Ground wire by engine hook fj40

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michaelharrisco

michaelharrisco

10 Year 15 Year
Joined
Jul 18, 2010
Threads
107
Messages
485
Location
Raleigh, NC
Does anyone know what the ground wire goes to coming off the front engine hook on fj40?

See pic.

I have an alternator issue going on. Dealer has a new one on order but I sure would like to confirm if I have an issue or not.

Plan on testing alternator this week but this mysterious ground wire got me curious.

Let me know if you know what it is.

IMG_20140512_074433071.webp
 
That is probably just an auxiliary ground that someone put in trying to work out an electrical gremlin.
 
Where does it go from and too ? Does it go to the battery ? If so leave it on. I do 3 grounds when i build my wires. Frame / body / engine or drivetrain somewhere. Can never have too many grounds on a vehicle.
 
Black
krzyabncanuck said:
Also what color of wire is it ? White with a black strip ? If so that is a factory ground wire.
Click to expand...

Black wire.

The problem is it goes from engine to now nowhere so I'm worried it used to go to batt or alternator.

Main thing trying to get batt recharging and not sure if I have a bad alternator.

When I went to take a look under the hood I saw this wire going to nowhere.
 
Thought it was just me.
 
I'm going to look at all this closer tonight and / or tomorrow. Will update, but if there was an obvious answer to what that gnd wire went to I wanted to know.

I'm not convinced I have a bad alt yet but I do know my batt is good and it isn't getting charged.

More to come
 
JohnVee said:
Have you measured the voltage at the alt or the battery while holding about 1500 rpm? You should see about 14.6 at the alt and less at the battery due to voltage drop in the wiring. This assumes a working alternator.


...via IH8MUD app
Click to expand...
Yes I have. Alt is def not sending charge to batt. At this point I'm trying to figure out if the alt is bad or I have some weird problem (ie why I org asked about the random ground going to no where).

Worse case come Fri I go spend $80 at dealer for new alt and install it and see what happens.

I was looking for a break from working on the cruiser but with this...i got to get it back running since it is a mode of transportation for me
 
My junk isn't wired up like yours so I can't give a play by play of what to do. I'd find the schematic, trace the wires connected to the alternator and check their other terminal ends. I wanna say one wire from alt connects to one leg of the ammeter?

Carry jumper cables or a jump box and go to the parts store. I'd rule out the obvious then buy an alternator. If it doesn't solve the problem at least you have a known good spare.
 
JohnVee said:
My junk isn't wired up like yours so I can't give a play by play of what to do. I'd find the schematic, trace the wires connected to the alternator and check their other terminal ends. I wanna say one wire from alt connects to one leg of the ammeter?

Carry jumper cables or a jump box and go to the parts store. I'd rule out the obvious then buy an alternator. If it doesn't solve the problem at least you have a known good spare.
Click to expand...
I'm fairly sure the odd wire broke off from under the oil pressure sensor. Be nice to know from someone else if I need 2 wires coming off the bottom of that thing. It could be an additional gnd PO added. At this point I tend to agree that just replacing the alt and seeing prob goes away might be good plan. If the obvious looks good and the alt ain't sending a charge I don't know what else to do.
 
Confirmed: bad alternator

Going to look at the mysterious gnd later on after I get it running good again. If oil pres gauge isn't working I will know that is what is was for
 
Everything is good now, but I do have a new related question.

Is it normal at idle for lights to dim a bit? I've noticed a few times now that the turn signals even stop blinking at idle.

The alt is def charging now so I'm good there.

What causes the dim at idle? Idle set too low? Perhaps just the deal with driving a 30+ year old truck?
 
Dim at idle is common. Either the alternator isn't charging at that RPM or it's just due to voltage drop in the wiring. Read this...http://www.madelectrical.com/electricaltech/brighter-headlights.shtml Relays will help. There's also info on that site about wiring an idiot light to the alternator so you know if it's charging or not. I did that because I'm paranoid. I also wired in a voltmeter instead of the ammeter. He's got a lot of good information if you're willing to spend the time reading. Very helpful on the phone, too, if you can reach him. Old school guy.
 
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