Thread: Charging system failure.

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In answer to your other question, why are there three wires coming out of the Toyota alternator connector? Two of the wires (one is field out, one is stator out) on the Toyota alternator are on the inside of your internally regulated Delco alternator.

Wait a minute...

There are four (4) (IV) wires coming out of this alternator!

The big stud => Stator?
A green wire => Which is the field (fer sure)
A Blue wire => ??
A Black wire => ??


Care to comment on the ??s?

Okay there does appear to be NO charge light relay in this vehicle only a choke heater relay.

YES! the charge light was burnt out!
It's one of those twist into the circuit board lamps. I pulled it and the brake bulb next to it. They are both the same bulbs.

I exchanged the brake bulb for the burnt out charge bulb and..... no difference.

I got to wondering about the wiring back to the bulb. The bulb has 12V applied to it when the ignition is turned on. So with regulator removed I grounded the yel/white wire that goes from the regulator to the charge lamp thru another 12V bulb. They both came on about 1/4 brite, about what I would expect. For the bulb to light normally the regulator has to bring that wire down from 12V some, to get a voltage difference across that bulb and make it glow.

With the key on and the regulator hooked up I get 12V on that wire at the regulator which means the regulator is acting like it is open on that wire.

Time to investigate. I opened up the regulator dug it out of the silicon goo. There is a big power resistor laying on top. It measured 18.6 Ohms. The label sez 10% 19 Ohms which means it is fine.
There is a big diode that connects to that resistor (series) it tests fine too.

I pulled the little hatch from on top of the thick film circuitry board inside.

There is a thick film board with 2 Integrated circuits directly bonded to it.

There was a large blob of solder sitting on the clear silicon gel pool that the thick film board is under. I removed it with tweezers thinking, "this must be it!" Then I inspected the entire thick film board and ICs with a high power microscope. I could see no sign of any toasted little traces or IC traces or component failures. The big solder blob didn't look like it had penetrated the gel...

I reassembled everything plugged it in and..... the charge light doesn't come on with the key, and the alternator doesn't charge...

The ???
Big stud: stator out to batt
Green wire: field in from reg
One of the black or blue is the field out, I'm not sure which. It should come on with the key. (I would guess its the black)
The other comes from the stator, this tells the regulator what's generating so it knows whether to turn off/on the field. This one won't put out till the alt is turning.

Disconnect the plug at the regulator, turn the ignition on then ground that Yel/wht wire coming from the bulb, does it light then? If so, then you know that circuit is OK. What the regulator should be doing is taking that 12v, running it through the field (green)and back to the regulator to ground. (blue or black) If you're not getting a good ground this can't happen. Then check your block and body grounds. Physically remove them and make sure you've got clean metal to metal contact.

Why not stick in the delco and eliminate all that other stuff?

I worked for toyota for 15 yrs ,I always had a hell of a time with the old alts on pre 84 trucks ,once I had one that I messed with for days and found that toyota has 2 alts about the same ,take a real close look at the 3 wire connector on the alt is it exactly the same ,the one I had was a little different it would plug in but it was hard to do just something I ran into ,also I have had a lot of crappy aftermarket regulators

Originally posted by califgrrrl
If the light isn't coming on ever, I would change it. The idiot light has to be working because this is what 'primes' the alternator to begin charging. When the ignition is turned on voltage flows through the light, through the regulator to the field wire on the alternator.

wow that what i was thinking. califgrrl you are so cool
on some of alternator your can jump the two wires with a resistor or a delco one wire alt the older mopar alt work good to with the one wire regulator

Originally posted by califgrrrl

The ???
Big stud: stator out to batt
Green wire: field in from reg
One of the black or blue is the field out, I'm not sure which. It should come on with the key. (I would guess its the black)
The other comes from the stator, this tells the regulator what's generating so it knows whether to turn off/on the field. This one won't put out till the alt is turning.

Disconnect the plug at the regulator, turn the ignition on then ground that Yel/wht wire coming from the bulb, does it light then? If so, then you know that circuit is OK. What the regulator should be doing is taking that 12v, running it through the field (green)and back to the regulator to ground. (blue or black) If you're not getting a good ground this can't happen. Then check your block and body grounds. Physically remove them and make sure you've got clean metal to metal contact.

O.K. Caligrrrl, your a little too smart for the average home mech. and specially for a gurl,whats the story,very rare breed indeed......

Something Caligrrl hit on,I just looked at the 1983 diagram and that black wire runs from the regulator to the alternator and has to be grounded ,check and make sure it is grounded,seems to me it should ground at the lower alternator mounting bolt,but in any case it positively hasta make ground........

The Black wire is indeed grounded on the alternator. It is one of the little scrawny "three wires in the connector" The actual return current is left to the alternator mount and frame bonding which was inspected and found to be good, if not lamely designed. They ground the negative of the battery to the fender then bond the lower part of the fender to the suspension and the suspension to the engine block... Lame or what? The battery ground should ALWAYS be grounded with a stout Starter Current sized cable and the chassis and suspension (?) grounded from the block or directly from the battery too.


Boy you would think that black ringed stud would be negative if the red ringed one is positive BUT! in this case it is ALSO positive!

There is another big stud down lower that has a condenser body screwed to it and the positive condenser lead goes to the indicated black ringed stud.

Okay here is where we are now.

After hours at Google and at the car parts online stores I have discovered something not EVER mentioned in the Toyota manuals...

The Toyota nitwits put both A-Type and B-Type alternators into those Toyotas.

To refresh you.. The A-Type alternators, like ALL Delcos, have the field internally connected to the DC+ output. To control the alternator's output the regulator grounds the Field terminal varying amounts... More grounded more output. This is why on Delcos you can stick a paperclip into that little D slot and force the alternator to full output. (by essentially shorting the field terminal to the case)

B-Type alternators have the field wire GROUNDED inside the alternator and hence the regulator feeds more VOLTAGE to the field terminal to produce more output.

Obviously I have B-Type alternator because if I feed 12V to the field terminal I get maximum output.

Now if you've been following this thread you will know that my regulator seems to have all the correct signals going into to it but obstinately continues to send a big ZERO out to the field terminal!

My regulator is an A-Type regulator!!!

I figured this out because if you go to say..., Kragen Auto parts on the web and hunt down Alternators and Regulators for this Toyota you see umpteen references to 5-Wire and 6-Wire regulators. You also see reference to "B" type alternators.

Further searching finally turned up an application note at a car parts store that explained; Beware there are two types of alternators and regulators used in Toyotas. The alternator type must match the regulator type!!

If the wiring harness has six pins in the regulator connector then the vehicle was made as a B-Type. If the harness plug has five pins then the vehicle is an A-Type. [note: the plugs accept either they just depopulate one pin {the jerks}]

Well my harness has six pins... B-Type.
My alternator, via my test demonstrated it is a B-Type.
My regulator has five pins... A-Type.

This is why I'm getting nada...

How did this come about? Remember I just acquired this vehicle from someone who had replaced the alternator and regulator. {I never had a chance....}

Furthermore... If you go to the store and get the typical car-parts-jockey and he puts in your year Toyota he gets 15 alternators on his screen they are listed in order of cost, cheapest first. The B-Alternators are the cheapest. He-goes-to-the-refrigerator-and-gets-the-box... and hands you the B-Type alternator. Then when he looks up the regulator THE A-Type REGULATORS ARE THE CHEAPEST AND THEY COME UP AT THE TOP OF THE LIST. Again he assumes you want the cheapest... and hands you the A-type regulator... The die is cast..... This is what happened to me when I first discovered I must have a regulator problem, I went to the local Kragen's and asked for a regulator for that vehicle. I was handed one. No mention that there might be different types or that different types are available, "do you have a preference mister?"

Turns out I was summarily handed the cheapest one on the list an A-Type.

So anyway this is where I'm at. Later today I will exchange the Wrong Regulator with a Correct Regulator and see what happens.

I will report back!

Originally posted by DennyW
yep.
HWORRELL , can you post or send me a copy of the wiring ? I can mark it up for him.

Sorry Denny wasn't ignoring ya,had just popped into the shop to do some bookwork when I was posting earlier and left before your request,just now took a break from the coupe and am on the kids puter,sounds like he's got it figured out now anyway. Ya know I started to ask him if he had the right alt.last night because on the wire diagram it showed 1 with internal reg.,1 with mechanical reg. and 1 with electronic reg.....

Well we are stalled Ladies and Gentlemen..

Soonest I can have a 6pin B-Type regulator is Monday 10AM. So we wait...

Waiting is over...

Went in to the parts shop after being called and told the regulator was in... Got there and was handed another 5 pin regulator..The idiots!

So after much grumbling they looked up their local stock and found a '79" six pin in stock!

Well it worked perfectly. So that confirms the wrong regulator in the first place theory. Sheesh.

Thanks for all the help people and giving me ideas to check out.



Now on to the leaky exhaust manifold. I have never seen an exhaust manifold with no gaskets before.... Toyota R20...

don't know about Toyota, but i never use exhaust gaskets on SBC stock manifolds. works better with no gaskets for me.