LX 450 battery light is on. (1 Viewer)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Joined
Jan 18, 2020
Threads
2
Messages
11
Location
Fort Worth, Texas
any ideas on what check first? Battery seems strong (fairly new). Runs ok. Gauge is dead in the middle. No change when engine is revved up.
 
Solution
Your alternator is dying/dead.

Got a multi meter? Check the voltage across the battery terminals with the engine off. should be 12.5 ish
Start the rig and take RPMs to 1000-1200, and check the voltage across the terminals, should be 14.6 ish
Your alternator is dying/dead.

Got a multi meter? Check the voltage across the battery terminals with the engine off. should be 12.5 ish
Start the rig and take RPMs to 1000-1200, and check the voltage across the terminals, should be 14.6 ish
 
Solution
any ideas on what check first? Battery seems strong (fairly new). Runs ok. Gauge is dead in the middle. No change when engine is revved up.
Rev the engine over 4500 rpm to see if it makes the light go out and stay out for a while. If so, replace the alternator.

Replace with a Toyota.
 
Rev the engine over 4500 rpm to see if it makes the light go out and stay out for a while. If so, replace the alternator.

Replace with a Toyota.
I am dealing with this right now. Voltage when running is 11.5 and when I do rev motor above 4500 rpm light goes out…does that mean alternator is good but I got a tension problem?
 
I am dealing with this right now. Voltage when running is 11.5 and when I do rev motor above 4500 rpm light goes out…does that mean alternator is good but I got a tension problem?
Nope. It means the voltage regulator is done. It need to be revved like that to re-excite the commutator.

I chose to buy a new one from Toyota. I had nursed mine for two months while on a job site. On my 3-1/2 hour drive home, the light came on 3 times. I called my local dealer and they had it in stock so I picked it up before I went home and had it installed in about an hour.
 
^this

The alternator doesn't reach full capacity until 2500-300 rpm (I forget the actual critical rpm limit). Below the limit, it's really just a trickle charger for the battery, in excess of what's needed to run the demand loads.

What sucks is that you can get a new Toyota alternator for less than the cost of a new voltage regulator for the alternator.
1738002875845.png
 
I had this happen to my 96 model, Red light came on while driving so started checking, cleaning, tightening all the battery connections then did a few tests, no output from the alternator. Had replaced the old alternator (which had been working) as a PM with a new Made in Japan Denso alternator a year or two earlier, WTF?? So got my tools out ready to pull the "bad" alternator and looked down into the engine bay wrench in hand and boom, there was the answer: the harness connector had come loose from the alternator. Plugged it back in, problem solved. FWIW the reason the connector had come loose was because it had a broken latch.

Point is, check the basics first.
 
Last edited:

Users who are viewing this thread

Back
Top Bottom