Wysmith95

Well, after browsing these forums for a few days now, I've decided to join and see if I can't get some help with an electrical problem.

I picked up my first Toyota a few days before Christmas. Love the truck, but all of a sudden I have a couple strange problems. Truck is an 89 4x4 with the 22RE 5 speed. I'll put a picture or two up later.

Anyway, I had the charge and brake light come on the dash driving home. Charge gauge showed maxed out. My uncle had me disconnect the battery while the truck was running to see if it would stay running. It ran rough and the wipers wouldn't turn off but it did run. He said this means the alternator should be fine, however I haven't ruled it out. I replaced the battery next and after that the headlights quit working. I have tail and dash lights just no headlights. I had very dim high beams for a while and those quit as well. Now I don't even get the indicator on the dash. Any suggestions on where to start? My grounds all appear to be OK, I am going to check them again in better light today. I've been reading around these forums and I haven't found anything directly related to what I have going on. Any help is appreciated, thanks everyone!

KBAM

Time the break our the volt meter! See if you have any power at the plug on your headlights (passenger side). Check fuses, the usual suspects.

Side note for after you find the culprit- You might consider upgrading the headlight harness if you are losing voltage at the plug. The stock harness on my 91 was junk. A $30 harness and new H4 lights off ebay, I had bright headlights again with no voltage loss.

Edit- Thought I should clarify on the side note above. By "losing voltage", I mean less than 12v, not 0v. If you have 0v you have no power at all and you should fix that issue first. Then determine if you should consider further action.

Odin

Don't run the engine without the battery hooked up, that's a good way of shortening the life of the alternator and in some cases it can take out the ECM.

Stop replacing things until you find out what's wrong. If you still have it immediately try charging your old battery back up to full strength on a good charger.

Don't just assume your power and ground wires are good and making strong contact. This assumption has cost a lot of people some good money. The cables on these trucks are pitifully small and it doesn't take much corrosion to effect them. Get out a wire brush and clean all the ends of the connectors and the areas they are connected to. Scrub them with a wire brush or some 0000 Super Fine steel wool, it's easy and won't take that long.

If you still have problems it's time to do a voltage drop test to look for bad connections, bad wires and check out your alternator. It's very easy to do. Electronical stuff confuses me but even a simpleton like myself can do it. Start by watching this video then watch some different ones if it still isn't clear.

Wysmith95

I feel a bit stupid after this one. Apparently I had that rare coincidence where both high and both low beams burned at once. Replaced headlights, lights work. Connectors will be replaced in the news future just because they are in rough shape.

Still have my charge light and brake light on inside, batt gauge still on 18, I'll have to see if the battery dies overnight tonight. Is this still seeming like an alternator?

Edit: Sorry didn't see the above post until after I put this up I'll watch those videos.

Schnayke

iTrader: (1)

My last 83 had a charge and battery light come on randomly during a bump but it was a false reading. I had plenty of charge and the brakes where fine. I didn't figure it out but it wasn't any of the parts it was warning me about. Put 100's of miles in a single day with it on with no problem. did it off and on the whole time I had the truck. I had planed to remove the dash and replace it and the wiring harness, but never got around too that. So I also never got around to figuring out what the issue is.

wyoming9

iTrader: (1)

Hello your voltage regulator which is in the alternator is Kaput!!

Take your Meter and measure !!

The head lights popped because they don`t like the 18 volts

The charge and brake light come in both a under or over charge condition yours is a over charge

Like Odin said never disconnect the battery while it is under load.Engine running if this arced no telling what circuit protection may have opened.

One could get away with this back in my misguided youth before computer controlled engines let us hope you did not fry anything else.

Odin

^^^ Sounds like a winner to me!

18v - Don't start that thing again till you get the alternator replaced or it'll cook your new battery too. Not to mention it's not the best thing for the wires either.

Wysmith95

Ok, tested alternator, I put out about 17 volts according to volt meter. Voltage regulator was my hunch after that. Luckily we have another pickup of the same year as a parts truck as I'm short on cash currently. Will be changing the alternator and see what happens.

Didn't know you weren't supposed to disconnect battery while it was running. We didn't leave it like that, his test was just to see if the truck died when it was unplugged. Hopefully a couple seconds of that didn't mess anything up.

Marc

That was a valid test way back when vehicles used generators.
Not good with alternators.

RJR

A "couple of seconds" is lifetime (literally) when it comes to blowing up electronics. Usually an overvoltage surge will take out unprotected transistors and IC's in a matter of milli-seconds - much faster than a human can react. There is no "safe" time for an overvoltage event.

That being said, the auto manufacturers recognize that voltage regulators fail, and are pretty good about building protection into the ECU's and other more expensive electronic parts. Your aftermarket stereo, maybe, maybe not.

Disconnecting the battery is NOT the best way to find out if your alternator is working, your uncle notwithstanding. The best way is with your trusty multimeter. With the engine running, voltage at the battery should be between 12.5 and 13.5, 14 absolute max. Lower means your alternator likely isn't working, higher means your voltage regulator is not working.