Wiring problem - alternator ground smoking while cranking (1 Viewer)

[ErikinSC]

Fixed. See below.

I'm going to post this while I search. I have two wires from the alternator frame to the battery negative. I recently had long cranking issues on cold mornings.

I have a #4 ground from battery to alternator. Also have a second ground #12 wire from battery side post to alternator frame. #12 Alternator wire to battery ground has had high current and smoked the insulation clear off. Noticed it this morning when trying to start with motor cold. Saw small amount of smoke in cold air and investigated.

Ground leads were tight both ends.

Was looking through engine compartment and trying to find out why such high current condition existed.

While checking I noticed I have an in connected chassis ground on passenger frame: does it go to starter mounting bolt? How does starter / engine / trans tie back to chassis ground?

It is possible this chassis ground got disconnected during recent clutch and slave cylinder replacement. Appreciate any help or pics thanks

 

[Splangy]

Sounds like you don't have a good ground between your battery/frame/engine. Your engine should be grounded at the starter mouthing bokt. I've never seen anybody hook up an engine ground to their alternator like that before.

 

[ErikinSC]

Last one.
View attachment 275986

This might be my answer. Maybe starting current is running thru the #12 wire and causing my burning insulation issue and hard to start condition. Time to change shirts and crawl under the truck,

 

[ErikinSC]

Sounds like you don't have a good ground between your battery/frame/engine. Your engine should be grounded at the starter mouthing bokt. I've never seen anybody hook up an engine ground to their alternator like that before.

I think the starter ground was left off.... crawling under next to reinstall.

Reinstalled starter to frame ground wire, and PRESTO ! She turns over so much better again.

Now - is the black and yellow ground from battery to alternator bracket even required?

 

[JohnVee]

Erik - it looks like that negative battery clamp is about to snap. Looks like a crack running down the middle. You probably need to run a battery negative to frame ground. Maybe that's where the B/Y goes? But I'm no expert unless I'm looking at my truck and all my notes while I'm on the phone with someone who knows what they're talking about.

 

[bj40green]

Black/Yellow (If it's stock) is a hot wire. Touch it to ground and a fuse will blow (or the fusible link).
ALL GROUND WIRES ARE WHITE/BLACK stripe ! Except the one from the battery negative to chassis, engine, body.

Rudi

 

[lcwizard]

You can't have too many grounds

 

[DPV7070]

Looks like the wires you're using for a ground are pretty corroded. I'd make some new ones...

 

[1973Guppie]

Redo your grounds. Neg batt to frame, frame to engine, engine to body. Use a curved file to clean paint at contact point, a little dialectric grease on ends and contact helps.

 

[Coolerman]

Well I see you figured out the ground wire for the starter was disconnected, but that problem showed a very common problem with FJ40 wiring:

Loosing the main ground from the battery negative to the starter frame forces the electrons to flow through ANY ground that is available! Normally the tiny 18ga regulator ground (grounds the regulator to the alternator) goes up in smoke. The fact you had the two large wires connecting the alternator frame to battery ground actually prevented a really bad ground system meltdown. I just yesterday had to replace half the ground system in a 1978 FJ40 harness that had this very thing happen!

Good insurance to add a large separate ground wire from the alternator frame to the battery negative terminal or to a point on the frame. NOT the engine as the engine is grounded through the main ground and if that is lost....

As was pointed out, a proper ground system is this: Battery negative to point on frame, same point on frame to starter bolt, same point on frame to body. These three grounds are crucial to a healthy Cruiser electrical system!

 

[MoabChris]

Anyone have a pic of this setup?