/fan switch are bad. Is there an easy way to test the fan switch? Does changing the fan switch require draining the coolant?
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bartigue
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Re: 1975 124 Spider 8 Relays?

Post by bartigue » Mon Jul 22, 2019 7:42 am

Fuse A is nearest the steering column, yes, to the right. L, I, H, G, F, E, D, C, B, A. There is no "J" for reasons I don't know.

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The fan units are extremely reliable and the connections are simple – which makes it a mystery as to why so many cars have experienced so much abuse in the fan connection arena.

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The fan always receives unswitched+12V (a light blue lead on the 1981 example above). The ground wire for the fan runs to a temperature sensor mounted in the radiator bottom, then from the temperature sensor to the fender grounding post. When the radiator temperature hits around 200 degrees F the switch closes, grounding the fan and turning on the fan. The switch opens again around 190 degrees, turning off the fan. For practical purposes this means your fan should kick on when the needle on your gauge hits around the “0” in “190” and turn off when it is back on the “9.”

Fan problems are almost always attributed the switch or leads. In reality most fan problems are phantoms; the instrumentation reading “hot” when the motor is not.

Most cars I've owned have some fan hack done to them. I un-do the hack and return it to the factory wiring. Then I diagnose the cooling system. If the lower radiator is getting hot and the fan switch isn't grounding then the switch is bad. Most of the time I find the problem is the thermostat isn't opening or the system simply hasn't been bled of air completely.
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Brad Artigue
1969, 1969, 1970, 1979, 1980, 1981, 1982, and 1982 124 Spiders
1969, 1970 850 Spiders
77 X1/9
http://fiat.artigue.com
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Re: 1975 124 Spider 8 Relays?

Post by kendall » Tue Jul 23, 2019 12:17 am

Thank you for the diagrams.

Just so I understand, the fan is seeing power through the fan relay? In that situation what is the purpose of the fan relay if the radiator mounted switch is controlling when it turns on? Isn't a relay supposed to be a switch for a greater powered device, more or less?

Or does the fan get power directly from the fuse box?
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zonker
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Re: 1975 124 Spider 8 Relays?

Post by zonker » Tue Jul 23, 2019 1:56 am

The fan relay's purpose is to off load the higher amerage needed to operate the fan, which saves the thermo-switches and ignition switch from burning
up prematurely, or developing a problem because of a poor ground. Different model years are wired differently, and I'm not sure of your '75, but the pre '74 models get their main power from an unswitched source (fuse A to terminal 30 on the relay), the temperature switched power load comes from a switched 12V source on the fuse box, to terminal 86 on the relay. The radiator thermo-switch energizes the relay by grounding out terminal 85.

Personally, from a product design standpoint, I find the mounting point of the cooling fan switch in the bottom of the radiator (it's coolest point) a poor choice. It seems to me the better designed systems have the thermo-switch mounted in the water outlet or in the cylinder head. What I've done to my '71 is to source a 175 degree single terminal cooling fan switch from a Honda motorcycle and mount it on the intake manifold water passage, in a threaded hole under the carburetor. I run an additional wire to the radiator mounted switch on the relay side, so now I have two switches, one that will activate the cooling fan if the water under the intake manifold reaches 175 deg F, or the stock switch that can activate if the bottom of the radiator reaches 185 degrees. Also I now have double insurance the fan will now work in the event one of the cooling fan switches fails or loses good ground.
1969 1971 1971 1981 2017 124 Spider
2013 500e
1974 1978 X1/9
spider2081
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Re: 1975 124 Spider 8 Relays?

Post by spider2081 » Tue Jul 23, 2019 7:35 am

I have seen a number of spiders with the fuse panels mounted upside down. So now I look for the wire colors from the wire diagram on the end fuses to identify fuse #1
A point not mentioned: If a Spider has a factory installed coolant fan relay the fan can only run if the ignition switch is in the "on or run" position. Spiders without the relay the fan can run with the ignition key removed from the car.
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friedman
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Re: 1975 124 Spider 8 Relays?

Post by friedman » Tue Jul 23, 2019 8:39 am

I have a 75 spider project and if you are really motivated you can remove at least four of those relays as they have to do with emissions equipment.
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bartigue
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Re: 1975 124 Spider 8 Relays?

Post by bartigue » Tue Jul 23, 2019 2:20 pm

spider2081 wrote:
Tue Jul 23, 2019 7:35 am
I have seen a number of spiders with the fuse panels mounted upside down. So now I look for the wire colors from the wire diagram on the end fuses to identify fuse #1
A point not mentioned: If a Spider has a factory installed coolant fan relay the fan can only run if the ignition switch is in the "on or run" position. Spiders without the relay the fan can run with the ignition key removed from the car.
I'm fairly certain they were all always mounted upside down. FIAT could re-use a part better than anyone as on other cars of the 60s and 70s that thing is mounted sideways, right way up, upside down, but never backwards. That would be electrifying.
-----------------------------------------------------------
Brad Artigue
1969, 1969, 1970, 1979, 1980, 1981, 1982, and 1982 124 Spiders
1969, 1970 850 Spiders
77 X1/9
http://fiat.artigue.com
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zonker
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Re: 1975 124 Spider 8 Relays?

Post by zonker » Tue Jul 23, 2019 4:51 pm

bartigue wrote:
Tue Jul 23, 2019 2:20 pm
I have seen a number of spiders with the fuse panels mounted upside down. FIAT could re-use a part better than anyone as on other cars of the 60s and 70s that thing is mounted sideways, right way up, upside down, but never backwards. That would be electrifying.
Haha shocking indeed. The fuse panels do have the letters embossed into them so if it is upside down, you can always get a magnifying glass and read the letters on the plastic.

As for converting to run when key is off, that can be done with the relay setup as well, it just means moving the current source to a battery only place. I mount a 5/16" insulated stud inside the passenger compartment and feed it with an 8 gauge wire from the large terminal on the alternator. I use this to run any add on equipment like electric fuel pump, stereos, subwoofer amplifiers, as well as a "brown wire mod" to help offload the old original wiring. The original wiring becomes the switched signals for the added relays such as the fuel pump, radiator fan, horn, headlights, etc. It cures 90 percent of the electrical gremlins that occurs on these little Italian gems.
1969 1971 1971 1981 2017 124 Spider
2013 500e
1974 1978 X1/9
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