toyrunner83

I picked up a 90 pickup over the weekend to fix up and I've got all the bugs worked out but one. I found the issue when I reconnected the amplifier for the sub that the previous owner had disconnected from the battery. It worked fine so I took off for a ride and cranked the system to check it out and the engine started sputtering when the amp would draw power. I unhooked the amp and assumed it was just too much for the system. Then at night with the headlights, heater fan, and wipers going I turned the turn signal on and the engine started sputtering every time the signal light came on. After playing with it I've found with the headlights on if I take the heater fan straight to high at idle the engine dies completely, and sputters badly while driving. Also the gauges, all of them from what I have noticed jump up under load and drop back to normal position after the accessory causing the problem is turned back off. Specifically the temp gauge jumps up incrementally with every step of the heater switch while the headlights are also on. Basically the charging system can't keep up with normal operation of accessories. I contacted the previous owner who said he replaced the alternator recently in an attempt to fix the issue and it didn't. I cleaned the battery terminals and tightened the alternator belt as it was slipping a bit a start up and I thought it may be slipping under load as well and nothing has caused any improvement with the issue. Does the 90 still have an external voltage regulator and could that be the problem? The charge light hasn't come on and the voltage gauge is always in the normal operating zone. Thanks for any help and sorry for the book!!

toyrunner83

the I contact in the title is an error if a mod could fix that I would appreciate it.

Leviticus6432

It would be weird if it was caused by the amp... I had a hifonics titan in my 95 4runner for years. It was fused at 120amps... and it pulled about half It didn't cause any problems with my electrical system that I know of.

Leviticus6432

Did you check all fuses? charging fuses and am fuses mainly Get your battery and alt tested? don't know how your batt would crank it over tho and you have all these other problems....

toyrunner83

It operates fine under most conditions, with the headlights off it will power the fan on full or the amp at any volume. Starts fine everytime, holds a charge fine, it just can't keep up with everything at the same time with our without the amp connected. With the amp completely disconnected I can't run the headlights and the fan on full without the engine sputtering. I haven't checked fuses, I notice there is one fuse labeled "charge" in the power dist box under the hood, haven't even looked at the fuse panel inside the truck. I also haven't checked the battery output or alternator as they seem to function properly under most circumstances and the voltage meter in the dash show normal 13-14 volt range.

4wd4fun

c;heck the big wire to the fuses under the hood for any corrosion
and check the wire on the stud on the alternator too

delmert

check the amps and volts off the alt with and without a load.. if it doesnt go up with a load on it your regulator might not be working right... not sure on the 90s but if its an external it fould be mounted on the side wall and be labled..
If there's an o'reillys near they can do a test on your system while runnin... for free... might tell ya somethin...

wyoming9

iTrader: (1)

Break out the multimeter and do some checking just because the gauge says it is in the normal range it may not be.

It is perhaps time to upgrade the wire coming off the Alternator B terminal they get brittle with age.

Look at the ground cables they were small from the factory I always upgrade these on every Toyota 4x4 that comes through my place.

Have you checked to see just how much this amp is drawing??

Hadmatt54

If you were just having your battery go dead or your lights go dim then I'd probably think that your problem is in the charge circuit, but where it's affecting your other electrical accessories:-
I'd say that you have a ground problem. I had a car a few years ago that would do similiar things with the wipers, gauges, etc., it was caused by a bad dash ground and this was a North American vehicle that had switched power. Japanese are switched ground sounds like the circuit that is causing you the grief is looking for its ground through other accessories

TNRabbit

Agree with the multitude of answers above. It's either a bad battery cell, alternator on the way out, or wiring between any of these.

worshipmentor

iTrader: (3)

IMHO it appears to be NOT on the charging side of the circuit but on the accessory side. A multimeter on the alternator output side of the main fuse would be a good place to start. If power is still good there when you get the "sputtering" issue then conitnue to check upstream til you see an drop.
Realistically, as mentioned earlier by our learned colleague, ITS MORE THAN LIKELY A GROUND ISSUE. These older Toys are notorious for this. I always run extra bonding wires (aviation term for grounds) from the battery to multiple points with good, clean, treated connections that are SOLDERED not crimped. I would especially check the ground from the battery to the engine block itself.
Hope you find it, gremlins are NO FUN!

toyrunner83

Thanks for the tips guys, I went through the grounds again and found the issue. There was a second much smaller wire connected to the negative battery terminal that ran back along the firewall to the driver side of the truck. I had previously assumed it was running to the cab for the stereo or something but.. it was attached to three separate wires, 1 large black one and 1 one white with a stripe coming out of a wire loom below the airbox and one that was attached to a very small oe black box with two wires attached to it, almost looked like a computer chip or something probably a resistor or relay of some sort mounted to the driver inner fender. Any way, They were obviously grounds and after playing around I figured out they were responsible for pretty much everything but the starter. All the interior accessories, all lighting, and the ignition all relying on a very small wire for ground. I split them up and ran multiple grounds to the body and battery and now all is well. Glad to have that figured out it was driving me crazy.