3 alternators 1 new battery and no luck! 1997 taco

I have read through a number of threads but haven't seen any problems quite like mine.

The background below is the more concise version of a long story:

1997 Tacoma 2.7L.

I replaced my battery about 2 weeks ago when it wouldn't hold a charge. Later, the battery light came on and eventually the truck died. I had the system checked at autozone (after charging the battery) and the alternator was only putting out about 1Amp and the voltage was decreasing as the truck ran at around 11-12V. I put on a new alternator and I had the same problem, so I put on a second alternator. Again, same problem. Fuses are all good. Connections all look good.

According to the local auto repair shop the problem is that I did not buy a brand new alternator from them and that would solve the problem.

After three alternators something else must be wrong. Plus the alternator test off of the truck demonstrates that it works fine.

Has anyone ever seen something like this before from a first gen tacoma?

Any help would be appreciated. Come my way and I'll buy you anything you want to drink.

 

I have a 97 and had to get a new starter.... I thought it was the batter but nope

 

Unless the starter is engaging(or energized) while your flywheel is already spinning..I don't see what a starter has to do with a voltage drop across your charging circuit. ^

If that was the case, sounds like something went haywire...


It could be alot of things,to be honest..I couldn't even think of what else it could be.

Do you have a sound system? What about anything auxiliary powered through other circuits?

 

I had something similar. The first time battery light was on, the alternator failed. I pulled the negative off the battery while idle and everything shutdown. Replaced alternator with kragen part# 13885. Second day, alternator failed again. This time I pulled the negative and car kept running. However, it was overcharging the whole system. Blew my dome light, a couple fuses, battery fluid spewing and spun my electric fan super fast.

I ended up returning that alternator and went with another one rated at 140amps shipped to me from Ace Alternators and Starters off ebay. So far everything is 100%.

Have you tried taking off the negative terminal while truck is running to see if you can isolate the possible problem?

Maybe a short somewhere? Bad ground? has to be some type of break in the circuit if alternators testing out fine. (be weary of alternator tests as your alternator can function differently at different rpms and I don't think the bench test system spins the pulley that fast.)

 

voltage regulator?

 

fireturk41: The voltage regulator is apparently in the alternator itself.

UndefinedTaco: I do have an amp that is wired to the battery. However it has been fine for over a year now. I also added a ground from the battery to frame to ensure proper groundage.

Us3r: I haven't done the battery cable removal check. What would that tell me exactly?

A mechanic I spoke with mentioned that older model Nissan trucks will do the same thing if the battery-indicator lightbulb on the dash goes out. I haven't checked this either. The truck died in a parking lot across town tonight as I was on my way to a different automotive shop.

 

On a system that is working correctly, where the alt is putting out 14 VDC, when you pull the negative off the bat, the engine will continue to run.

For troubleshooting, this separates the bat from the alt.

 

it sounds like the alternator is not charging the system while the car is running. do you happen to have under-drive pulleys? try disconnecting all the wiring from the battery that's related to the amp and test what voltage its showing while running. did you do any new mods before all this happened? maybe check for cracked or loose wires going to and coming from the alternator.

 

I don't think it has an under-drive pulley. Perhaps it does...the belt spins on the alternator, a crankshaft pulley and another pulley that doesn't seem to connect to anything else. Nope not mods and I haven't been listening to the stereo for weeks before this started.

An associate mentioned that on one of the other pulleys there could be a "shiv" or clutch as he called it that could have gotten worn out and the belt isn't spinning fast enough to generate enough voltage or amperage.

 

i'm thinking the amp is the culprit. even though you're not using your system, disconnect the power wires at the battery that's coming from the amp and test what voltage the battery is putting out when the truck is running. do this and report back.

 

I disconnected the amp and I am getting about 12.1 volts (with a fully charged battery). I also disconnected the negatve cable and the truck immediately died. I noticed the battery indicator light doesnt come on when you turn the key to on, so I checked the light bulb and 7.5 amp fuse under the hood. Everything is fine. Is it possible to test the pigtail that connects to the alternator for proper voltage?

 

if you removed the negative cable from battery and your truck died. Than your alternator is faulty.

 

you've narrowed it down to your alternator not charging for some reason. i'm assuming you're testing the battery voltage at idle. have someone rev it up to 2,200-2,500rpm while you check to see what the battery is putting out. it should read close to 14v.

 

I did rev it to around 3k but the voltage did not go up. It didn't change at all. I am pretty certain that the alternator is okay (since this is the third one I've tried with the same result) but for some reason in the truck it is not working correctly within the electrical system. That's why I'm wondering if some controlling element is failing. Like I said the battery light doesn't come on which should point to a problem. I disconnected the pigtail coming in but it didn't do anything to the voltage or engine. Should it have? I wonder if there is a way to test the signal coming from the ECM.

 

I don't have Toyota specific experience but it is possible that there is a bad fusible link where the wires are hooked up at the back of the alternator. Had one bad On a vette and caused all kinds of problems with charging system. Good luck.

 

I would check the wires coming from the alt. One may be broken, partially melted, or the fuseable link is bad. Ohm that wire out. If it reads close to 0 ohms it's OK. When doing this test wiggle and twist the wire.

 

Could you tell me, does the main wire that comes off the alternator connect to the battery, starter, or both? Is the fusible link closer to the alternator or battery? Also, do the 3 wires connected to the back of the alternator come straight from the ECU?

 

Check the fuses and everything connected to your alternator!

 

this and double check all your grounds starting with the alt., engine,....

 

I have finally fixed the truck!

Everyone was correct in that something was wrong with one of the wires of the alternator. I attempted to ohm out the wires coming off the alternator, but I was having trouble getting my multimeter prong to touch the inside of the connector. Plus, a mechanic told me it was bad to pierce the jacket of the wires coming off because then water would have an access point.

So I sent it over to my Toyota dealer and they figured it out within an hour: Two of the three wires had become disconnected at the plug and were shorting. You could see that the jacket was burned from electricity arching the gap.