Bill Edgar

My truck has had some intermittent driveability problems for over a year now. Sometimes it cuts out while driving down the highway and sometimes it may go a month without doing it, then all the sudden do it for 3 days straight. I assumed the fuel pump was the problem and that it was on its way out, but rather than spend the money on a fuel pump I thought I would wait till it completely quit. Well lately it has been doing it, and sometimes the truck just falls on its face like its running out of gas. It usually does it when you first start it up, usually if you rev on it a bit it clears up and is fine till you shut it off and start it up again. I think it is a fuel pump issue but some other things have me second guessing that diagnosis. For 2 years now my battery and brake light has been on, I checked the voltage at the battery and it shows 14 volts as it should and the battery has never failed. However one day I was driving along and the amplifier on my stereo quit. Coincidentally the battery and brake light went off at the same time. Since then I have noticed that sometimes I will start the truck and the battery and brake light will stay off, the amplifier will not come on, and the lights are real bright. I checked the voltage at the battery and it shows 18 volts. I thought the battery/brakelight meant your alternator was over or under charging. Im my case the lights mean its working properly and lights off mean its overcharging. The reason the amp turns off is because it is going into overvoltage/protection. Could this problem be related to my fuel pump issue too? No sense in spending $100 on a fuel pump if it is an electrical issue, or killing a new pump because of an overcharging problem. What do yall think?

ksti

What year and motor 4 or 2 wheel drive?
Have you checked for any stored codes in the system?
Do you have a repair manual or a FSM?

Bill Edgar

It's a 1994 4wd 22re with a 5 speed. I did not check for codes because no check engine light so I assume it hasn't thrown a code. No I don't have an FSM these days I just use the internet.

ksti

Quite the contrary, a check engine light does have to illuminate to have code/s stored in the ECU. (computer)

Bill Edgar

So it can throw a code and not illuminate the check engine light?

scope103

Some codes are stored. When the code "goes away" the CEL goes off, but you'll have a record.

While your toughest problem is an intermittent electrical one, you clearly have an over-charging issue. 18v will kill your battery pretty quickly.

I've never heard of getting a "alt" light on over voltage. One side of the alt light is connected to B+, and the other side to the "alt" lead on the alternator. When the alternator is not running, "alt" is at ground. When it starts producing power, it comes up to B+ and the light goes out (B+ on both sides means no current). So having alt come up to 18v will still extinguish the alt light.

The over-voltage condition traces directly to the voltage regulator in the alternator; it has nothing to do with codes or fuel pumps or anything else. Your 18v measurement is enough for me to replace the alternator, but you can take it to just about any auto-parts store and they will check it for free.

Once you get that iffy alternator under control, you can address your other electrical issues.

Kolton5543

Its most likely your alternator heading out the door. To be sure though there is a wire connected to it that the alt uses for regulating voltage. If there is a loose or corroded connection in that wire the alt will raise the out put voltage until it finally sees roughly 14v at the alt. If theres no voltage at all the alt defaults to a set voltage, usually 13.8ish. The reasoning for this is there will be voltage drop through the electrical system. The sense wire comes from further down the electical system. If there is say 1.5 volts dropping through the system the alt will raise to 15.5 volts to maintain 14 volts where ever the sense wire comes from

So, what I'm getting at is you need to make sure the alt isn't over volting because of a different problem. it simple to test. Measure the voltage at both the alt charging post and the sense wire at the alt plug. If the readings are close then its the alt. If there's 18v at the charging post but only 14ish or less at the sense wire then you have a bad connection somewhere else in the electrical system.

As for your issues with the engine cutting out, it very well could be from overvoltage. You need to fix this problem first before further diagnoses. on things for sure. If you have to replace the alt, there is no better time than now than to swap to a GM cs130 or cs144. Id recommend the cs144. They are physically a little bit larger but put down 140 amps unmodded.

Bill Edgar

IfI were to pick up a cs144 alternator how would I go about it? Is there a make and model I would give to the Auto parts dude? I google searched them and it looks like an easy swap but I cant afford a $400 powermaster chrome plated alternator

RAD4Runner

Starting with basics, are all connections good? Do they all have bare, shiny metal, tightly contacting bare shiny metal?
Auto store should be able to check alternator as Scope says^^^, BUT you must ensure your connections are good.
Like Kolton says above, "S" terminal of alternator should read exact battery voltage. If "S" terminal connection to battery is bad "S" will not see proper voltage (13.5V to 15.1V) alt will attempt to put out higher voltage until it "sees" the right voltage, resulting in actual voltage at battery that is higher than normal. Check connection between that and battery. Measure voltage at "S" terminal and compare to voltage at battery post which should be between 13.5V and 15.1V with engine running.

Here's 22R-E charging system schematic and voltage readings to expect at various points:
https://www.yotatech.com/forums/f199...l#post52094780

Bill Edgar

Okay so I took my meter and checked everything on the alternator and here's what I got. I took out the Airbox and found the connector to the alternator underneath it. I checked for 12v on the red wire and good with igntion on. The white wire showed 14.37 volts and the battery showed like 14.31 with the engine running. Alright here is the crazyness, when I first started the truck it showed 14.4 and climbed to 16.98 on both the yellow sense wire and the white alt to battery wire. The lights on the dash stayed off, then after a few minutes the voltage on the thick white wire dropped to 14.4ish volts and the yellow sense wire to .69v and the brake and alt light came on. Do you think it is my alternator? Like I said I have never had any charging problems, just the lights on. Could it be just the regulator?

RAD4Runner

Good job with the voltage checks.
Yes, looks like it's a defective regulator. After the few minutes, it puts out proper charging voltage, but thinks it does not and yellow goes low.

"S" wire reading slightly higher than batt post voltage is to be expected because physically, the "S" wire is spliced on to the thick "B" wire before the "B" wire reaches the battery. Therefore, the "S" wire reads the voltage closer to the alt voltage. There is a slight drop on "B" wire from the splice to the battery post.

scope103

My EWD shows the Red is IG (to the Engine fuse), White is Sense (direct to the 40amp fuse), and yellow is the "L" or Alt. When L goes low, it illuminates the Alt light.

The White (sense) wire should be in lock-step with the voltage at the battery post (at least within 0.3 volts or so). If the sense wire is reaching 16.98, then you're getting something very close to that on the battery terminal, and that is definitely too high. (You're probably getting a little higher than that on the fat yellow "B" wire).

I suspect you've got a somewhat intermittent failure of the voltage regulator. Why it is lighting the Alt light only AFTER it's done the damage to the battery is a mystery to me. (The Alt light isn't designed to come on with OVER-charging, rather with significant under-charging.)

If I got those results, I'd be satisfied the problem is in the regulator and I'd replace it. But since the regulator alone costs about what a new (aftermarket) alternator does, I'd just swap the alternator. RockAuto has them for $85-$120.

A good idea would be to pull the alternator and take it to an auto parts store that advertises free testing. But keep in mind that you're seeing an intermittent issue (so it may not happen on the bench), and the reason the parts store does free testing is to sell you a new alternator. Getting one while you're standing there is better than waiting for 2-3 days to have one shipped, but first figure out HOW MUCH it will cost to have one shipped to you. Then you'll know whether it's worth it to buy one at the brick-and-mortar store.

RAD4Runner

+1 for just buying a whole alternator vs regulator.
I have found Toyota Parts Deal to have the best deals on OEM often:
https://www.toyotapartsdeal.com/part...lternator.html

O.P.,
One consideration IF you have a stock Toyota alternator, AND you foresee buying another Toyota alt in the future (brand-new or reman with Toyota warranty), the seller will honor only a Toyota alt for core refund.

Bill Edgar

Yeah I'm going to replace the alternator. I think I am going to swap in a GM 1 wire alternator and do the big 3 while I am at it. It looks like if I buy the bracket from LCE and a GM Alternator I can get more output in a simpler set up for less than the cost of a OEM Toyota alternator. There is a new 160 amp alternator on craigslist right now for $100. Any thoughts on this swap?

se7enine

iTrader: (2)

I've got an unused TG GM 1 wire bracket kit that I don't need. Can have it for $25 + shipping.

Kolton5543

Yeah looks like a bad regulator. I would stay away from the 1wire setup. They don't regulate as well and require a certain rpm before they even turn on and start charging. Besides all the wiring to make a normal cs series work is right there. Just go with a cs130 or cs144. They're cheap, reliable, make good power and are easy to install. Use one that has the mounting holes 180* from eachother on the case. The other style is doable but doesn't fit as well. Just look them up for a 95 caprice. Base model for a cs130 or tow package(b4u) or police package(9c1) for a cs144. To make them fit you just need a few washers for the top bolt and modify the adjuster till it fits. I dont remember what I used for a belt but I used the other mounting version. I think if you use the 180* mounts it could use the original belt but I could be wrong. Google it. Its a very common swap.