Ka24de Alternator No Charge

[nostalgic_nissan]

So I have a 93 240sx that has been auto to 5spd swapped
was swapped by previous owners.

I’ve bought a brand new battery and alternator and my alternator is not charging my battery :/

I have double and triple checked all my wiring coming from the alt to the 75amp fuse to the battery and all the grounds with multimeter testing for continuity and voltage drops.

Have tested for 12v power with the ignition on to my gauge cluster cause I’ve heard the W/R wire from the alt plug goes to the battery light to tell the alternator to start charging but I’ve noticed my battery light doesn’t light up with the ignition on.

So I changed the bulb and tested the plugs going to the gauge cluster and it checks out for 12v with ignition on so I’m assuming it’s okay, but my battery light still doesn’t turn on after I’ve replaced the bulb several times.

I’m stumped :p any advice in what direction I should start looking to hunt this no charge problem down would be greatly appreciated

Cheers

[VStar650CL]

There should be a fused "field" wire in the alternator connector that needs to have 12V. If the fuse is blown or there's a wiring issue preventing that terminal from being powered, you'll get no output and sometimes no light (depending how the alternator's guts are configured).

[nostalgic_nissan]

I’ve tested the alt plug for 12v and it checks out and I’ve also tested the alternator diode and that also checks out.

I even pulled my alt out of the car and pulled the casing off to look at the rectifier and B terminal and it looks good.

But even when I just turn my key to the on position the battery light doesn’t even turn on, even with the cluster plug in receiving 12v

[VStar650CL]

The bulb signal and field signal will be separate wires. The bulb should be a White/Red wire on the "L" terminal. You should see a weak voltage on it through the bulb and the Bulb Check Relay coil (dim bulb using a test lamp), and disconnecting the wire from the alternator and grounding it should make the bulb light. If there's no voltage on it, the first thing to check is fuse #8 in the cabin fusebox. The alternator field terminal (S) and battery terminal (B) are both White wires and both fed through the Gray fusible link in the Fuse & Relay Box on the right front fender. If that link is popped you'll get a no-charge condition. Both White wires should show constant 12V with a test lamp. Lastly, the SX alternators had a separate body ground strap (E terminal) and may not work right without it. If you have a solid ground at E and solid 12V at S and B but the voltage on B doesn't rise with the car running, your new alternator is defective.

[PapaSmurf2k3]

Subscribing. Having a similar issue with a toyota I'm working on.

[VStar650CL]

Subscribing. Having a similar issue with a toyota I'm working on.

I can get you Toy info from Identifix if you want to tell me MY or VIN.

[PapaSmurf2k3]

1986 Pickup w/ 22RE... 4wd if that matters.
Put a new one on... the one I pulled off didn't look too terribly old. The new one lasted about a week or so and now I'm back to basically reading battery voltage throughout the vehicle (under 12v while driving).
It does have a slight power steering leak at the pump above the alternator. I'm wondering if its dripping down and gumming up the works.

[VStar650CL]

There are two versions, with and without a Charge Lamp Relay. Know which you have?

The only thing that makes old Toy alternators different from Nissan is an Ignition terminal for the logic supply in the regulator. You should see 12V on both the B and S terminals (White), if not check the 60 or 80A fusible link in Fuse & Relay Panel #2. The IG terminal (Red) should go hot with the key, if not check the 15A fuse in F&R Panel #1. The lamp is on the L terminal (Yellow) and has its own 7.5A fuse in F&R Panel #2. If all of that checks out but it won't charge, the alternator is dead.

Oil and fluid leaks usually take a long time to kill an alternator. So I'd say it's possible but unlikely that your P/S leak caused an issue in the course of 2 weeks.

[nostalgic_nissan]

Yeah I’m beginning to think that the local auto parts store sold me a defective alternator.

I have my cluster ripped out of the dash at the moment testing all the wiring to my check battery light that gets power but doesn’t turn on with the new bulb installed

Because It should turn on with the ignition in the on position but it doesn’t :/

My 75amp fuse isn’t blown either

B & S Terminal have voltage but don’t raise with change in engine RPM

[VStar650CL]

The IG terminal needs to have voltage too or I don't think you'll get output. If the charge indicator circuit inside the alternator is working then it should light a test lamp strung between Yellow and the battery+ terminal. If that lights then the charge lamp problem isn't in the alternator. On trucks with the relay, the Red wire on IG also drives the high side of the relay coil, the Yellow L wire drives the low side of the coil. So if IG doesn't have power then the lamp won't work either.

[nostalgic_nissan]

I’m just getting more and more lost and confused with all this electrical, I’ve literally ripped my dash out of my car. Everything is getting power but my cluster light for my battery and ebrake light don’t come on with the ignition on, my open door and seat belt light come on right beside it so it’s providing power to the plug

Don’t know if my cluster is pooched or my alternator.

Ready to take my car to the shop cause I’m just getting super frustrated at this point :p

[nostalgic_nissan]

I’ve checked my bulb check relay, have checked wiring from the alternator to the fuse box, fuse box to the battery, w/r wire to the cluster plug, have switched out all the bulbs in my cluster even swapped out clusters.

I’m literally lost, uggh……

[VStar650CL]

Are you using a test lamp, or just poking in the dark? If you use a lamp and do the steps I outlined, it won't be rocket science to locate the problem. It's a simple power circuit, and to test it you use a simple bulb that draws power.

[nostalgic_nissan]

I’m testing all my wiring with a MultiMeter not a test light.

I’m getting 12.3v to the ignition and the alternator, ive tested all my wiring in the circuit for voltage drops & continuity and nothing wrong is showing up

Going to take my alternator out again and take the stator & field/stator windings out n inspect

[VStar650CL]

VOM is the wrong tool for power circuits. If there's no current flowing then it doesn't show up resistance in the circuit. The lamp needs current and tells you dynamically whether the circuit is healthy. Harbor Freight, $4, and it's a decent quality piece:
https://www.harborfreight.com/612v-circ ... 63603.html

[nostalgic_nissan]

I put my alt in after cleaning it and it didn’t work
So I went digging through my old parts and found an oem alt that has been sitting for 5+ years, cleaned the stator and field windings n connections, put it in my car and BANG, it pumps out 14.2v when I full field it. So that is good

but he battery light still doesn’t turn on though when I turn the key into the on position :/

[VStar650CL]

Most likely a problem in the Red/White wire between the alternator and the cluster. The Bulb Check Relay just drives the Brake warning lamp anytime the alternator goes south, so if you're getting a Brake lamp but not a Charge lamp then the problem has to be in the Red/White wire which goes to both, but it tells you the break is between the cluster and the junction splice where the wires merge to go to the alternator. If both lamps are out, it tells you there's either a break in Red/White on the alternator side of the splice or the cluster has a problem. To determine which, put a test lamp between any handy 12V and the Red/White wire, either at the Bulb Check Relay or the back of the cluster (whichever is easier to get at). With the key-on-engine-off, if the test lamp lights, then the wire to the alternator and the alternator output are both good and the problem has to be in the cluster. If it doesn't light, Red/White is broken somewhere between the cluster and alternator or the alternator output isn't working. Repeating the same test on Red/White by back-probing the alternator connector will tell you which. If the test lamp lights at the alternator but not at the cluster or relay, it means Red/White is broken in between.

This is a perfect example of the deficiencies of a VOM for these sorts of checks. The VOM will read 0V whether the alternator bulb output is good or not, but it won't tell you whether the 0V means ground or open-circuit. The bulb will tell you that, because it can't light unless the alternator bulb output supplies a ground.

[nostalgic_nissan]

Yeah neither my brake or charge lamp light up with the ignition on, im leaning more towards my cluster being pooched because my speedometer doesn’t work either and I have to guess my speed based on rpm’s while I’m driving.

But I’ll pick up a test light tomorrow and start testing the wiring as you said

[PapaSmurf2k3]

Full brake lamp and charge lamp on my Toyota over here... along with AT oil light.

Everything on my end checked out OK. 12V at both white wires, and 12V at the red and yellow wire when key-on. New alternator going in today or tomorrow.
I have one of these handy power socket volt meters that I let the owner borrow previously when the alternator was starting to go out. Sometimes it was reading 13.8V while driving, and then it would cut down to just battery voltage. Told him to start making his way home if it cut out for any extended period of time. He evidently took that to mean he can continue to use the truck for a week or so on just battery power. It dropped to 8.6V and left him stranded.

[VStar650CL]

Sometimes it was reading 13.8V while driving, and then it would cut down to just battery voltage.

When they cut in and out like that, it almost always means the internal regulation is failing.

[PapaSmurf2k3]

Put the fresh one in last night and went for a decently long cruise while monitoring voltage. 13.2-14v seems to be where it wants to live. A little lower than I'm used to, but a hell of a lot better than 8.6 haha.
Thanks for the help guys. I had a feeling the alternator we had put in was a dud, but its always good to check everything else and get a 2nd set of eyes on it.

OH, the new one came in with a bent pulley too... had to swap that out with the old one.

[VStar650CL]

Put the fresh one in last night and went for a decently long cruise while monitoring voltage. 13.2-14v seems to be where it wants to live. A little lower than I'm used to, but a hell of a lot better than 8.6 haha.
Thanks for the help guys. I had a feeling the alternator we had put in was a dud, but its always good to check everything else and get a 2nd set of eyes on it.

You're most welcome as always, glad you got it straightened away. Pre-2000 alternators rarely regulate at a flat 14.2V like you see in modern stuff, simply because the silicon wasn't that good at load response. That voltage range is fine for an alternator of that time period.

OH, the new one came in with a bent pulley too... had to swap that out with the old one.

It's always something with remans, ain't it? Sheesh!