Ok to start with, I burnt up an alternator in the mud a couple weeks ago on my 94 with a 22re.

I swapped in another I had layin around that came from a 93

all worked fine but now occasionally when I'm driving the volt gauge cranks to 18 and the battery light comes on, when it does this I have turned the heater fan on and in a few seconds the gauge levels back out

should i be worried? As far as I know the alternator is just factory, I'm just afraid this will fry the trucks electronics if I let it go too long

 

yes worry. overcharging can damage electronics, boil batteries, etc. your voltage regulator is faulty. since your alternator is 18 years old I'd replace with a quality rebuilt unit.

 

X2, the extra voltage can do a lot of damage if you let it go for too long. I would ditch the one you have now and just get a new or rebuilt one like quasi said.

 

Check your actual voltage with a load meter/volt meter at the battery to make sure its actually that much voltage in the system (gauge could be off).

If it is, change it soon unless you like power washing acid out of your engine bay. Also put a roll of TP in your truck, when batteries go boom they can be sudden and loud.

 

If I test the battery directly what kind amps/ volts would be too much?

 

With the truck running you should only have about 14 volts
With the truck off you should have about 12 volts

 

Just to be clear is the gauge on the instrument panel amps or volts?

 

on 94 its volt, and yes rebuild it or change it out, or u will be not happy having to replace the ecu also.

 

Thanks for the advice

 

That I am not sure about because I don't have a factory volt/amp gauge....

I did install an aftermarket voltometer so I know that mine is in volts.

I would assume that the factory gauge would be volts though. Maybe someone else who knows more about it can chime in.

 

haha oops...justin beat me to it

 

Its volts. You dont see many amp gauges anymore, most people dont understand amps anyway.

Crank your truck, stick a volt meter or battery tester on the battery posts. At idle with nothing on (radio, wipers, headlights) you can read as high as 15.5 volts.

IF that things is up in the 16 + range, you more than likely have a bad voltage regulator in your alt.

 

It sounds like it's only hitting the high voltage when the engine is above idle, possibly higher RPM - just replace it. I had the same thing happen to me years ago, but it was only at higher RPM before I shifted - cheap way to increase the brightness of the headlights, I thought they were gonna pop

 

He still needs to test, incase his gauge is off he might be replacing an alt for no reason.

 

Testing is good, but I doubt the gauge and the battery light would both go wrong at the same time - batt light will come on for an under- or over-charge condition. Since it's intermittent, if he wants to test, it sounds like it would have to be done while driving since there's no mention of the gauge or light acting up at idle. In which case the OP could run the test leads out to the battery or just test system voltage from the cigarette lighter (yes, it might be a volt less than battery V, but overcharging will still be obvious)

 

I have a similar problem with my volt gauge. The needle is high all the time (at idle and while driving, it is the same). I checked the battery with a tester while the engine was off and while idling. When off, the tester read 13.4V and while idling it read 14.4V. This seems to be around the range that yall have said was normal, but the reading on the gauge has me worried, and the cigarette lighter has stopped working (the fuse seems to be fine). Or am I just fretting too much (I'm a newbie, just got my first Toyota pickup about a month ago)? Any advice would be greatly appreciated... don't have much experience working on cars, but am excited to learn!

 

The alternator will put out a ton of volts if allowed to. It needs to be regulated to keep it at a safe level for you truck and the components in it. The battery is really a huge resistor for the alternator and "tells" it what it needs as far as power to replenish and also run the trucks components.

If the regulator inside the alternator is bad it will run unregulated and put out massive amount of volts. If you have a modern stereo, the protection will kick in and it will shut down. Does this happen?

Often times, the cable that runs to the battery from the alternator can corrode under the insulation where you cannot see it. This will allow the alternator to pump up the voltage as it is getting no resistance from the battery. You could check this cable by cutting the insulation back an inch or so and take a look for white corrosion.

A good running system will have a running at idle voltage of about 13.8v and a non running voltage of 11-12.

Likely your alternator's regulator is bad which means the whole thing has to be replaced, or rebuilt.

 

I recently came up with a "solution" to my volt meter and oil pressure gauge "problems." I bought an owner's manual off of ebay for my truck (1993) and it had some pictures of how the gauges should look. According to the owner's manual, my volt meter is operating withing the "normal range" and the fact that my oil pressure gauge moved from lower during idle to higher during driving seems to be normal as well. This may be common knowledge, but for me, I just learned something new.


volt meter


oil pressure gauge

 

Hello, I just recently installed an SR5 cluster that has a voltage meter, I am new to this cluster and the meter. The gauge seems to be reading high in my opinion. It only looks this high at higher rpms, or while actually driving. It does go down to about what I guess it should be when its at idle. Does this look normal?

 

Just get a test meter and measure voltage at the battery whilst running the truck. Measure at idle and while revving.

If voltage does not go above 14.6 or below 13.6 volts at any point, you're fine.