SJ Alternator woes (Strange problem)

[binge]

Having a bit of a head scratcher here. Hopefully somebody can clear this up for me before I fork out on a new unit.

Truck was running fine. Went off road Sunday, ended up bonnet deep in muddy water. Dragged truck out, wouldn't fire on starter, tow started it, and drove it home.

All the way home, the battery light was coming on at lower revs. Not sure what RPM as I don't have a rev-counter. But I'd say it was anything below 1/2 maximum revs, whatever that is, the light would come on.

So I instantly assumed it was the alternator on it's way out.

Got home, parked SJ up. Went out this morning, and it fired up after a few goes, very reluctant though, starter motor was jamming up.

After work, it wouldn't go at all, but went on a push start.

This time around, there was no warning light on the dash at all. Not when it's on 2'nd stage ignition, and not when it was running either.

Managed to get it to my garage. I stripped the Starter Motor, cleaned it all up inside as it had all corroded inside. Works fine now.
Then started the thing up, whacked the multi-metre on the battery... 12.4v constant. No charge, no fluctuation of voltage.
Removed the main alternator terminal, and tested the alternators output. It was giving under 2 volts.

So I whipped it off, stuck another alternator on I have spare. Which I was sure worked before I removed it from the 410 engine.

Exactly the same. No warning light at all, and no charge from the alternator.



Now I started to investigate, and I am not sure if the following is normal.

Ignition off:
Red/White wire - 0v
Black/White wire - 0v


Ignition on:
Red/White wire - 12v
Black/White wire - 12v

When I give the red/white wire a negative with the power probe. Dash warning (battery light) comes on.

Once the engine is running. Both red/white, and Black/white wires stay at a constant 12v, and when I whack a negative down the red/white wire, the battery light comes on again.


Terminals on the alternator, what I can gather, is top one is a dummy, one closest to engine is for battery warning light, and one furthers from engine is switched live?

If so, then the switched live one does nothing. The power probe doesn't register it as a live, or an earth at any time. So is this saying that both alternators are knackered?



Any help much appreciated.

IF, the alternators are both dead, then I will probably go over to a bigger one. What do people use?

[binge]

Anyone?

What about anyone with a working alternator in Kent I can borrow to test on my truck?

Or someone willing to test mine on their truck?


Or just a good method to test my alternator, as I don't know what readings to expect from the two pins in the plug.

[dan_2k_uk]

Despite being an electrician alternators are something I'm not too hot on.

If it has a removable brush assembly I would remove them and clean them up and try clean inside too.

[Darrell]

Now I started to investigate, and I am not sure if the following is normal.

Ignition off:
Red/White wire - 0v yes
Black/White wire - 0v yes


Ignition on:
Red/White wire - 12v yes, if tested disconnected from the alternator, or with engine running
Black/White wire - 12v yes

When I give the red/white wire a negative with the power probe. Dash warning (battery light) comes on. Yes

Once the engine is running. Both red/white, and Black/white wires stay at a constant 12v, and when I whack a negative down the red/white wire, the battery light comes on again. Sounds correct


Terminals on the alternator, what I can gather, is top one is a dummy, one closest to engine is for battery warning light, and one furthers from engine is switched live?

If so, then the switched live one does nothing. Not sure what your testing here, if it's the alternator terminal with the plug disconnected it will register 0v and the probe may not register it as earth because of the windings resistance. The power probe doesn't register it as a live, or an earth at any time. So is this saying that both alternators are knackered?



Any help much appreciated.

IF, the alternators are both dead, then I will probably go over to a bigger one. What do people use?

[Darrell]

I expect it needs a strip and clean or just hose the bugger with the engine running.
The brushes have probably stuck after running it in muddy water.

http://www.offroadingpics.co.uk/apps/ph ... =195369785

[binge]

Wicked. reading the above, it seems like I've got a dead alternator then.

The one that got ran up in mud is KO'd. I tried splitting it and lost my temper with it. haha! It's dead!

But my spare one doesn't work either. Will give it a clean out with some contact spray and see what is what.

[binge]

Had a Peugeot/Citroen alternator in my garage, which I was certain worked, as it came off a working van which was broken for parts.
I ran an ohms test on it, and it gave the right results (only gives resistance/a reading one way across the terminals).

Fitted it up (Had to modify the brackets on the engine), and surprise surprise. It's not charging!


So now I need a standard Alternator bracket. And just going to buy a brand new, standard SJ413 alternator. Cant be arsed pissing around anymore.

[Ladaman]

Do you have an auto electrician place close to you? They often spin them up and tell you if they are okay or not free of charge.

It might not be the alternator. Three duff ones?

[Darrell]

Do you have an auto electrician place close to you? They often spin them up and tell you if they are okay or not free of charge.

It might not be the alternator. Three duff ones?

3 duff ones sounds very unlikely. The wiring seems OK by the above posts unless I missed something.
I'm assuming the engine earth is OK or it wouldn't start.

Can't think what else, all it needs is a 12v supply down the black/white and being spun up..

[binge]

I've even tried bench testing it with a drill.
Tried giving it an earth with a jump lead.
Tried powering up the black/white terminal with a power probe.

It's really fvcking me off! haha!