Starter electrical

[Steve124]

I have been having intermittant starter problems in my '72 Spider. I have pulled the starter and bench tested it, it seems to work fine. I'm trying to test the connection from the ignition switch to the starter solenoid. When i turn the key to start, iI get 3.5 volts. Not sure if this is correct or not. I can't find the spec for this, so I don't know if it is correct or not. Can someone tell me if this is the correct voltage?

Thanks, Steve Norheim
1972 124 Spider

[Nut124]

Where are you measuring this at? Should be 12V something at the solenoid vs ground.

Bad battery or bad ign switch can do this. I would also check the engine ground cable.

[18Fiatsandcounting]

I'm trying to test the connection from the ignition switch to the starter solenoid. When i turn the key to start, iI get 3.5 volts. Not sure if this is correct or not. I can't find the spec for this, so I don't know if it is correct or not. Can someone tell me if this is the correct voltage?

As Nut mentioned, it should be 12 volts. Potential causes could be weak battery, bad battery connections, bad ground strap, loose wire connections at the back of the ignition switch, or a failing ignition switch. All are pretty common, but I'd start with the battery and its connections first, then move to the ignition switch if those aren't the problem.

-Bryan

[Steve124]

Sometimes i do get 12 volts and the engine starts with no problem. Then it will spin the starter but not engage the flywheel. I replaced the ignition switch recently because the old one failed while driving causing the starter motor to run continuously with the engine running, but not engaging the flywheel. The old ignition switch had expanded/bubbled the insulation around the contacts. I replaced the switch and it worked fine for a while and now is periodically not spinning the motor but not engaging the flywheel. This is when I discovered the low voltage issue. Is there something else that could cause the new ignition switch to fail like the old one?

[TX82FIAT]

I would test voltage at a couple different grounding points. Assuming you have 12+ volts across the battery then I would think it is a ground or connection issue robbing you of volts on that starter circuit. If not in the circuit or the ignition switch, then I'd suspect the start of a failing starter motor. However, since you replaced the ignition switch a few months prior to this problem surfacing it might be a voltage drop across the switch. Did you install a Sipea switch or a Lada switch. Was the new ignition switch new or used. Also, prior to replacing the ignition switch you may have had a problem or developed a problem with your starter if it continually span while not engaged. Next time it does not engage, get a 2 X 4 and hit the starter motor and then re-try. If it starts after a wack, it may be the start of a bad starter motor.

[Steve124]

The replacement switch was new from Auto Recombi. It said Lada on the key.

[TX82FIAT]

The Lada switches are prone to failure. However, that is pretty fast for a switch to fail. I'm leaning towards a connection, ground/circuit issue or the starter. I'm sure this is frustrating and will take a lot of testing and tracing to solve.

[spider2081]

As others have stated 3.5 volts is too low. I would expect the voltage on the red "start" wire for the starter solenoid to read battery voltage if it is disconnected from the starter solenoid. It should measure something greater than 10 VDC when connected to the solenoid and the ignition key in the start position.
One often over looked and troublesome connection that can contribute to your issue is a 3 pin connector located on in the area of the horn compressor on the driver side fender well. This connector will have the red wire that connects the ignition switch to the starter solenoid and a brown wire that connects the battery voltage to the ignition switch. In some cases there is a 3rd wire that is black also in the connector. It also connects the battery to the ignition switch. This connector is sometime the cause of the infamous "click" some Spider owners experience.

[Steve124]

I looked at the 3 prong plug. With the ignition on, I got 12 volts on the Brown wire, but only .78 volts on the black wire. I would have expected 12 volts. Maybe this is where my issue is.

[18Fiatsandcounting]

I looked at the 3 prong plug. With the ignition on, I got 12 volts on the Brown wire, but only .78 volts on the black wire. I would have expected 12 volts. Maybe this is where my issue is.

Which side of the plug did you see 0.78 volts on the black wire? The side going to the starter motor, or the side going back to the wiring harness?

The black wire coming from the starter motor should connect to the large cable from the battery to the starter, so this black wire should have +12V on it at all times (even with ignition switched off). The black wire going into the wiring harness shouldn't have any voltage on it, although you might see some residual voltage, especially if the ignition is on.

-Bryan

[85redpini]

The replacement switch was new from Auto Recombi. It said Lada on the key.

those work just fine better quality than the fiat original, and you can buy just the electrical part unlike the oem fiat ones

[85redpini]

The Lada switches are prone to failure. However, that is pretty fast for a switch to fail. I'm leaning towards a connection, ground/circuit issue or the starter. I'm sure this is frustrating and will take a lot of testing and tracing to solve.

that is not true. i have sold hundreds of them
all the vendors switches come from lada, it is not like the Italians are making them for a 40 year old limited production car. you should be appreciative that the vendors make the effort to source parts no longer available from fiat or other sources

[TX82FIAT]

that is not true. i have sold hundreds of them
all the vendors switches come from lada, it is not like the Italians are making them for a 40 year old limited production car. you should be appreciative that the vendors make the effort to source parts no longer available from fiat or other sources

I'm thankful there are replacement switches and vendors that sell them. Your right, it's very hard if not impossible to find an original Italian Sepea switch. The Lada switch is a good alternative to something that is very hard to find. With that said, I stand by the statement that a good Sepea switch is better than a new Lada switch based on my experience replacing ignition switches in three Spiders over the last 36 years as well as discussions with other FIAT owners about their LADA switch. The point I'm making is moot as the LADA switches are readily available and work until they don't. A much better alternative is to install the ignition relay to take load off the switch and prolong its life. The point in offering help is the ignition switch could be part of the electrical issue. However, in this case I would lean towards a connection.

[spider2081]

Sorry I just reread this post.

The three pin connector should have a brown and a black wire that are connected to the batteries + terminal at the starter solenoid. The brown wire powers the ignition switch. The black wire powers fuse 1. The circuits connected to fuse 1 are the horn and the radiator coolant fan.
There should be a red wire in the 3 pin connector also. This red wire activates the starter when the ignition switch is in the "start" position.
When the ignition switch is in the "start" position all three wires should measure battery voltage and the engine should be cranking over. The voltage should be more than 10 volts.
With the 3 pin connector connected, putting one meter lead on the red wire and one on the brown wire with the ignition switch is in the "start" position would test the connections in the starter solenoid circuit. The voltage displayed should be less than 1 volt.

[Steve124]

I'm still having the same problems. Turn key to start, starter spins but doesn't engage the flywheel. I have 2 starters, an old one (probably 70s vintage) and a newer gear reduction starter. Both work when tested on bench with the car's battery and bendex extends gear. In the car, battery has 12.5 volts. At the starter, I have 12.5 volts. At the three wire plug, both sides, Black wire is 12.5, Red wire is 0.00 and Brown is 12.5. Turning the key to start, the red wire shows 10.4 volts at the 3 prong connection and at the end that connects to the solenoid. Red and black are 12+ volts. I checked the Red and Brown wires, as suggested, with the ignition at start and got .52 volts.

Not sure what to do next.