Is my alternator about to eat dust?

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Fj moneypit

Fj moneypit

Cubic Zirconia Member
10 Year
Joined
May 11, 2013
Threads
137
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Location
Colorado
Ever since I bought my FJ60 2yrs ago the brake warning light in the dash cluster is always dimly lit at idle but not when driving. Wondering if this is the alternator or battery? The battery has no date marked on it from what I can tell and I was going to replace until I found out that it's a pretty good battery (Napa legend premium 84) and problably has life left I'm guessing. Anyway, If alternator, what is the best replacement? I wouldn't mind having a little more amperage if possible but want plug n play. Thanks.
 
Fj moneypit said:
the brake warning light in the dash cluster is always dimly lit at idle but not when driving. Wondering if this is the alternator or battery?
Click to expand...

Neither.
That is a symptom of a floating ground... aka bad ground connection most likely at a common ground junction.
The brake warning light is supposed to only light brightly when the parking brake handle is pulled or the fluid is low in the MC. It should never be dimly lit.. ever.

Remove the whole instrument cluster/panel and look for a collection of ground wires that terminate at a plastic covered plug thingy. It is taped behind the big wiring harness. The white/black wires are the ground wires. Don't mess with the blue wires. Take a very close look at it with a magnifying glass if need be and examine it carefully for any traces of burning or melted plastic.

-1.webp -2.webp
 
Output Shaft said:
Neither.
That is a symptom of a floating ground... aka bad ground connection most likely at a common ground junction.
The brake warning light is supposed to only light brightly when the parking brake handle is pulled or the fluid is low in the MC. It should never be dimly lit.. ever.

Remove the whole instrument cluster/panel and look for a collection of ground wires that terminate at a plastic covered plug thingy. It is taped behind the big wiring harness. The white/black wires are the ground wires. Don't mess with the blue wires. Take a very close look at it with a magnifying glass if need be and examine it carefully for any traces of burning or melted plastic.

View attachment 1035663 View attachment 1035664
Click to expand...

Damn I was gonna say wire too! I thought a ground wouldn't be as consistent as the symptoms, didn't think about a plugged ground. Luckily I removed the instrument cluster a few days ago to swap for LEDs so I kmow the routine. Thanks again Fred.

Ps: if burnt then what?
 
If this is the problem... with this junction....and burning can be seen, proceed as follows:

First carefully cut off the plastic protective cap on that wire junction. In my picture the plastic cap is orange. It's an insulating cap.
The white and black ground wires are all have tiny female spade connectors on the end of them. They plug into a single mult-male spade junction on the top of the plug thingy. There are two multi male spade caps. Leave the blue wires and blue wire's metal cap alone. Pry up the metal cap/multi-male spade cap thingy of the white/black wires with a very small screw driver. It will extract. Then the female pins will slide right out.

Some guys I've heard then just solder all the white/black wires together. I chose to fix up the junction plugs and re-use the plug.

If the plug can be re-used, burnish the multi-male pronged metal tangs with some very fine emory.. like 1000 grit or so to clean them up.
Then re-crimp all the female connectors a little tighter so they provide a firmer grip to the metal fingers on the cap thingy.
I set a vise grips to the correct spacing, and crushed down the little female pins just a little bit so that they were all the same and slid over the metal fingers with firm friction.

Then re-install the b/w wires back into the plug, re-insert the male cap into all the female plugs..... and wrap the heck out of the thing with 3M Super 33 electric tap, ensuring to form a nice thick cap of tape over the top metal thingy before wrapping it all up.


It worked great for me!

But if this junction is burned, there is a cause for it. One cause for burning this junction is installing new, higher wattage headlamps while using the factory headlamp wiring harness.

Or just a bad connection out of the factory at that spot.
 
I didn't see much with the wires @Output Shaft. Haven't tried to start yet to see if it was loose connection or if problem is still there. Will update.

02c6397b9111044727c67c6d338f2c1c_zpsb0b379ad.jpg


08750c578b297f889742770d20112961_zps0c28d0d5.jpg
 
I don't see burning in those pics.

Since you are in there, it might be a good idea to disassemble that thing and clean it up anyway. Then you'll know for sure. If nothing, at least it's preventative maintenance. The gauge lights travel through that junction to ground.

If that junction looks good, there is another one located on the passenger's side sprouting out of the thick wiring harness.. easy to get to and see once you unwrap some of the black protective wrap.

Also examine all wires for fraying or melting of the insulation.

There are also two other common ground junctions to examine in the cab. These two spots are where ALL the grounds in the cab terminate. They are located on the A-pillar on each side of the car and accessed from the floor looking up.

Check the tightness of the 6mm (10mm hex head) bolt that is holding the several-wire junction. If it is not tight (mine wasn't) remove it, clean it and the wire ring terminal up and reinstall it firmly (but don't freaking over torque it!)

Pics below:

Passenger's side grounding junction

passengers side ground junction.webp


Driver's side A-pillar common ground (blue tape on it). Kinda hard to find/see. Rest head on floor, driver's side and look up with flashlight. This view is from a small camera wedged up in there. The view is not as clear when viewed by eye.
drivers side common ground FJ60 A-pillar.webp


Passenger's side A-pillar common ground (easy to see and get to)
passengers side common ground FJ60 A-pillar.webp


A frayed and corroded wire with melted insulation. Look for stuff like this.
frayed.webp
 
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@Output Shaft I'll check them out! I was surprised how clean all wiring was behind the gauges.
Thanks
 
The last time I thought my alt failed the brake and the other light were lit. I could see there was no charging output as I have an LED voltmeter in the dash.
I replaced the alternator with a used one and it works.
Now tonight both lights are lit again.
Is that a fact that the brake light should NEVER be lit unless the emergency brake is on?
So I have had poor grounds both times?
 
brake light also come if you are low on brake fluid and in my case ( Tencha ) if low vacuum it's detected ..
 
Tapage said:
brake light also come if you are low on brake fluid and in my case ( Tencha ) if low vacuum it's detected ..
Click to expand...

It's not the fluid., the light came on the same time as the other light, and the voltage dropped from 13.5 to under 12.
It definitely coincided with the light and charging.
So, if the brake light cannot come on due to a bad alternator, does it mean it's a ground issue?
 
The handbrake light also serves as an indicator of low brake fluid in the reservoir.

:EDIT: Nevermind. Too slow typing.
 
mrt6644 said:
It's not the fluid., the light came on the same time as the other light, and the voltage dropped from 13.5 to under 12.
It definitely coincided with the light and charging.
So, if the brake light cannot come on due to a bad alternator, does it mean it's a ground issue?
Click to expand...


I just started having the same issue only at idle. I can tell the blower fan slows, lights dim, etc.. all indicating an overall loss of voltage when the alt and parking brake lights come on but maybe that loss of voltage exacerbates a pending ground issue. Either way it sounds like I too will be needing a new alternator soon.
 
I have had a bad master cap do the same.

Before replacing the alt, try a new OEM voltage regulator, pretty cheap and even if that not the issue you will need one with a new alt anyway.
 
Well it turns out it was the alternator that went bad.
I started thinking that the 2 lights being on meant something else, but for several manufacturers, when both batt and brake light are on it means there is no charging or a bad alt.
Contrary to what everyone says here, I bought a Duralast from Autozone.
1- I don't have time to get the parts and rebuild it. I need this vehicle for day to day transportation.
2-I can always rebuild the bad one.
3-the Duralast comes with a lifetime warranty. Can't beat that.
And last, as some say here, the oem alternator is not so great.
I've gone through 2 in 2 years.
 
mrt6644 said:
Well it turns out it was the alternator that went bad.
I started thinking that the 2 lights being on meant something else, but for several manufacturers, when both batt and brake light are on it means there is no charging or a bad alt.
Contrary to what everyone says here, I bought a Duralast from Autozone.
1- I don't have time to get the parts and rebuild it. I need this vehicle for day to day transportation.
2-I can always rebuild the bad one.
3-the Duralast comes with a lifetime warranty. Can't beat that.
And last, as some say here, the oem alternator is not so great.
I've gone through 2 in 2 years.
Click to expand...


You don't happen to have the part number do you? I am in the same situation, I think my Alt is going bad (low volts, under 10v when lights are running) And I have never replaced it, so I just wanted to swap it out so I don't have to worry about the Alt being a factor. This is my daily driver, I can't pull the OEM one out and have it rebuilt without something else to replace it with. So if you have the part number that would be great, did it bolt in? Or did you have to do some sort of bracket?
 
Rube said:
@Output Shaft
Think I have a similar issue. Am I headed in he correct spot or do I need to access the harness before it splits off the wires to the instrument panel and heater switch?

View attachment 1906149
Click to expand...
I believe that common ground terminal is taped to the outside of the main wire bundle. On the backside of it. Dig around, you will see the distinctive shape.
 
Resurrecting this in hopes I'm just not looking in the right place or hadn't moved the right thing out of the way. I looked and felt underneath on my driver's side of my 62 to find the A-pillar chassis ground and inspect it for any corrosion, but no luck. Am I correct in assuming it's in the same place in the US spec 62 as it is in the 60? I looked up and felt (as best I could) behind the bundles of wires alongside the dash frame and near the fuse box, but couldn't locate it.

Edit: I found it. Yeah, it's awful. Talk about tearing up your hands to get to it.
 
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