Alternator questions

My truck has died a few times lately, charging system's not working. If I put a battery with 13.6v in and fire it up it's at 12v at idle. I have no battery indicator on the dash, it doesn't flash for a second at startup, nothing. It will run for a while off of a charged battery but the ABS/brake light eventually comes on, then the check engine light for 0130, loses power, then the airbag light comes on right before it dies. I'm not sure if I've ever seen a batt light, but I see where it is, next to check eng.

I pulled the alternator, 90a Bosch. Cleaned any corrosion/dirt, reassembled and reinstalled it, nothing. If I buy an alternator, I'm going to upgrade. I'm worried because of the no-dash-light thing. Did a previous owner just kill the dash led/wire, or is this the symptom of a bigger problem? Anybody have any ideas for something I overlooked? 120a fuse looks fine.

 

Take the alt to get tested, most parts stores do it free.

 

I usually replace with an OE or equal.

 

Tried that when it was out,
Parts store nor the wrecker had a bench test rig, but a Canadian tire about 45m away could have done it. I tried putting it back in, still no charge. Wrecker wants $175 for a used one, best price I could get on a new 130a was $265. The no-dash-light worries me though. If I plug in a new alt it's non-returnable, and the 130a is special order cash-up-front.

 

In previous Toyota builds I’ve swapped my low output alternator with the highest OEM equivalent output alternator and it has been plug and play.

In your case there is a 130amp OEM version you could upgrade to. Not certain the connectors are the same on a 2nd gen but it seems extremely likely. Almost a 50% boost in output without using expensive high output alternators.

 

Both (tow package 130 amp and non tow package 100 amp) 2nd Gen Alts have the same connectors.

http://densoautoparts.com/find-my-part

 

Can you order from rockauto.com?

 

Thanks for the heads up, there's tons of good auto wrecker photos on eBay. The 130's are the same plug, I've been telling all the parts houses I have a tow package. I'm going to have to limp it around like this for a week, I can plug it in at work

no credit card, and I'm in Canada. I can probably use someone's PayPal to buy something on eBay, there's lots of 130a-200a-240a ones on there.

I'd like to diagnose the problem better, dash light (or lack of) worries me. Like maybe the alternator won't get an "activate" signal if the trucks not getting a "battery drain" light. Everything worked fine a week ago but I don't know if the dash light did or not.

When everything's off (lights, ignition) and I hook up the battery there's a decent spark. I think there's a short somewhere, but it could be inside the alt? 120a alt fuse looks ok as does the 7.5a alt.s fuse.

 

Does that mean it's a hybrid, like those electric cars you see plugged in at fancy places lol. You said at idle the voltage is at 12v, what about at higher RPMs? Try starting it and then disconnect the battery while it's running, if it dies the Alt is definitely not working. There is a voltage sense wire that I've heard people talk about but I'm not sure that it applies to your issue because it's just measuring battery voltage.

 

Sometimes the battery lights just don't work, try to disconnect the battery with it running, if it dies you know the alternator is bad. I think your making a bigger deal out of the light not working.

Good luck

 

In america land of throw away parts sure, but he's in the desolate frozen north.

 

Do not do this, unless you want to get new electronic components. This is one of the worst advice I've seen on this forum.

OP, if there is an electric shop near you, they should be able to rebuild your alt. They will bench test your alt first to confirm what is broken, if anything, then fix it and provide a warranty. Maybe only 90 days or so, but I've had good results from these perishing breed of mechanics.

 

So what your saying is I need to go get new electronic components because I swapped dead batteries with a buddy whose alternator went out?

@BamaToy1997 care to weigh in?

 

Nay, I'm saying don't disconnect the battery cables while the car is running.

 

Which is exactly what we did to put my charged battery in his truck and his dead battery in mine to charge.

 

That was too risky a move.
http://www.troubleshooters.com/dont_disconnect_battery.htm
http://www.pacificpowerbatteries.com/aboutbatts/car battery faq/carfaq14.html See 14.6
https://www.2carpros.com/questions/...charge-run-car-positive-battery-cable-disconn

 

@MuddyJackson
This thread might help you out

 

Thanks for the diagram Sandman!

The truck dies if I do the old classic disconnect-the-battery test, good advice or not. Dies right away.not even going to click those links Chuy posted.

Somebody pulled me a free GM alt from a 90s truck with similar mounts/pulley, I don't know if it's a cs144 like the ones they're selling for a Tacoma conversion or not, but I'm hoping I can scab it together enough to see if an alt fixes the problem anyway. Worth a shot.

https://www.tacomaworld.com/threads/high-output-alternators-for-1st-gen.499065/
There was one thread on here that said our oem alts put out 20ish amps at idle and the GM one does ~100 idle amps. Plus they're cheap and plentiful, and our alternators are down low where they get wet. I'll get a free one to troubleshoot with tomorrow so I'll see what I can figure out about wiring.

 

It is not always 100%, but it CAN be very dangerous to disconnect the battery with the engine running. The battery acts like a voltage stabilizer. When the battery is disconnected the alternator and vehicle electronics "think" that the battery is heavily discharged, or dead. This results in a much higher output from the alternator. In many, many cases it has resulted in a much higher voltage than is safe for the sensitive electronics of today's modern vehicles. Now it won't do it every time, but you do run a high risk of destroying an ECU, Radio, BCM, or other expensive electronic component by disconnecting the battery with the engine running.

 

Well, glad I know not to do that again, and now why - thanks.

I was driving around for days off battery power, it would run at well under 12v, I was worried about frying something then. Drove around with a spare battery in the back, had to swap them a few times.

The chev cs144 I got was the wrong mounts, I would've had to change belts for it or the 12/6 mount, so I jut bought a Toyota 130a denso alt. Everything works great, 14.4v, re&re took an hour tops and I'm slow. I was super worried that the alt might not be bad, there was 12v to 2 of the 3 small alt harness wires and 10.5v to the other. New alt fixed everything, even the nonexistent battery light on the dash. It flashes up proper for a second on startup like it should. I think it's very strange that instead of the battery light coming on when the alr died, it just stopped working. Oh well, I got a better alternator out of the deal that can keep up with the lights and stereo- mine had 90a Bosch.