Topic: Alternator question.

[PETDOC]

I've got 350,000 miles on my '88 4Runner and am on my 4th alternator. The last 3 have been rebuilt models from Advanced Auto. They last about 3-4 years. Lifetime guarantee has been the reason I've stuck with Advanced Auto. My first 3 alternators failed in exactly the same way, i.e., the dash battery and charge lights would illuminate at low rpms and go out at higher rpms. Additionally the voltage would drop when the warning lights were on. Very repeatable.
 My present situation is the dash warning lights illuminate at random and the voltage never drops (Actually after closer observation the voltage needle does drop a little). At times it seems the lights come on when I hit a bump and then go out when I hit another bump. There is no effect of rpms on the lights. I can go 50 miles and see no lights or see them several times. I detached the upper electrical connection to the alternator and thoroughly cleaned it. This had no effect. 
 I think this is a connection issue and not an alternator issue, but my question is........ has anyone had a faulty alternator act like this? I don't want to endlessly pursue a faulty connection when it is the alternator and Advanced Auto will give me another one.

[junya92toy]

Do yourself a favor, get a stock toyota alternator, get new brushes for it, and then done worry about it

[Nimyad]

What he said, or use a gm alternator. But your problem doesn't really sound like a bad alt, I don't think. Sounds like your headlight switch is going bad or is corroded. It's be worth taking a look at that.

[PETDOC [OP]]

What he said, or use a gm alternator. But your problem doesn't really sound like a bad alt, I don't think. Sounds like your headlight switch is going bad or is corroded. It's be worth taking a look at that.

How would a bad headlight switch intermittently activate the battery and brake dash warning lights? headlights work just fine.
I have read that there is a relay mounted behind the glove box that somehow activated the battery and brake warning lights and when it goes bad they can come on intermittently.

[Nimyad]

How would a bad headlight switch intermittently activate the battery and brake dash warning lights? headlights work just fine.
I have read that there is a relay mounted behind the glove box that somehow activated the battery and brake warning lights and when it goes bad they can come on intermittently.

Hahahaha, my bad, that's what I get for skimming. Was just reading you saying lights over and over and assumed headlights lol.

I'd definitely check that relay you're talking about though, sounds more like a relay than a charge issue.

[PETDOC [OP]]

I pulled the alternator off. There was a moderate amount of corrosion around the 3 prong electrical connection that plugs in the back. The alternator tested as good at Advanced Auto. I cleaned up the comnnection and re-installed the alternator. Time will tell, but I believe that is/was the problem. During a 2 day period when it was raining the dash warning lights never came on. I suspect the added moisture increased the contact of the corroded attachment.

[junya92toy]

THey always test good at the parts store, but they are crap

[PETDOC [OP]]

So my warning lights came back on again today and now are staying on for longer periods of time. My plan is to replace the alternator with a re-manufactured Denso first, but I still think the symptoms favor an electrical short and not a failing alternator. The existing alternator is 4 years old and the 2 previous Advanced Auto alternators lasted 4 and 5 years, respectively. If after replacing the alternator I still get warning lights, which is what I expect, I'll start stripping the wiring harness and look into the relay behind the glove box.
 If the new alternator solves the problem I'll take my old alternator back to AA and politely tell them they will no longer get any of my business.

[Cheesemaker]

Get some dialectic grease.  It's for electrical connections and makes them mostly waterproof.   

[junya92toy]

Yes yes yes, I use that on all my connections.

[PETDOC [OP]]

When I removed the alternator I took a tiny drill bit (fit inside the connector) and wrapped a small amount of steel wool around it by running the drill in reverse. I soaked the connector with electrical contact cleaner and ran the steel wool covered drill bit in reverse inside and out until the contact was as good as new. Lastly I cleaned all remnants of steel wool from the connector. It may still be a connector problem, but I don't believe it is due to poor contact. Before connecting the 2 contacts I applied a liberal amount of dielectric grease.
 My present generator, 3 years and 10 months old, is nearing the time when the other 2 Advanced Auto generators failed so I figure replacing it is not a waste of money. When I do replace it I'll strip of the tape around the wires at the 2 connections and see if there are any frayed wires. If not and the new alternator does not cure my dash warning lights I'll go after the relay behind the glove box.
 AA agreed if the alternator tested as bad they would sell me a re-manufactured Denso for the list price (137) minus the price of their lifetime guarantee alternator (70). Since it tested good they were unwilling to do the deal. While I currently don't think a new alternator will solve my problem I'll certainly let AA know if it does and reluctantly give them any future business.
 

[PETDOC [OP]]

I discovered that the relay behind the glove box (Toyota #27790-35010), which when faulty can activate the dash charge and brake warning lights, was only used on '81-83 4 cylinder trucks and some car models of the same vintage.
Other problems cited in threads on illuminated brake/charge warning lights included wire pulling out of the back of 3 prong plug that inserts into back of alternator, improper insertion of that plug, loose alternator belt and broken/frayed wire where the wiring harness crosses the frame of the vehicle.

[PETDOC [OP]]

THey always test good at the parts store, but they are crap

You would be correct.
My rebuilt Denso alternator arrived yesterday so I was going to put it in this morning, but noticed it was damaged. I contacted the sender regarding returning it. I decided to hook up my trailer and get a load of gravel with my old suspect alternator still in the 4runner. About 7 miles from home the voltage indicator blew through the roof. Finally I knew for certain it was the alternator or more specifically the internal voltage regulator. I turned on every power drain I had (high beams, heater full blast, dome light, radio, flashers) and costed down hills in neutral to drop the rpms to get home. There was a moderate amount of battery acid on the top of my battery when I finally arrived. 
 I pulled the alternator and returned to Advanced Auto. They tested it 3 times--always good, and refused to honor their guarantee. I then spoke with the manager who also was opposed to honoring the guarantee. I patiently explained how an alternator with an internal voltage regulator worked and that a defective regulator was the only explanation for the signs exhibited by my 4Runner. The manger very reluctantly allowed me to pay the difference between the rebuilt Denso and the price for a new lifetime guarantee alternator. Alls well that ends well.......... I guess.
 When trying to install the Denso I ran into a slight problem. The internal sleeve on the front mount of the bottom bracket was back a tad too far for the new alternator to fit. I could not budge it and it got dark, so tomorrow I'll try again. Any advice on moving the sleeve would be appreciated.
 

[86bobbedtoy]

you can replace the brushes and regulator inside, really easy
usually the alt is good, just worn out brushed or bad regulator
if my memory is right the alt you are trying to install now is for a few years newer,
however I recall using a grinder and just taking 1/4" off

now all this info is being dug up from 15 years back in my head, good luck

[PETDOC [OP]]

if my memory is right the alt you are trying to install now is for a few years newer,
however I recall using a grinder and just taking 1/4" off

now all this info is being dug up from 15 years back in my head, good luck

Actually the Denso is the OEM alternator. The sleeve in the front bolt hole of the bottom bracket is there I'm sure to take up any space between the bottom of the alternator and the bracket. Trouble is it is a very tight fit and hard to move. I solved my problem with the technique I described in this thread http://board.marlincrawler.com/index.php?topic=91531.0