I have an 89 4runner 3.0 v6 and just came home from camping today. I pulled it in the drive to unload and when I started it up to move it out of the drive the AT oil temp light, the parking break light and battery light all came on.

It looks like the parking break light and battery light are an indication that my altenator went out? Can anyone confirm this before I spend the money on a new one?

Also why i was camping I popped the hood and noticed that my reserve tank for my radiator was almost empty. I put just a couple ounces of water in it just in case for the drive back. Did not go to the low mark so I dont think it could have the possibility of being over filled but not sure why that light is on too. I do have a trans cooler (that was installed already why I bought the truck) so not sure if the faulty altenator triggered that light on as well. Any help and advice would be much appreciated!!

Bad alt for sure. Start up, check voltage at battery-at least 13.25v or higher. Let truck run, shut off check voltage at batt at least 12v.

But Im willing to bet you 100 bucks the alt is bad,


Double check trans fluid as well as coolant. Coolant starts disappearing you have a leak or a bad head gasket thats eating it

I checked the trans fluid a month ago and it looked right at the full level and was still nice a red. I checked the coolant just at the top of the radiator and didnt see any black spots or any color other than the bright green. It is just suspicious that all three lights came on at the same time.

Don't know if you've got this fixed but. It's probably your alternator or something seriously wrong with your battery that alt volt regulator cannot cope with intermittent problem (this happened to me this week- battery post broken, acid leaking).

On 22RE, and probably on your V6, too..
See Charging System Explained and schematic below:



If alternator is not putting out approx between 13.5 and 14.5V (depends on temp), Alt "L" output will go low. This output is connected to negative side of Charge error, A/T Oil Temp and Brake error lights. Why the heck all three beats me.

This low voltage will provide "ground" to that negative side and cause all three lights to come one. Confusing I know, but that's how Toyota engineered it. It takes experience or understanding of the schematic to know that if all three come on, it's probably a false alarm for the A/T Oil Temp and the Brakes.

Just one of those things They wanted to get your attention.

It did get the OP`s attention!!

It is only with a charging system issue you get all 3 lights.

Since I have no Auto Trannies I am not sure but the brake problem light does not trip the charge light on any of my 5 speeds.

Yep, and confuse all who see all those three errors.
Toyota is fond of that; On 4th gen Runners fuel cap left open will also trigger VSC error, not related to fuel issue.

Correct, There are diodes there to prevent AT oil temp and brake errors from tripping charge error.

I think it is geared towards the type that goes to the quicky lube for oil changes and the dealer for tire rotation .

Agree Toyota's gotta feed it's stealers - LOL!