Need help again on voltage regulator?

Well stuck again, I have a 2003 Toyota Tundra 4.7L V8 SR5 Ext cab 4-door (apparently this is a game changer though I really am not sure why) but I was having battery/alternator issues last week and still trying to prognoses/diagnose the problem this week... I think I have it narrowed down to maybe the voltage regulator connector... maybe? I don’t know I normally deal with airplane engines and our voltage regulators are not enternal as they are on the firewall. I have pictures of the connector and the issues are the alternator will work maybe 2-5 mins after the 1st start of the day or if truck is completely cooled down. Then the battery light comes on and the alternator quits working running solely off battery. The alternator off of the truck has been bench checked and passes but I have not check it while it’s mounted. Any and all info or thoughts ideas are welcome and appreciated as I have to get this finished by Saturday with unfortunately little funds available! Thank you so much!

 

Have you back probe the connection with it on the alternator see if the connection is good? When the light comes on probe the 12 volt side of it see if your getting 13.6 up to 14.2 volts. If not the alternator is bad.

If the alternator is getting HOT it will drop out so the regulator will fail but when it's cold it will work normal. Bad soldier joint some where in the circuit on regulator side.

 

Ok so the last part of the message is a bit confusing if there are bad solder joints will effect what? I’m sorry... and then you said back probe the connection?

 

If there are bad solder joints in the regulator it will make the alternator quit charging when hot. . But when they are cold the regulator will act normal.. I believe this is your case.

As for back probe use a multi meter and probe the wires as the alternator is running see what you getting off the alternator compare it to the schematic.

 

How is your battery Connectors?
Especially the ground that rides on the side of the
block.
I feel you have a bad ground.
(Earth) if you are British

 

@Outbound
@Darkness

 

Ok the truck will not idle without me putting some RPMs to it, will hooking up a battery charger hold it while I check the voltage on these?

 

Are you sure the battery is good? Connection to battery good and clean?

 

Ok so there is a reason the connector burnt up could this be the cause of that? You mentioned the ground that rides on the side of the block... something caused this to happen and changing out the connector will not fix the problem I fear! And btw not British just Texan (though we tend to have a language our own as well)

 

Mike I was getting good readings on the battery but I like the way you think is there something else I can do to test? and have you seen the pics of said connector, I have pics of the male end of the voltage regulator as well! Any help would be much appreciated

 

I will agree with @AV8R4AA check ground connections.. use a ohm meter on volt meter see if you getting resistance some where from block to battery..

 

I would probably start checking and replacing the connections from battery to alternator and all the big ground wires from motor to frame and battery to frame. See if that helps. If your alternator tests fine and battery tests fine, its hopefully a failing connection.

 

I think I still would have started by replacing the Alternator. They are relatively cheap and I don't trust bench tests all that much. It still the simplest explanation.

 

There seems to be a common theme with our alternators/starters ‘bench testing good’, but end up not being so good after all.

Keeping with KISS methods: As the others say, check all connections/grounds/earths and all the little bits first. If that fails, then replace the alternator.

 

Well?

 

My sisters Civic would charge for a few minutes then drop to 12V, I pulled all connections and cleaned and used electrical grease on them and now she charges fine. Something cheap to check, maybe even pull back some of the insulation on the wires and see if there is any corrosion creeping down.

 

I wonder how if her alternator brush has worn out? Its spring loaded and I can envision the brush (towards it end of life) randomly making contact sometimes and others not due to the shortness and non-spring compression.

 

Well, it turned out to be the alternator after all! Stupid bench checks, actually I think it was the voltage regulator but unlike planes (one in a roll for planes on something being conveniently located as this is usually NOT the case) where the voltage regulator is mounted on the firewall, a separate entity all together, whereas on my denso alternator it’s located inside the dang thing as one entity! Never thought I would have figured all of this out if it hadn’t been for y’all! And especially Mike (I cant thank you enough for all the tips, tricks, trades of advice)

 

Oh and there was no contact there because turns out it was only a 3-wire plug! FML! What a pain in the ass trying to find those connectors btw!

 

Haha typical glad you got it figured out!!

 

I won't say it....I won't say it.....

 

Best price for Access Cabs Alternators I could find was from the stealerships. A reman’d alternator runs about $305. A new one costs close to $800 from online stores and stealer.

 

Any idea how dependable the reman'd ones are? I had a reman'd starter put in an Acura once and it died 14 months later. I went new the 2nd time.

Is it a re manufactured Denso?

 

I bought an Ultima 100 amp from O'reilly's. It was roughly $175. Ultima seems to be a good brand and this thing has a lifetime warranty. While it's kind of a pain in the butt to swap out, I know if it dies I will get another for free.

I've only had it on for 6 months, so I can't yet speak to it's longevity. I'm not endorsing this product, just giving my experience so you can weigh your options. I sure hope it lasts a while as I am redoing almost all of this truck and don't want to screw with the alternator anymore!

 

You should post a "how-to" guide for replacing it. Not a ton of info out there on it other than people saying it sucks. Do you have to move the power steering pump to get the alternator out?

 

I've been burnt a couple times on parts store reman alternators and starters. I don't bother any more and buy the new ones.

Dealer reman may be better but I can usually get a new lifetime warranty parts store one for less.

 

Yes I should.

Once you get in there it is pretty self-explanatory. And to answer your question, no you do not have to remove it. I slid mine forward enough to allow me to remove the alternator. You basically swing it to the side to allow the alternator to slide out. I did most of the work from underneath if I remember right.

The video below is of a Sequoia, but it is the same thing. Good concise video. Just be patient and know that it is kind of like a puzzle getting the alternator out and the new one in.

https://www.youtube.com/watch?v=DMRQy5JDZt8

 

Yes. The $305 price was a Toyota (Denso) reman’d Alternator. The earlier 1st Gens Brand New Denso ones are $800! Later 1st Gens new are way less.

I’m open to suggestion. Denso seems like quality. Wondering what the stink is if all the parts are swapped for new?

Definitely would not install off brand junk reman’d.

Not keen on putting in a new off label, but if it is high quality and endorsed I’d consider it as long as there is no ‘retrofitting’ involved. I like plug and play OEM.

 

If you have the time have the oem unit , reman at a local starter and alternator shop... some shops can make the oem units more reliable with stronger parts...

For me I dropped in a AutoZone unit about two years ago on the tundra .. like all AutoZone alternator I have bought are still running 8 years (Tacoma) no problems.. I cant say the same for advance Auto ones they suck.

 

Took some pics of an alternator test with the multi-meter (probes on battery posts in both pics).

Per the 2002 Toy specs, a healthy battery should read (see chart below). This battery is about 6 months old.