Intermittent Electrical Issue... Input greatly appreciated and needed. (1 Viewer)

[REZARF]

I am having a tough time finding and fixing a problem that first reared it's head about a year ago.

Issue: Sometimes I get NOTHING from the factory electrical system. It's hit or miss, I get 100% function about 90% of the time or more.

Back story: 1976 FJ40 quit on me last summer for the first time ever in 20 years of owning and driving it. It was my DD for over 15 years and still sees 1,000's of miles a year both on and off road. It only quit once while driving and running, the rest of the time it cuts out while trying to start or before I turn the key.

What I know:

• When it happens, I get nothing, no starter, no lights, no fan, no nothing electrical. For example, I turned it over the other day and it spun 2-3 times and died before catching.
• Entire aux fuse system works 100%
• Battery is strong 12.5v at rest 14v when idling.
• Terminals are tight
• Good power (albiet less voltage ~10v) at the fuse panel.

What I have done:

• I have an 85 FJ60 electrical dizzy and ignitor, tied into the factory 76 wiring.
• I have replaced the ignition switch with OEM.
• I have created new grounds from the battery for frame, body and engine (not the starter to frame). This made a BIG difference in the way everything was working- brighter lights etc. and it seemed to have fixed the problem until this past week.
• I have jumped the igniter coil to isolate it from the system without change.

My best guess:

• Some sort of ground issue? But I thought that the new braided line I made from the battery to the cowl would take care of it. I have not cleaned the ground at the frame on the passenger side frame rail, nor the rear ground.
• Maybe jump a ground to the fuse panel to test it?
• Someone has mentioned a dead or dying battery cell causing the issue but I have ALWAYS shown a full 12.5v at rest.

I am wide open to ideas at this point.

Thoughts?

 

[Martyt]

Not sure about your model year, but on a 69’ I would suspect the connections at the amp meter.

 

[peesalot]

Try taking the fuse panel off the kick panel and look at the back of it, sometimes they get corroded on the back and it causes weird issues. Friend of mine had a 70 that did same thing, he found fiddling with the fuse block on the kick panel fixed it so finally removed it and cleaned it all up, worked. Just a thought. One other suggestion is the ign. switch, contacts wear and the main on contact will exhibit the behavior you are experiencing.

 

[spotcruiser]

2nd the fuse block. Clean it up or get a new one from CityRacer.

 

[REZARF]

Interesting I did see a little corrosion on the back side of the fuse block between the plastic shield and the actual terminals. The shield of plastic is flaking off... I guess I'll tear into that next. Thanks for the tip... anything else stick out to anyone?

 

[REZARF]

One other suggestion is the ign. switch, contacts wear and the main on contact will exhibit the behavior you are experiencing.

I replaced with new OEM so I am hoping this is ruled out. But I agree, it does seem like it would be suspect. I have checked it with a voltmeter and it checked out... twice over the past year.

 

[REZARF]

I cleaned up the fuse block. Pulled it, scuffed all the terminals, and brushed the contacts front and back with baking soda/water mixture, then cleaned it off with electric parts cleaner.

No dice...

 

[Solace in Solitude]

Do you have a fusible link?

Sounds like the connectors between the fusible link and the pigtail, on the the battery positive... or the fusible link and the harness on the PS fender apron... or the fusible link needs to be replaced?

Check the pigtail connectors, at the battery+ and st the fusible link.

Check the connectors, at the harness.

Check the connectors on the fusible link.

My guess... the connection at the wiring harness is loose and you’re periodically losing it... maybe after a bump, or it’s overheating.

 

[REZARF]

Do you have a fusible link?

Sounds like the connectors between the fusible link and the pigtail, on the the battery positive... or the fusible link and the harness on the PS fender apron... or the fusible link needs to be replaced?

Check the pigtail connectors, at the battery+ and st the fusible link.

Check the connectors, at the harness.

Check the connectors on the fusible link.

My guess... the connection at the wiring harness is loose and you’re periodically losing it... maybe after a bump, or it’s overheating.

Thanks @Solace in Solitude for the help man.

I have removed the fusible link... and swapped in a traditional fuse.

Again, I am getting power to the fuse panel but no lights, no starter no accessory 12v outlet, nothing.

 

[AlaskanWheeler]

Fuses are still good, +12 volts on both sides? Also measure your ground to ground connections, you shouldn't see much of anything, but if you do, it'll be telling indication of your system.

 

[REZARF]

Thanks @AlaskanWheeler yeah, 12v both sides of each fuse. Gotta’ chase the grounds, tonight I hope to clean up the three main harness grounds and wiggle the connections and clean each one up, shine them, grease them with some dielectric grease.

I’ll report back tomorrow.

 

[Solace in Solitude]

When I bought my 40, I had the same issue. I finally unwrapped the harness wrap, where the fusible link connected to the harness, on the PS apron.

The connector, to the harness was loose and corroded. I bought new connectors from Mark (coolerman) and fixed it for good.

So, my issue was with connectors, not with the fusible link.

I would check this connection before moving on.

What color wire measures ~10v at the fuse panel?

What powers your aux fuse panel? e.g. what color wire does it tie into?

 

[Solace in Solitude]

Clean that main ground to the PS framerail, behind the PS front tire.

I think you said you haven’t cleaned it.

I don’t think that’s your problem, but it would be better cleaned.

 

[REZARF]

When I bought my 40, I had the same issue. I finally unwrapped the harness wrap, where the fusible link connected to the harness, on the PS apron.

The connector, to the harness was loose and corroded. I bought new connectors from Mark (coolerman) and fixed it for good.

So, my issue was with connectors, not with the fusible link.

I would check this connection before moving on.

What color wire measures ~10v at the fuse panel?

What powers your aux fuse panel? e.g. what color wire does it tie into?

I removed the entire fusible link and replaced with a traditional in line fuse.

I have pulled lots of connectors and everything is shiny on the inside, I am pretty religious about using dielectric grease and have been for years. My connections in general are really clean.

I have two white with blue stripe wires coming into the OEM fuse panel. Both are reading 10v +/- .5v

My aux panel is run off a dedicated 6 gauge wire off the battery. It is entirely separate from the OEM panel. Everything down stream of that panel is 100% good to go.

Clean that main ground to the PS framerail, behind the PS front tire.

I think you said you haven’t cleaned it.

I don’t think that’s your problem, but it would be better cleaned.

Today I crawled under and addressed both the mid frame and rear grounds. I wired wheeled them. Used a fresh star washer and coated with dielectric grease for the future.

The front "main" ground frame connection was recently (6 months ago) cleaned to bare steel, new star washers were installed along with a new battery ground cable, engine ground cable and body ground cable (to the cowl). That connection is still clean and tight. The two grounds I hadn't addressed were the mid and rear frame grounds, but I got to those today and made sure they were good to go.







Does anyone know if there is more than one fusible link on the main harness? If so, any idea where it lives?

 

[White Stripe]

Just one fusible link. I would carry a test light like this...
Lisle 29050 Digital Circuit Tester 3-30V
When it happens hook up your test light and see where your loss of power is. That's what I would do. U can hook it up to hot and check for grounds, and hook it to ground and check for positive power. It will also tell u if u have a weak connection which will show up as low voltage. The other thing u can do is voltage drop test all the circuits. U will find a ton of YouTube videos on voltage drop testing. A circuit with unusual voltage drop may give a clue to a bad connection. Got a pic of your battery terminals? U get my email btw?

 

[Pin_Head]

Use a fusible link, not a regular fuse. You don’t want to lose all power instantly with a short because it could be dangerous. A fusible link takes longer to blow.

Don’t confuse voltage with power. For power, you need both voltage and amp current flowing. Measuring voltage on an open circuit can fool you into thinking it is good. Turn it on so that there is some kind of load and then see what the voltage is. If there is a bad connection the voltage will drop.

 

[bikersmurf]

Use a fusible link, not a regular fuse. You don’t want to lose all power instantly with a short because it could be dangerous. A fusible link takes longer to blow.

Don’t confuse voltage with power. For power, you need both voltage and amp current flowing. Measuring voltage on an open circuit can fool you into thinking it is good. Turn it on so that there is some kind of load and then see what the voltage is. If there is a bad connection the voltage will drop.

Do you know the amperage rating of the fusible link for an Fj40? I’ve got an aftermarket harness that was pulled from a 40 because it kept blowing a 25 A main fuse... unfortunately it was parted out because he couldn’t get it running again with the new harness. Based on your recommendation it should be a fusible link instead.


OP, here’s a thread that may help with ground related issues:
Never underestimate the importance of a ground

 

[3_puppies]

I didn't see it mentioned, you said you replaced and cleaned the grounds. how about the positive from battery to starter?

I'm with @Pin_Head on having voltage but no amps being an issue.

 

[Pin_Head]

Because so many different circuits lose power, including ones that are constant power without the key on, you know that the problem is between the battery ground and the ignition switch. This would include the battery cables, the fusible link, and the amp meter.

 

[REZARF]

Thank you fellas, my late night reading has lead me to try these steps next:

• Clean up/replace battery to starter lead cable. (Needed either way)
• Replace frame to starter ground (made it last night). Need new star washer. It looks rough.
• Buy and install a fusible link. Yank out the fuse off the battery.
• Check the ammeter though I'm not sure what I'm checking for yet other than voltage and amps entering and exiting the unit.
• I bought new military style terminals and will clean up my 20 years of adding and deleting things.
• Burning the 40 to the ground in frustration, if it won't start.

Any help on diagnosing the ammeter would be welcomed. I'm not entirely sure what it does and why.... I just know it moves when my blinkers come on. I assume it measures and displays load on the electrical system?