Where "-" from battery connected to engine?

Gotta love that wiring . . .
Post Reply
KirillZip
Posts: 15
Joined: Thu Jun 10, 2021 3:48 am
Your car is a: 2-0 FIAT TWINCAN on LADA 2103 1973

Where "-" from battery connected to engine?

Post by KirillZip »

Hi!

Where is "-" from battery connected to engine?

I had connection betwin battery and body of the car near headlight (battery i have at right side of car) , and a connection from body to gearbox.

Battery on my car is on the right side - were exhaust is.

Thanks
Nut124
Posts: 748
Joined: Wed Oct 25, 2017 6:39 pm
Your car is a: 1978 124 Spider 1800

Re: Where "-" from battery connected to engine?

Post by Nut124 »

The battery negative should be connected to the metal car frame.

The engine should be also connected to the frame with a ground cable.

Fiat 124's have a ground cable from the bottom of the car to one of the ell housing cover bolts.

These need to be thick, heavy copper cable.
KirillZip
Posts: 15
Joined: Thu Jun 10, 2021 3:48 am
Your car is a: 2-0 FIAT TWINCAN on LADA 2103 1973

Re: Where "-" from battery connected to engine?

Post by KirillZip »

Today cleaned tip of cable under boby to gearbox. Can not tell that it was rust, but at the end of cable (neat tip) it is a bit green.

Problem was that starter was not working. It was rotating very weak, and lamps was die away (as battery as discharged).

I substituted a new starter and a new battery for testing. And arfer I cleaned up cable - it starts (it also was starting if make a direct cable from battety to engine body)

I measured resistance betwin battery "-" and stater body - it is 0.1 Om. I do not know - what it should be

Image

So if cable is not good - car wont start... I guess. But I can no replace it - because from body side it is welded on...
User avatar
aj81spider
Patron 2020
Patron 2020
Posts: 1526
Joined: Fri Mar 11, 2011 9:04 am
Your car is a: 1974 Fiat 124 Spider
Location: Chelmsford, MA

Re: Where "-" from battery connected to engine?

Post by aj81spider »

You can tie another cable in parallel if you're worried about the one you have being bad. However I will say on my meter 0.1 is about the lowest ohm reading I can get. I think the leads connected to each other are close to that.
A.J.

1974 Fiat 124 Spider
2006 Corvette
1981 Spider 2000 (sold 2013 - never should have sold that car)
18Fiatsandcounting
Posts: 3799
Joined: Fri Mar 15, 2019 11:23 pm
Your car is a: 1969 and 1971 124 spiders
Location: San Francisco Bay Area

Re: Where "-" from battery connected to engine?

Post by 18Fiatsandcounting »

Measuring very low resistances (below 0.2 ohm or so) can be very tricky without specialized test equipment. A better way to test a battery / cable connection would be to measure the voltage across that connection as you crank the engine. Perhaps disconnect the ignition coil wire so it won't start and you can measure it for a couple seconds.

Anything more than 0.5 volts would indicate a poor connection. Ideally, the voltage would be zero but that's hard to achieve in practice.

-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: Where "-" from battery connected to engine?

Post by spider2081 »

Measuring very low resistances (below 0.2 ohm or so) can be very tricky without specialized test equipment. A better way to test a battery / cable connection would be to measure the voltage across that connection as you crank the engine. Perhaps disconnect the ignition coil wire so it won't start and you can measure it for a couple seconds.
This is so true. Great point.

An old school test for battery connections is to crank the engine for a few seconds and then feel the battery cables terminals with your bare hand. A warm terminal can indicate a terminal that could use cleaning and tightening.
KirillZip
Posts: 15
Joined: Thu Jun 10, 2021 3:48 am
Your car is a: 2-0 FIAT TWINCAN on LADA 2103 1973

Re: Where "-" from battery connected to engine?

Post by KirillZip »

Thaks a lot. Will try.

This tester I have - it sad that it is a bit exact.

I started this topic - because I can not start engine. So want to fix it
Post Reply