Charging troubles

[aye mate]

Ok I had a thread that is now lost in obscurity and doesn't really match my current problem anyway.

As some of you know I have a problem with my charging system, meaning, it doesn't work. The battery is not receiving any charge from the alternator. I have used several different alternators that have been tested after I used them and they are in working order. I have replaced all fuses and some of the wiring that needed it. The battery is only a few months old and is able to charge up to 14 volts from a battery charger. I have continuity in all wires that run to/from the alternator to their respective locations whether it be the fuse box or battery.

Any thoughts?

 

[Shawndude]

With the engine running, what is the voltage at the alternator output terminal? What is it at the battery terminals?

 

[aye mate]

With the positive tester on the Alt. ouput and the negative tester on the Neg. batt. terminal the voltage is roughly the same as when the testers are on both batt. terminals. Around 12v.

On a side note; when me and my dad were fiddling around with it tonight, he tried to start the car. Not out of the ordinary because the car started and would run just fine off the battery. But this time he cranked it and I saw a small spark off the positive batt. terminal and now the car will not even crank. All the dash and head lights come on but the car will not crank. We did hear a clicking from the "main" relay in the fuse box in the engine bay. I took it out and tested it with an Ohm meter and there is conituity between terminals 1 and 2 but none between 3 and 4.

 

[Shawndude]

A spark at the battery terminal can only mean one thing. You have a loose or majorly corroded wire there, otherwise it wouldn't spark. Need to fix that up.

With engine running you have to see about 14V at the alternator, otherwise it's not charging. When you turn the key on, does the alternator light on the dash go on? When you start it, does it go off? The alternator will only charge by being provided power first, through that indicator light circuit.

A relay should show some resistance between 2 terminals (the coil) and none between the other two. Once you apply voltage across the coil, it will switch and then there will be continuity on the terminals that were open before. The coil should be something around 150 ohms or so.

 

[Joel W.]

I agree with shawn, On my car i have a seperate wire on the positive battery terminal that feeds power to the part of the ignition system, That wire corroded up on mine and would not energize the alternator.

 

[jetjock]

What Shawndude said. Any time you suspect a bad battery connection you can use the old trick of turning on the headlights and then cranking the engine. If the ligits go out the connection is bad, if they dim the connection is good but the battery is dischaged.

Shawndude is also right on about checking for charging voltage. Run the car at 1000 rpm with no electrical loads (lights, blower, ect) and measure across the battery. You should get around 13.8-14 volts. If you read battery voltage the charging system isn't working.

The alternator field needs to be excited for the alternator to work. This is the function of the voltage regulator. It senses alternator output, compares it to an internal 14 volt reference, and then supplys power to the field. By adjusting the current flowing through the field windings it keep the alternators output constant. It's just another closed loop on the car.

Since you have seem to have zero charging output and since you've replaced the thing a few times it appears to be a wiring problem. You should have power between ground and all three wires on the small connector. If not check the 40 amp fusible link, the 7.5 amp IGN fuse, the 7.5 amp Charge fuse, and the 15 amp Engine fuse and the wiring associated with them to the alternator.

Does the charge indicator on the dash light when this happens? It should. If not find out why as that could be your problem. I haven't checked on the Supra but on many cars the indicator is part of the regulation circuit and when the lamp fails you'll get no alternator output.

 

[Shawndude]

I haven't checked on the Supra but on many cars the indicator is part of the regulation circuit and when the lamp fails you'll get no alternator output.

Yes, same on the Supra.

By the way, I really enjoy reading your posts Jetcock. You put a lot of information and effort into it. Much appreciated. :love:

 

[Joel W.]

Psstt...It's Jetjock...lol and i agree again..

 

[jetjock]

Thanx for confiming that as I wasn't sure but it's a very common setup. I'm willing to bet that may be his problem since he seems to have exhausted everything else.

I've been reading your stuff too and darned if you don't come across as a guy who actually knows what he's talking about. Can't find a single error in any of your posts. Also nice to have another electrically savvy guy around. I've pretty much given up responding to electrical problems as those who understand it don't need the help and those who don't often can't figure out how to use it. I think I'll leave them all to you

Lol...Joel

 

[aye mate]

ummmm. thanks for all the info guys, I'm sure it will do someone else some good. Today my dad hooked up the negative batt. terminal(we disconnected it after we stopped working on it last night) after he hooked it back up the alarm started going off and he got inside and put the key in the ignition, the alarm went off and he tried to crank it. Fired right up. Then he checked the voltage at the batt. and at the alt... 14.5 volts. Freakin weird. So I am going to check a few grounds and drive it a little bit for a few days to see how it goes.

Also JetJock, my friends dad is a mechanic and suggested checking the failure lamp in the dash for the same reason you said. The way I did this was I put the OE Alt. back on(the one that was on when the Batt. and Brake light came on originally.) and it lit up with the ign. on.

Does anyone think that the alarm system might have something to do with this? A few weeks before all this started happening my alarm kept going off for no reason. So I jumpered the hood latch connection to fool the alarm system into thinking that a door was open all the time so that it wouldn't arm. The connection is still jumpered and everything appears to be fine.
Key Word- Appears. Thanks.

 

[jetjock]

Definitely sounds like a wiring issue. You could've verified the failure lamp by checking for power between ground and the three pin alt connector or shorting the lamp's terminal on that connector directly to to ground or thru a test light. (For electrical noobs I always suggest using a test light or fused jumper as it limits current should they make a mistake).

It's normal for the factory alarm to trigger if the battery is disconnected and then reconnected but otherwise it should have no bearing on charging system operation as there isn't (shouldn't be) any electrical connection between the two. You've got a gremlin somewhere though. Let us know if you find it because the charging system isn't all that complicated and since it sounds like you went through everything I for one am curious.

Here's hoping your battery didn't get too much of a workout as they don't tolerate abuse well. Even a single deep discharge below 10 volts cuts into their service life. Yep, check all the grounds. Grounding is more important than some people think, especially engine grounding. I once read a post where some guys advocated leaving off that small ground strap at the right rear of the engine to the firewall thinking it did squat. It's actually one of the most important on the car.

 

[aye mate]

OH heres something I forgot about! We were checking the fuses in the drivers side kick panel and noticed a 15amp fuse was MISSING. According to the Haynes diagram that particular fuse position is labeled "engine." It was AFTER we put that fuse in that the batt. spark(that was a loose connection as was mentioned earlier) and the car wouldn't start. After that happend I was able to hear the Main relay in the bay's fuse box clicking and we could hear a clicking in the kick panel box also. Thats when we gave up for the night. Then this afternoon is when my dad hooked the battery up and it not only started, but also started charging again. I am guessing the 15amp "Engine" fuse has something to do here. I'm not sure if there was a wiring diagram that showed what exactly that fuse is for.

 

[IJ.]

Have you checked the ALT LIGHT Globe yet?

(didn't even think of that as it's so old school I didn't expect that a modern car would still do it if blown)

 

[aye mate]

Definitely sounds like a wiring issue. You could've verified the failure lamp by checking for power between ground and the three pin alt connector

I did this with a volt meter and with the car on. I got 12 volts through 2 of em and 1 volt through the IGN one.
Also, with that fuse installed now the batt. light comes on when I start the car up but goes off, like the CEL does and is supposed to do. It did not come on and go off before.

 

[jetjock]

I'll quote myself from an earlier post: "If not check the 40 amp fusible link, the 7.5 amp IGN fuse, the 7.5 amp Charge fuse, and the 15 amp Engine fuse."

The 15 amp Engine fuse supplies the power feed to the voltage regulator inside the alternator. Without it the charging system can't possibly function. It's the ING terminal you got 1 volt on. As per my previous post you should've had 12 volts on all three ternimals.

You really ought to throw that Haynes book in the trash and get a Toyo manual. The EWD is nice to have too.

 

[aye mate]

^You're right.

 

[jetjock]

Stuff happens but the story behind the story is how'd the fuse go missing?

 

[aye mate]

Good question. Its right next to the wiper fuse which is a 20amp. Turns out the 15amp fuse was in the 20amps spot. So the real question is what happend to the 20amp wiper fuse and why did the 15amp engine fuse get put in its place? Most likely it was probably me, I have owned the car for almost 4 years and at one time or another I was probably screwing around down there and just mixed em up by accident.

 

[PorterzSupra]

*** The solution is VERY easy.. get a 160 AMP 1 wire GM alt, they go for about 130 bucks on ebay. All you do is hook ONE wire to the positive terminal on batt then forget it!! stock is around 60 amps you can get anywhere from 160-200!! Oh make sure you specify serpintine pully and u need to shim the pulley with 2 large washers so the belts line up perfectly. This is an amazing upgrade esp if u have electric fans and such let me know if u need more info, I am extreamly happy with mine, the reason I got mine is because the idle use to die down when my electric fan came on, now I can run anything I want. There are a few companys that modify GM alt to put out 160+ amps ***

 

[jetjock]

I won't bore you with the technical details but one wire alternators are bad news for several reasons. Extra capacity is always good but one wire control is not. With all the bastardizing I see done here it's no wonder some have so many problems with these cars.