Alternator overcharging?

[Youngan]

Hello,

1989 2WD van. Alternator, oil, and radiator lights all come on while driving. Intermittent at first, now all the time. If I turn off the engine and start it back up, problem will not exhibit for several seconds, or perhaps not until I rev it above idle. Voltmeter on the battery shows charging at 16 volts at idle, over 17 when revved.

Could this be anything OTHER than the regulator?

Thanks
Andy

[Stinkaroonie]

Sounds like a regulator, anything over 14 volts is excessive.

[originalkwyjibo]

It's likely the regulator which is internal on these, sort of.

[Flecker]

I had a Christmas light dash prior to repairing the PS leak that went into my Alternator... tested it at 12.5 volts. Ok, it's bad.

So, I ripped everything apart, pulled the Alt. and went through it. It honestly wasn't bad... Fairly clean for it's age (Original ND). Went ahaead and replaced the brushes and Rectifier that seemed suspect. Had it tested at the local parts store and it tested perfect, 14.95 volts on the output.

Went home, put it all back together and got busy with a coolant flush. Trying to rehab this old beast!

Checked the plug, I know it's a known issue.. was good.

Anyhow, while warming the engine for the flush I got the Christmas dash again. Got my meter and to my surprise it's now outputting 17.8 volts. What? LOL...

Any ideas?

And YES, I searched. Thanks!

Edit, how it looked. Before and After

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[Flecker]

Additional info... I did go ahead and flip the high beams on... voltage dropped within range to about 14.9 volts. Still seems a bit high. Exciter wire maybe?


Edit: Just went out and tried to recreate the situation. And now I am thoroughly confused. HA!

I went ahead and started it up and put the voltage meter on the terminals of the battery and it ran a consistent 14.3 volts... fluctuated down to 13.8 when I ran the heater and high beams, then right back up to 14.3~ when I turned off the heater and hi beams. I tested continuity across my sensing wire at the batt., back to the alternator. Rings out good.

I did the research and bought a proper regulator. This one: https://www.amazon.com/gp/product/B000C805XW/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

Suppose it could be malfunctioning intermittently, but I highly doubt it. I did manipulate the wires at the positive side of the terminal prior to the test... will have to look further into it in the AM. Will report back with my findings...

[timsrv]

Check your FL 0.5G fusible link (little round yellow plastic connection in the battery compartment). It's covered in the 1st post of THIS THREAD (https://www.toyotavantech.com/forum/showthread.php?136-The-fusible-link-thread). If it's degraded to the point connection is lost the alternator will go into a "full field" mode and start putting out excessive voltage. Tim

PS: The wire that goes through the yellow FL 0.5G is a sense wire and it continues on to the "S" terminal on the alternator (see pic below). If that circuit is broken anywhere between the battery + terminal and the "S" terminal it would cause the problem you're reporting.

https://i8.photobucket.com/albums/a23/timsrv/TVT%20pics/electrical/alt_diagram_zps907cbf7d.jpg

[Flecker]

8115
Check your FL 0.5G fusible link (little round yellow plastic connection in the battery compartment). It's covered in the 1st post of THIS THREAD (https://www.toyotavantech.com/forum/showthread.php?136-The-fusible-link-thread). If it's degraded to the point connection is lost the alternator will go into a "full field" mode and start putting out excessive voltage. Tim

I appreciate that Tim...

I know that plug for the fusible link is not present... In fact theres a big yeller crimp on connecting what I suspect "used" to be the spot for the original FL. Ha... I am just getting into this, but suspect that may indeed be the issue.

I fiddled with those EXACT wires prior to testing it the last time and the issue of overcharging wasn't present.

I am going through the fusible link thread now and see other issues as well. Time to go through the entire system I think. Ohmed out my main ground and found fault there, fluctuates quite a bit when jiggling it. Ha ha, getting an OLD van and fixing it up is just SUPER fun! :dance2:

Check this out... I have amatuer hour crimped connections, a wire nut! (my personal favorite when rehabbing old cars) And no oem fusible link! Good times! Will fix and report back tomally.

Thanks Man for the help!

Edit: I just went out and tested the "s" (signal wire) and it tested fine through to the terminal... I suspect that the crimp and stak-on though are weak, when I jiggled them I got mixed readings. As usual with these little vans you are pretty much spot on! Will fix tomorrow and make sure I share the results!

[Flecker]

Follow up. Problem/s solved.

After going through ALL the connections I have, with Tim's reccomendations and help, pretty much rewired the ENTIRE battery box. Turns out that my van was hacked at some point in it's life and ALL fusible links were removed, and wires re-routed, wire nutted and hap hazardly scabbed together with crimps creating bad connections due to grease, dirt and improper installation.

After discovering that and a faulty ground, the culprit turned out to be a mixture of a few things. First, the ground to the battery thats runs to the block/ subframe had began to fail. This was replaced where it is bolted on the subframe, just adjacent to the battery compartment. Where I was getting random ohm readings (sometimes good, then above 30 ohm's/ resistance to ground) I now have a solid 0 ohm reading.

The fusible links were cut out at some point and all needed to be replaced.

Side note on fusible links: Toyota has a standard of upsizing wiring at least a gauge size in most of thier vehicles, thus the FL is sized according to the gauge of the wire to be protected.

A quick break down of rating would look like this:

A 12 gauge fusible link is 3.0 sqmm
A 14 gauge fusible link is 2.0 sqmm

A 16 gauge fusible link is 1.0 sqmm (note: Toyota uses a 1.25 sqmm rated for roughly 26 amps, it is hard to find outside of the dealer- upsizing to a 2.0 is a 7.5 amp difference at 33.5 A)
A 18 gauge fusible link is 0.85 sqmm
A 20 gauge fusible link is 0.5 sqmm

And so on.

I spliced in new FL's for the 2.0 rated circuit (8 gauge wire) and the 1.25 rated circuit (10 gauge wire) and routed directly to the battery terminal. The white voltage sensing wire had a weatherproof fuse carrier wired inline with a 15 A fuse installed. The sensing wire at .5 sqmm is rated at 13 A, so it was a rather moot point to hunt down a fusible link for this function.

The results were as expected. Charging happy at 14.3 volts consistently at the battery and 13.4 volts across the harness points I could test. Anyways, all cleaned up, connections greased w/ some dielectric and ready for years more service!


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Cliff notes: For an over charge condition from the alternator, check and verify these things:
Plug from harness at alternator is sound/ not defective.
Regulator is functioning properly (wise to check wiring first!).
Verify Fusible Link .5 is present and working properly, replace if faulty or missing with either a NEW FL or a 15A inline fuse on 14 gauge wire.
Verify ground connection to battery and frame/ engine locations.
Verify charge circuit fuse is good.

Happy vanning!