1986 Yota 4Runner.

So, When I have been driving with my lights on in the dark(because why would you do it during the day?) for about 5 minutes, the dash lights begin acting funky...

Whenever I hit the turn signal the dash lights and clock will dim in concert with the turn signal. This happens with both sides. The dimming stops and the lights glow nice and bright once I throttle it up a bit or pull away from the light and begin driving.

I tested the alternator and it is reading 14.8+ volts idle, under a load with lights on, radio on, heater blower on and turn signals on it actually reads higher, uploads of 15.8v!

The battery, while truck is off is reading a pretty standard 12.4 or 12.8(don't remember which). I'll also note that the battery was corrosion free when I bought it. It has since developed wet looking areas around the positive terminal and corrosion.

This seems extremely high to me. But, I am relatively new to 4Runners and I am still chasing the click-nostart issue also.

Sounds to me like the alternator's regulator is toast. Any ideas?

 

Sounds like you have a over charging condition.

If you still have the original Denso Alternator you might thing about having it rebuilt .

Last I checked the price for the Voltage regulator which is internal was like 3/4 the price of a complete rebuild.

 

You read that at battery POST also? If so, then yes, overcharging.
If "S" wire has bad connection between battery and alt it could cause that.
Could it just be a wiring problem? Many old trucks had been hacked.

Look at my Charging system explained post for wire colors.
To eliminate doubt on wiring:
1) Remove plug in back of alt. CAREFULLY note down which pin each wire color goes.
2) Get 1/4-inch female spade connectors and crimp to test wires.
3) Connect "S" (where THIN white wire goes into alt connector) and "IG" (where red wire goes into alt connector) DIRECTLY to battery POSITIVE.
4) Run engine, and monitor voltage BOTH at screw terminal of alt and at battery POST. They should almost be the same. If not, thick white "B" wire is bad.


1986 huh? How long have you been chasing that issue? Got half-hour, some wire, fuse and soldering supplies? Claim my new year present to you here

 

I'll double check the POST reading while under load when I get home. I wanna say it was reading the same, but I was reading a lot of variations of under load and not, so I may be confused.

As for the link, I did add a relay, as you noted there was not one on my 86 automatic. I used a 1978 Ford starter relay as recommended by KidV in his Final Fix thread. I sanded down the fender well and mounted it directly to it near the same spot he did. The relay was definitely engaging, as it was not a quiet click. It was startlingly loud actually. Though, with the direct juice it would still not start. So I reversed the relay install, super easy to do, and tried a straight jumper line of single core 10 gauge wire from starter to batt positive. It had worked previously, though it did not this time so it may have been a fluke.

I plugged everything back to normal. Key cycled a few times and it, as usual, eventually started right up without a hitch like nothing was wrong. I then told my g/f how much Toyota can sometimes annoy me(PG Version).

I have not replaced the contacts yet. I ordered those from 4Crawler today about an hour ago. Hoping it's the original denso and the PO did not already attempt a starter reman replacement. Haven't pulled it yet, as this is my Daily Driver, so I'll pull it when the contacts come in. If it turns out it's already a reman I'll bite the bullet and order a new denso off Ebay.

 

Unfortunately, little ole southern NM doesn't seem to have a joint that can rebuild my alternator. As an example, The Yota dealer here told me to just go to car quest for the starter contacts, as that's where they get them from and Carquest told me they don't have them. So I ordered them from 4Crawler. Probably a better quality product anyways.

 

Autozone has rebuilt alternators for about $115.

This place https://www.aspwholesale.com/repair-...60a-p8541.html offers a rebuild kit for about $60

This video isn't too bad (earlier version of Denso alternator.)

But before you do any of that, DO check for an open S wire. RAD4runner explained it well.

 

COOL. IF a known good relay or connecting the male spade terminal at starter solenoid still does not consistently cause a good crank, yes most likely your solenoid contacts are bad.
Best of luck.