Relay Size For Starter

[18Fiatsandcounting]

It's fairly common for cars to have a "neutral safety switch" or the like, and its function is to prevent the car from being started unless the transmission is in Neutral (manual transmissions) or in Park (automatic transmissions). Both my '93 Jaguar (automatic) and '69 Chevy pickup (manual) have these. None of my earlier Fiats (manual tranny) have had such a switch, but that doesn't mean that Fiat didn't put them in later model years or in the automatics.

Some Fiat model years also had a high idle circuit which would maintain a high idle (1500 rpm) when the transmission was in certain gears (3 and 4 if I recall), and the clutch was engaged. The purpose was to prevent the engine from going way lean when the throttle was completely closed but in gear and with clutch engaged. Apparently this led to high NOx emissions. So, in the simplistic thinking of the 1960s and 1970s, the solution was simply to keep the throttle slightly open during these conditions, and this required a switch on the clutch pedal to sense when it was engaged. That's the one Steiny is referring to, and his approach makes sense (but see below).

Only one downside: In my younger (i.e., stupider) days, I tried one time to see how fast my spider would move on level ground with just the starter motor (ignition disconnected). I even tried to get it into 2nd gear with the starter motor cranking away. Answer: about 2 or 3 MPH. This craziness required being able to turn on the starter while the car is in gear and with the clutch engaged, though. The car has since forgiven me, I think....

-Bryan

[aj81spider]

I checked my wiring diagrams for a 1980 and both sets (I have what looks like to be a Fiat wiring book and the Artigue wiring diagrams) show no relay. I'd check the car carefully, but I don't think you have one.

Here's the starter circuit from the first one.

[RRoller123]

Yeah, the 80 definitely does not have one, but we will have to take a close look at Tim's 83 when he comes down next time. May have been added?
C31 I have already eliminated (sort of) by removing the badly warped white plastic housing, cleaning and tightening the Fastons and reconnecting them directly, with a heat shrink outer. That should resolve that. I suppose I could have soldered all of them, but under the dash, a pita, this should be fine.



It is C6 and C7 (hard to read the diagram, but I think that is what those are) that need to be eliminated, replaced with solder. No reason for them that I can see, and they cause endless trouble. C12 isn't in my car, I suppose it isn't there unless power window option was installed.

[spider2081]

I think Fiat installed a relay between the ignition switch and the starter solenoid in all cars delivered with an automatic transmission. It prevented the engine from starting if the transmission was not in "Park" position.
Also in the mid-70s some Spiders had a similar relay installed to prevent the car from starting if the seat belt was not engaged in its receiver. These relays were large rectangle shaped metal encased about 3 inches long and 2 inches high.
So most Spiders did not have factory installed relays between the ignition switch and the starter solenoid.

[RRoller123]

Interesting! And the belt stuff has pretty much all much been removed.

[DieselSpider]

Even if it has a factory relay one would want to verify where it gets its power from. Most I fear would still be passing power through the ignition switch and fuse panel.

[spider2081]

Most I fear would still be passing power through the ignition switch and fuse panel.

I am pretty sure the brown wire feeding battery power to the Spider ignition switch is unfused. The red wire powering the coil of the "start" relay from the ignition switch is therefore unfused as it is powered from the brown wire when the ignition switch is in the "start" position. for the automatic transmission "start relay the contact power is unfused 12v direct from battery. I don't have a wire diagram of the seat belt interlock "start" relays contact power origin.