I run a Scanguage full-time in my '01 2.7 4x4 Taco and I noticed the other day while riding down the highway that my voltage seemed pretty low. I had already been driving for about 35 minutes on the highway with the headlights off and hardly any other auxiliary electronic accessories on (radio, HVAC fan, etc), so my battery should have been already topped off... but my cruising voltage on the highway was fluctuating between 13.2 to 13.3, occasionally dropping momentarily to 13.1. I don't recall ever seeing it get that low before and I could have sworn it was usually around 13.5-13.8 while cruising and around 13.8 to 14.0 when first starting the truck up. I don't generally drive the truck too much at all during this time of year so I'm having a hard time remembering if I've ever seen it go that low before.
I don't have the FSM PDF handy at the moment (at work), and was curious if this seems unusually low for operating voltage? Possibly my alternator/voltage regulator are nearing their end of service life.
Anyone care to share what their normal voltage is on a 3RZ after having been driving for a while with very little load on the system?
I've never seen my voltage go higher than 14.2 during the 12 years I've had my truck. Just curious if the methods of reading voltage could be resulting in anomalies between our measurements.
I was curious about this so I looked at the 96 FSM for the 3RZ. Should be the same for your 01, I think. According to the FSM when the engine is cold and at idle voltage should be between 14 and 15 at terminal B on the generator. At operating temps the acceptable range drops to 13.5 to 14.3. That is when tested at terminal B on the generator with no load and at idle. I would expect some loss on the way to your scan gauge, but even so your numbers do sound a bit low. In the FSM the test under load (hi beams on, heater fan on high, and 2000 RPM) only looks at Amps, not voltage, suggesting that there are too many variables to properly evaluate the voltage under load. Under load the amps should be above 30 and below 10 with no load (at idle with everything off). Does your scan gauge show amps?
The FSM points to a bad regulator if the voltage is high and a bad generator if the voltage is low, of course you need to check the battery and all the connections before jumping to conclusions about your generator being bad.
The numbers and testing procedure is the same for the 5VZ. On my 97 with the 5VZ I monitor my voltage on my aftermarket radio display. I look for 14.3 when cold and 13.8 when hot. Different system so perhaps not helpful, I don't have a scan gauge.
I've driven the truck twice since I originally noticed what could be perceived as potentially problematic voltage. Both times were short 10 minute drives but I kept my eye on the voltage and it was basically between 13.7 and 14.0 the entire time. Have you ever heard of an alternator that gets weak the longer it's been running?... such that (for example) it would start out normal and then gradually drop its voltage over the course of a 2 hour drive, presumably as it built up heat. Thoughts on this?
I'll be taking it on about an hour long drive tomorrow night and will keep a close eye on the voltage the entire time to see if it does anything erratic.
Battery is fine. The alternator definitely hasn't been exposed to any real serious mud pretty much ever. I took the truck out this weekend quite a bit and my voltage was always 13.6 to 14.0. IIRC it was extremely hot out on the day that I initially noticed the voltage being low and I was in some heavy stop and go traffic for the first half of my drive, although the voltage drop occured in the second portion of my drive where I was just highway cruising at maybe 2500 RPM. I'll take a look at my alternator next time I get a chance and make sure there isn't a bees nest or something else blocking airflow into it.
Looks about a volt low. Maybe your brushes are on the way out. I'd double check with a real voltmeter just to be sure before I started taking things apart. It could just be a loose or bad connections somewhere.
Mine started running a tad low a week or so ago and I was thinking brushes or something else since my regulator is a welder and I have a dual battery setup. When I checked under the hood the voltage to the first battery was normal but the voltage at the main battery was running a tad low. I traced it to a slightly loose ground on the battery isolator. One tweak with an allen wrench put it right back to normal.
Already clean and tight and the truck fires up with tons of power when I crank it.
My alternator belt always squeals for about 5-10 seconds when I first start the truck up and my Scangauge doesn't turn on until it catches. I wonder if maybe that belt was slipping a tiny bit when it was really hot out after the belt warmed up and became more flexible. I'll take a look at the condition of the belt tomorrow and check the tension. I'd say this belt is about 3 years old, but probably only has about 15-20K miles on it max. It's just one of those shitty Dayco belts from Advance Auto though which seem to be exceedingly prone to slipping in my personal experience of late on cold starts in several different vehicles.
I really haven't seen the voltage go as low as that one time again since then although it's never above 13.9. Seems to consistently float from 13.7 to 13.9 over the past 2 weekends worth of driving after me keeping close tabs on it throughout that duration.
Find out why the belt is slipping and fix it. That is never a good thing and needs immediate attention. You probably need a new belt if it has been slipping for very long. Again you need 14 something not 13 something if your meter is any good.
Just drove about 150 miles straight with the GF in my truck up to Maine for a long weekend and voltage was 13.8-14.0 the entire way. No real dips or spikes. I will probably replace the alternator belt when I get home just to be safe since it's not that new and has slipped on cold starts for a while for the first 5 or so seconds.
On an unrelated note.. I just recently had my tires dismounted, and the interior rim surfaces sanded and bead sealed with a fresh balance(all 4 for only 28 bucks too!). Tires holding air perfectly now and she's running smooth as silk down the highway on the 32's and getting almost 24 MPG. I love this frickin truck.
Does anyone know who makes the OEM belts for our trucks?
I thought Bando made the ones used on Nissans, but not sure about Toyota.
Any thoughts on Bando vs Dayco vs Mitsuboshi vs OEM? I currently have Dayco on my car and truck and both squeal like a stuck pig on startup.... pretty annoying.
Thanks. I'm contemplating between Bando and Mitsuboshi belts right now.
The Dayco belts seem to last quite a while but their grip is terrible. They seem to slip for me in both warm and cold weather but significantly more in cold. I'm pretty sure my tension is set right too.
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