Big 3 vehicle grounding?

[brimic]

I ran across this concept on a Subaru forum, when I was researching why my headlights burnt out for the 5th time in as many years.
Nobody knows the reason for this problem common problem with subarus, but I saw a few posts talking about voltage spikes and performing a 'big 3 grounding' modification that is apparently used by audiophiles.

From what I can tell:
Run a 1/0 gauge wire from (-) battery to car body, then car body to alternator housing.
Run another 1/0 gauge wire from (+) battery to alternator.

Is there much merit to this or is this similar to fuel line magnets?

[BobR]

Well, it will give you a good ground.

I have no idea if it helps but in my case I replaced the ground wire and positive cable to the starter on my motorcycle with 4/0 cables and it sure does start better/quicker.


bob

[230RN]

I don't know what initiates the failure, but I'm wondering if an oil capacitor, as in a starting capacitor for an electric motor, or a big paper cap, going from + of the lights to chassis, might do the trick.

A spike swamper.

An electrolytic cap might do, but might not charge fast enough to swamp spikes. (You will notice than in many circuits using electrolytics, there's a small non-electrolytic cap across them to deal with filtering higher frequencies in the circuit.)

(Seems to me there's an inductive load somewhere in the vehicle (think relays) which throws spikes when shut down.)

Dogmush?  Comment?

Terry

[dogmush]

Caps could work.  I think I'd want to try and track down what's causing the issue first, as the headlights might be the first symptom of something bigger.  (For example I had three friends with early 2000 Dodge trucks with electrical gremlins.  Turned out that among other things what the bad electrical thin was doing was leaking current into the coolant, and electrolysis was eating the aluminum engine parts pretty quickly.)

The wiring described should give a pretty decent ground, assuming that the car body is free of electrical resistance.  That is where are the bulbs grounded, and how does that go back to the spot where you put the big wire.  Between unibody construction, weld through primer and spot welds, and glue/sealant between parts there's no guarantee that the body itself isn't the issue.  But I haven't really looked an a Subaru's wiring in 25 years, so I could be way off.  I'm just spitballing.


The obvious choice for quick and easy fix, if there are no other symptoms in the car, is to put LED replacement bulbs in it.  The drivers ought to handle any voltage spikes, and the some of the new Halogen replacements actually work pretty well with stock reflectors.

[French G.]

I grounded a Subaru straight from alternator to battery and it seemed to help. About to do it to an electric gremlin ford too.

[brimic]

The wiring described should give a pretty decent ground, assuming that the car body is free of electrical resistance.  That is where are the bulbs grounded, and how does that go back to the spot where you put the big wire.  Between unibody construction, weld through primer and spot welds, and glue/sealant between parts there's no guarantee that the body itself isn't the issue.  But I haven't really looked an a Subaru's wiring in 25 years, so I could be way off.  I'm just spitballing.


The obvious choice for quick and easy fix, if there are no other symptoms in the car, is to put LED replacement bulbs in it.  The drivers ought to handle any voltage spikes, and the some of the new Halogen replacements actually work pretty well with stock reflectors.

Headlights, and up until at least recent years, head gaskets, are a pretty ubiquitous problem with legacy/outbacks. I've even heard theories about bad grounds, or electrochemical issues as a possible cause for the head gasket problems.

I bought a set of LED lamps, and from what I have heard from others, it is possible to install them, just extremely difficult. I gave an hour long try and gave up, but that was a bitterly cold day I was trying to do the work on. I might give it another go in the spring.

[zahc]

It's not a bad idea. OEM grounds can be skimped on by the MFG like anything else, and bad grounds can cause weird things. I even knew a guy who went through 3 sets of front wheel bearings before he figured out he had a bad ground strap and electric current was running from the engine to the chassis through the front stub-shafts.

[brimic]

It's not a bad idea. OEM grounds can be skimped on by the MFG like anything else, and bad grounds can cause weird things. I even knew a guy who went through 3 sets of front wheel bearings before he figured out he had a bad ground strap and electric current was running from the engine to the chassis through the front stub-shafts.

Holy crap.
How did they even know to diagnose it as an electrical problem?

[dogmush]

Holy crap.
How did they even know to diagnose it as an electrical problem?

I'd imagine that someone that knew what they were looking at looked at the worn bearings and recognized the damage.

That's how I diagnosed the first of the Dodges I mentioned. I was helping a friend change his third or forth waterpump and I looked down at the old one on the bench and recognized what electrolysis damaged looked like because I'm a boat mechanic first.  Then we pulled the heads and it was obvious.  Electrical damage to bearings is pretty common in some motors, and it's pretty distinctive.

[DustinD]

Piston and turbo prop airplanes can have a similar issue with static discharge through bearings.