charging issue

[deadmonkey]

Swapped the engine from the '78 parts truck to '76 620 awhile back. I swapped out the '78 wiring harness into the '76 so I can ditch the points.

 

Had O'riely test the 5 month old Alternator and of course it checked out good

Had O'riely check the battery too and it good but little low on voltage at 12.3v but excellent cold cranking amps

Had O'riely check while it was all in the truck as well... and like I already know he's all "it isn't chargin"

(I'm all... no shit shurlock)

 

So before I start tearing into the harness to trace stuff here is what I know;

- the '78 is internaly regulated so there is no regulator to check, only relays

- the "S" field coil wire on the alt has 12v all the time regardless if the ignition is on or not ('78 is wired that way, '76 and '77 have a relay)

- checked power at ignition and there isn't a short; all is well at the ignition

- the service manual schematic (http://www.olddatsuns.com/620tech.htm) shows it wired up properly

- With lights on high beams (like the manual says) should be at least 12.5v at the battery, it is 11.5v regardless of RPMs

- I think I will start by tracing down the Bat wire from the alt to the bat.

- There was a voltage diff between + on battery to the bat wire on alt, but don't remember the dif, but there was one.

[ggzilla]

Should the S wire be hot all the time?

[ggzilla]

The internally regulated is a Hitachi LR.

It has a T-connector with S and L connectors (the old one has F and N)

[ggzilla]

1. Check the V at the alternator. Between the BAT terminal and the E terminal (earth/ground) there should be the same V as at the battery. If not, you got a wiring disconnect

 

2. The S terminal should be 12V hot all the time (as you said)

 

3. The L terminal (Lamp) should be:

* 0V when key is turned OFF

* 12V more or less when key is turnd ON

 

Because the L terminal is the exciter, if your CHG lamp is burned out, it won't charge.

[deadmonkey]

1. Check the V at the alternator. Between the BAT terminal and the E terminal (earth/ground) there should be the same V as at the battery. If not, you got a wiring disconnect

 

2. The S terminal should be 12V hot all the time (as you said)

 

3. The L terminal (Lamp) should be:

* 0V when key is turned OFF

* 12V more or less when key is turnd ON

 

Because the L terminal is the exciter, if your CHG lamp is burned out, it won't charge.

- CHG lamp is definately working... been lit since I put in the harness :)

- I'll check the 0v OFF/12v ON for the L terminal when I get home (at work now)

- the 'E' I'm checking is simply the ground on alt right... Not sure if my is labled E, but yeah. I'll check the voltage diff as well when I get home.

 

Fun fact, argued with the Shucks/O'reily guy about it, but according to the wiring diagrams, the '76 and '77 have a voltage relay and therefore do NOT have constant power at the "S" terminal. It is 0v until the key is turned on, then is 12v. At least this is how I read the schematics.

 

I always figured the "L" wire was just the stator ground. Guess I've never took the time to look :)

[ggzilla]

I read the diagram say way as you.

 

I always figured the "L" wire was just the stator ground. Guess I've never took the time to look :)

 

The L is the stator wiring nuetral point, which is why it is labeled N in the older alternators. When it is not outputting a charge, it is effectively ground hence the lamp comes on. When charging, it puts out voltage, so the lamp goes out (the other side of the lamp is 12V IGN).

[deadmonkey]

K,

 

across battery + - terminals = 12.27v

at Bat on alt = 12.27v

at "S" on alt = 12.27v

at "L" on alt = 0v with ignition off and = 11.97v with ignition in on position

 

So what gives... that all looks right

 

Just to make sure I wasn't going insane I disconnected the Bat wire from the alt and reads

13.5v at idle no load

20+v revved up no load

I sure hope it is supposed to get that high w/ out a load.

[ggzilla]

Swap a battery from your other car and see if it's OK. Even though they tested the battery, maybe it is not good?

[deadmonkey]

Swap a battery from your other car and see if it's OK. Even though they tested the battery, maybe it is not good?

yeah... That and putting the OLD alt from the parts truck in and test that too :poke:

[deadmonkey]

WTF folks... WTF.

 

Swapped with good battery; same

Got a BRAND NEW alternator and plopped that in; same thing.

 

What gets me is they tested the old alt and it was good. I told them it was putting out 30v with no load and they said it was bad, and to bring it in for a replacement. They tested it again and it tested bad!

 

SOoo...new alt, same issue.

 

I pulled the relays while the truck was at idle and they all click

I pulled the Auto-choke relay and all 4 wires are giving ground continuity with ignition off... is the correct?

 

I pulled all the blinker/headlight plugs and every other device including relays while checking the voltage output on the Bat wire and same.

[datzenmike]

I wouldn't run without a load, the battery prevents voltage spikes. Any transistor can be ruined by over voltage.

[deadmonkey]

I wouldn't run without a load, the battery prevents voltage spikes. Any transistor can be ruined by over voltage.

brand new alt...Have not done that with the new.

but the old wasn't producing any voltage with load (i.e. battery hooked up) and only with out the Bat connected.

[deadmonkey]

Sigh... guess I'll start pulling apart the wiring harness I guess.

[ggzilla]

I wouldn't pull apart the wiring harness.

 

The only thing that matters is this:

1. Battery to Alternator BAT terminal

2. Battery to Alternator E terminal (Earth/Ground)

3. 12V to the alternator S terminal

 

Clean all these connections, make sure they are tight, measure them with a voltmeter. And clean the battery terminals. We want to see bright shiny metal!

[deadmonkey]

(flashbacks of basic training)

Sir! Yes Sir!

[deadmonkey]

OMG Schucks/Oreily pissed me off today.

So I had a shop look at shit thinking the only thing left was something with the wiring. I was tired of hunting down gremlins and now have to pay for 2 hours of work. Turns out, nothing is wrong with my wiring, but Schucks keeps trying to give me an alt that is meant for 76/77 trucks that are externally regulated. At last I KNOW my wiring is perfect now :)

 

I tell them I need the internally regulated one, they give me one that doesn't fit, so they gave me the externally regulated one which obviously won't charge with out a regulator.

 

The one they are trying to sell me IS internally regulated and IS meant for the '78, but does not mount up because one mount hole is bigger and has a lip. The mount does not match. I tell them this and they tell me it is the right part! I tell them the truck is 76 (my first mistake) and the wiring and engine is 78. They try to tell me it is my fault it doesn't match now because I'm modding the truck. After trying to tell them the engine is the flipping same for nearly every year and they have the wrong part listed for that truck, they tell me there is not much they can do. So I'm at an impasse with them!

 

Fucks basically won't entertain the possibility that the part they are trying to sell me for the 78 is wrong and does not match up. If I bought it I would have to grind down the lip and press in a spacer OR drill out my engine mount to match the hole and lip! I know I could easily do either, but it is a matter of principle at this point.

 

Just for shits and giggles I went to Rockauto's site and looked at the pic that pops up...guess what, the mount looks right! imagine that.

 

NOW... I could be just going in circles because who ever had my parts truck before me COULD have put an earlier engine in it but I don't really think there is any diff between the 77 and 78 alt mounting brackets. If so, I'm the asshole, of not, they are!!

 

Either way, I'm pissed. I'm going to a parts place that specializes in metrics tomorrow to look at one they say is supposed to fit to make sure...core in hand. If so I will rub it in Schucks faces and be like look here bitches, here is the RIGHT part number.

 

sigh

/end rant :)

[I'm BLUE]

that really sucks man ! I have had that happen too many times that I just have a routine for buying some of this kind of stuff

 

ohhh and it's pronounced "schmucks" not "schucks" :lol: ;) ( I thought schuck's sucked before , now they are O'Reily auto parts ,,, I really wish they were schucks again :rofl:

 

240z Engine Gasket Set

 

O'reily Online (w/free shipping) = $79.00 ( 5 business days shipping )

O'reily Store = $145.00 ( 7-11 business days shipping , and to sweetin the deal they weren't sure if it come after that amount of time :rolleyes: )

[banzai510(hainz)]

I knew the wire harnnes wasnt bad!!!!! Unkess it has a amillion splices in there from the last onwer most times they are good at just at the ends may be bad.

So every time soembody say Im going to put in a Painless wire harness I cringe!!!!!!! WHY!!!!!!!!!!!

 

Datsun recharging systems are really simple!

 

remember the trucks used the samller Alternators(like L16 510 size) cause of the idler arm issue. the same year in a car will have a bigger size alternator 610/710/200sx. esp the later years

[deadmonkey]

Works perfectly now!

...and holy crap the Alt they gave me is Gargantuan. It barely fit into the space the space for the old one. I had to buy an inch longer belt and have no more room to tighten the belt up anymore, but it is good where it is as long as it doesn't start squealing...which I'm almost certain it won't.