Alternator Voltage is too High -- Battery Light Flickers

[98Base4R]

Battery light started to flicker and/or stay on for a second or two, so I replaced it with a Carquest 80A from Adv Auto. Adv Auto's testing machine was down that day, so I wasn't able to test battery or alternator I was replacing.

I kept the alternator I removed, didn't turn it in for the core charge until I was sure the new Carquest would work.

Put the Carquest unit on, light still flickers. Maybe a little more, or a little less, hard to tell.

Took the original alternator to AZ, along with the battery. Both test "Good" according to AZ.

Took the T4R (with replacement Carquest) to an alternator starter shop. They gave it the $25 once over, and said the light didn't come on during the test drive. If you aren't looking, you won't see it. Alternator shop's recommendation was to avoid Carquest alternators. Offered to disassemble original alternator to look for issues.

Went through diagnostics from online source. Found the source on a tag in the alternator box, the one that says "STOP: Don't return this part until you talk to us!" Unfortunately, they don't answer the phone. Diagnostics include positive cable voltage drop, negative cable voltage drop, engine running voltage, engine off voltage.

Replaced Carquest alternator with AZ Duralast 80A. Kept Carquest to return to Adv Auto. Alternator light flickers. Hooked up Fluke meter again, and watched meter while watching battery light. The battery light flashes when the voltage goes over 15.5V. Using the MIN/MAX/AVG function, I saw a few spikes over 16V. So the battery light is doing its job, but the voltage regulator is not.

 

[98Base4R]

At this point, should I:

A. Keep playing parts store roulette and try for another part (maybe from NAPA this time?)

B. Get the original alternator rebuilt with a new voltage regulator, and insist that it test out under 15.5V before re-installing

C. Order a new alternator from Camelback

Other?

Thanks!

 

[theesotericone]

I'd take that battery out and have it tested by a different shop.

The chances of getting 2 bad voltage regulators in a row are pretty slim. If the batteries got a dead cell the alt will keep full field to try and charge it. That will show voltages above 14.5. I's also be running a continuity check in the wires that plug into the alt harness. A break in one of those can also throw a higher charge state.

How old is the current battery?

 

[98Base4R]

The battery is a Deka is is marked Nov 2016.

The 4Runner hasn't run for since Friday. With the engine off I turned the headlights on bright to break up the battery's surface charge. Headlights back off, the voltage was 12.4V.

I have hooked up a battery charger to see if the charge rate seems normal for a "good" battery, or if it continues to charge at a high rate.

Thanks!

 

[98Base4R]

With charger hooked up on 15A setting, voltage climbed to 15.75 in 10 minutes before I stopped it.

That seems to agree with your bad battery theory, right?

Thanks!

 

[98Base4R]

I put the charger on the Sienna battery and at first it acted similar to the 4Runner, slowly climbing to almost 15.5V, but then it seemed to stabilize and dropped down under 15V.

I swapped the battery from the Sienna to the 4Runner and the battery light is off.... thanks for having me look closer at the battery!

 

[19963.4lsr5]

I put the charger on the Sienna battery and at first it acted similar to the 4Runner, slowly climbing to almost 15.5V, but then it seemed to stabilize and dropped down under 15V.



I swapped the battery from the Sienna to the 4Runner and the battery light is off.... thanks for having me look closer at the battery!

Drive it around a few days making sure your light doesn't come back on.

What is your voltage with this different battery?

I keep a voltmeter plugged into my cig lighter to let me know how things are going with the charging system.


Sent from my iPhone using Tapatalk

 

[Johnnie]

bad connection

try checking the cable going from fuse box under the hood down to the alternator in particular the connection at the fuse box, you will have to take off the lid. look for corrosion, loose connection and signs of overheating. this same problem may occur on other cables and cause the same problem. basically it would cause a high resistance connection. my runner was getting hot enough that the plastic around the connection was deforming/melting

 

[98Base4R]

Resolved: White Wire was broken

After more days of battery light flicker, the light came on and stayed on. There is a white wire that runs from the 3 pin connector on the back of the alternator to a 4 pin connector at the base of the under hood fuse box. I dissected all of the electrical tape and loom to expose that wire, and cut most of it out. Stripping the ends of the removed wire, there was no continuity.

I spliced in a new white wire, soldering the ends. I used a $12 soldering iron from Wal-Mart, some heat shrink, new wire loom, electrical tape, etc. If I can do it, you can do it. No more battery light!

 

[theesotericone]

Stripping the ends of the removed wire, there was no continuity!

Glad you found it. That's why I suggested looking at the battery and the wiring upthread. Here's a not so quick read of me going through a very similar thing with my old 88 Toyo Van.

I'm "thetoaster" on that site. Long story short my van was silver and had sun fade on the roof that made it look like a giant toaster when viewed from above. So I went with it. lol

Start reading at post #20.

https://www.toyotavantech.com/forum/showthread.php?717-Van-down-electrical

 

[Drcoffee]

This exact thing happened to our 99 T4r. The voltage spiked and dash light went out. Voltage was 16v if I recall. The white wire had a nick in the insulation and the copper wire was green with corrosion and finally broke. Its a Cheap fix to splice in a section of new wire and shrink wrap to keep water out.

 

[caprirs1]

battery light flicker

I currently have a 2001 that has similar issue have had two alternators on it and had original rebuilt because it tested bad still doing same thing so now i will look into these wires to see if this is my problem thank you will follow up