Electrovalve Shorting the Circuit

[micktierney]

The first thing I did this Spring was take my '71 fixer upper to "the best mechanic you know, to replace the timing belt". This was the first bit of sage advice that I was able to take with my new and instantly loved Fiat. The driver's side floor is falling out and there's loads of other details to play with but first things first I'm just ready to take her for a ride.

So to that end I pulled out of the shop (the guy who owns the shop has a '71 as well I learned) with new belts, expert timing, a set of $60 radials, and a new second gear. As well as an electrical issue.

Very long story short, I've checked and traced every wire on the circuit, which includes the brake lights, turn signals, reverse lights, every gauge, and the electric fan switch... And the electrovalve?! This thing has one wire but can kill the car?

This wire is at the transmission mount for the circuit. And my question is can I cut the sonofabitch?

I haven't been able to really take the car out all summer. I have gotten to know the wiring pretty well but I'm ready to move on. Or should I bring it back to the mechanics to pull out the tranny again to fix the wire and keep the valve working. Does high rev in 3rd and 4th do anything good for the engine?

[micktierney]

PS, aside from creating a wiring issue (or two, but who can blame them... I probably heard dozens of times when I told people I'd found myself a classic sports car, "Fiat, eh?? Don't those have a lot of electrical problems? It's an old car so no big deal...) the mechanic did a killer job on the gears. I've owned 3 manuals, most recently a 2003 Mazda Protege ('91 Nissan - '66 Mustang). I love the feel of the 124. Best clutch of anything I've ever driven.

[spider2081]

I have never read how this circuit is suppose to operate. I have a wire diagram for a 1970 Spider USA version so I am not positive it is the same as your car.

The diagram I have shows the transmission switch switches a "ground" related to 3&4th gears. I think its grounded in those gears but not sure. This transmission switch is then wired to a switch activated with the clutch pedal. It then goes to the valve. Not knowing what your symptom of a problem is I don't think cutting the wire between the clutch switch and the transmission switch will cure your problem. The wire can only fail by being "open" which is what cutting it would do. The other way it could fail is to be "shorted" to ground all the time. If the diagram symbols are correct the clutch pedal would also have to be pushed in for the wire you want to cut to be in the circuit.
Maybe someone with experience could explain what the electrovalve is used for. I was thinking it has something to do with the idle speed.

[micktierney]

As far as I have been able to gather, Auto Ricambi was very helpful, the electrovalve is exactly that, it causes high idle in 3rd and 4th gear in an environment friendly function burning up the fuel more fully by keeping rpms high.

So far I have disconnected everything one at a time, but each time as soon as I drop into third the fuse pops.

[spider2081]

That is a big help for me to understand what is happening. If my diagram is correct you have 2 wires on the electrovalve One is light blue with a black trace. This wire is power from fuse 9. For the fuse to blow when the gray wire on the transmission 3 and 4th gear switch is closed means the switch and its wire are doing what they are suppose to do. They are switching a ground. to the electrovalve connector. The electrovalve is an electrical magnet like a relay. So it needs power on one side and ground on the other to do its thing. If when you provide this the fuse blows either the fuse is the wrong value or the valve has an internal short. Can you test the valve by using an inline fuse the value you have in the car and connecting it to the battery terminals making jumper wires. In other words use just the battery for voltage and make up your own wires fuse and connect to the valve electrical terminals.

[micktierney]

It's for on the right fuse. And I have checked and cleaned all other connections on the fuse. The last test was to unplug the gray wire at the clutch pedal. The fuse blows shifting into third not even rolling. Snap, the instant the gear engages.

My neighbor explained to me how the electrovalve on a racing bike he used to ride worked. It kicked in in 5th and 6th gear to keep the rpms high so the motor didn't stall on high speed corners. He couldn't remember how the circuit works though. Does the switch on the 124 open or close the circuit when engaged?

How would I wire the switch to the battery? What would that tell me? My hope is that I can just replace the wire without having to take the transmission apart.

[micktierney]

Or better yet just cut it.

[spider2081]

If the electrovalve has a connector on it what happens if you simply disconnect it? It sounds to me like either there is a short, light blue/white wire touching the white/black wire near or at the connector or the electrovalve has an internal short. If you disconnect the valve and the fuse still blows the problem short needs to be close to the connection. If with the valve disconnected the fuse does not blow, then I really think the valve is defective and has an internal short. Why cut a wire if you can just disconnect the valve??

[DieselSpider]

As far as I understand the valve when activated supplies engine vacuum to the high idle pot on the carburetor. If the valve has a dead short it will blow fuses whenever its engaged. The gent who replaced the timing belt along with doing all the other work probably hooked things up incorrectly or created a short when he removed the transmission and replaced second gear. He should fix his mistake.

Give the mechanic who put in the new second gear and messed up an opportunity to make it right.

[micktierney]

DieselSpider I think that's what my next step will be. Disconnecting the valve itself didn't work so the issue as best my limited electrical experience can tell is with the switch at the tranny. My only remaining concern is that the switch itself isn't bad and it's just the the hookup. Will post the outcome in a few weeks. Thanks for the help guys!

[spider2081]

Do you back up lights work??
If the transmission was out of the car I think the back up light switch and the electrovalve switch were disconnected. I also think they are both on the same fuse. Possible if the wires were for the switches at the transmission were swapped this could be the problem. The back-up light switch should have 2 wire on it, a orange/white wire (power from fuse) and a white wire that goes to the back up light. The electrovalve switch should have one white/black wire on it. If the orange/white wire is on t he electrovalve switch that would cause your problem.

[micktierney]

After some careful consultation with my mechanic we cut the gray wire at the switch on the tranny. Problem solved. At least so far. Gotta replace the gas tank now.

[spider2081]

Great that for now your fuse is not blowing.
I re-read you posts and see you disconnected the wire at the clutch pedal and the fuse still blew. That seems to indicate the switch on the transmission was still connected to the fuse.
One would think if you had a grey wire on the transmission 3&4 switch that would be the correct wire. However if you disconnected the wire at the clutch pedal and the fuse still blew I think it could be the incorrect wire even though its the right color.
Do your back up lights work??

[micktierney]

They don't work. Hmmm, so all of this may have been the result if the mechanic hooking up the wrong wires eh?

[spider2081]

I confused with the wire colors you are stating and the wire diagram however I have seen many situations wihere the wire diagram for a Fiat Spider shows different colors that what the car actually has. This difference is not that someone changed something it is the way it left the factory.
Power for your back up lights comes from the same fuse that powers your electrovalve. The back up power wire goes directly from the fuse to the back up light switch. When you put the car in reverse the switch switches that power to the back up light bulbs. If that wire is connected to your 3 & 4th gear switch it will blow the fuse every time you put the car in 3 or 4th gear. The 3 &4th gear switch switches to ground when you are in those gears.
On many of the Spiders these wire connections can be accessed by pulling up the wood dress piece where the gear shift lever is. I think you can visually and physically see what wire come from the 2 switches and identify them. To identify the cars wires is more challenging. with the wires disconnected from the switches, one wire comes from the back up lights. One wire comes directly from the fuse. One wire is coming from the electrovalve through the clutch pedal. If you have a volt meter one of wires will have voltage on it regardless of the clutch pedal position. That wire should power the back up light switch. Anothe wire will have voltage on it depending on the clutch pedal position. That wire should connect to the 3 & 4th gear switch. The remaining wire connects to the remaining wire on the back up light switch.
I hope this helps. Post more if you have a problem