MSilk

iTrader: (1)

Something I have noticed with this board is the issues seem to come in waves lol. Looking through the new posts it looks like there is a run on alternator problems and now I am in search of some help too.
So on to the issues at hand...

Car has been sitting for a few years with little work done on her, I now have some time to focus on getting her up to speed and have hit a couple bumps.
93 JDM, recently rebuilt alternator.

Started by watching the Commander and noticed voltage was at 15.9v, grabbed my DMM and checked at the battery 15.8v. I shut the car down and checked wiring to make sure nothing was shorted or loose ect. Everything checked out fine, started her back up 14.5v - 14.8v at the battery same with PFC. Took a quick drive all was good, next time I fired it up though 15.9v. I did the same thing with shutting it down ect but now I have no charging at all.
Somethings I have noticed:
Dash LCD seems to get bright and dim in waves (I am sure that has to do with the 16v)
I have no charging system fault lamp in the dash which leads to my first question. If that bulb is burnt out the L terminal from the alternator would have no load on it, will that stop the alternator from charging? (IMG1) Looking at the diagram it appears that way but want to make sure. Does anyone have any idea where the L wire goes from the alternator into the cabin? I would like to trace the wire and do a resistance test and a voltage drop test.

I also found a diagram where it shows the high exhaust temp wire tapped into the same wire as the ABS control unit which ties into the Alternator. (IMG2) Seeing as I have a RHD and the exhaust temp probe is outside of the cabin it has been damaged, looks like the previous owner in Japan let it drag on the ground and tucked it up above the tunnel heat shield. Does this sensor tie into the alternator at all or am I reading the diagram wrong?

IMG 1

IMG 2 FSM
Thanks

armans

iTrader: (2)

Don't remember the wiring details on top off my head. But to me it sounds like there is a voltage regulator issue in the alternator. Why not to take it back to the alternator shop and ask them to check it.

MSilk

iTrader: (1)

Already have, alternator checks out or so I am told. I was told to double check the field wires.

Thanks

Brodie121

iTrader: (8)

Definitely sounds like the regulator, what part of BC? I have spares if you're close and want to try one. I'm in the kootenays.

MSilk

iTrader: (1)

West of Prince George lol, thank you for the offer though Brodie. I am going to pull the cluster and check the light, try to find the diode and test it, as well as remove the temp sensor from under the car. I have a sneaking suspicion that temp sensor has a big part to do with my electrical gremlins. If everything is still pointing to the alt then time to upgrade with one of IRP's

The more I look at the second diagram makes me think it has to be the burnt out bulb for the no charge as the L terminal would be floating and not going high unless I am missing something...which knowing me I probably am lol.

I will post back with what I find.

Mike

Brodie121

iTrader: (8)

Brodie121

iTrader: (8)

Yes,it does excite the field, but it's not the only source. It's redundant (above diagram) It's just using the heat light/coolant light/oil light as redundancy and resistance as it needs some to function properly. If just the charge light is burnt out it should still work. I have the same dangling heat sensor on my car. You cannot just hook the field/bulb wire up to 12 volts, itll destroy stuff.

16 volts can only be a failed regulator unless you have an issue with the sense wire, have you checked what voltage you have on the S(sense) terminal and L terminal? I'm aware it's not charging at all now.

MSilk

iTrader: (1)

So I pulled the cluster and tested every bulb and they all work. I tested the diode between the alt and charge bulb and it’s good as well. Pulled the plug off the alternator and noticed damage down where the plug pigtail goes into the harness so I investigated and low and behold both the S and L wires insulation was cracked and it looks as if they were touching. That could explain the 16v. After de-pinning the plug and re wiring it I tested continuity back to the dash and it’s good. Still no charge out of the alternator but I would say the S and L wires shorted together took the regulator out.
Diode specced out at .513
Resistance from dash to alternator was 1.8 ohms (I had a jumper running back to the alternator out the door)
S terminal with car running 12.05v
L terminal with car running 12.35v
B terminal with car running 12.35v
Battery 12.35v while running
Still no charge light illuminating though which I find strange.

So all said and done I think it’s time for a new alternator and try to figure out why the charge lamp is not illuminating.
Any ideas? Does your charge lamp light up Brodie?

Thanks
Mike

Brodie121

iTrader: (8)

Yes, my charge lamp lights up while cranking and until the engine comes up to idle.
Those 2 wires arcing will for sure take out the regulator,but electrically im not completely sure why.
It's something to do with the Sense wire needing the resistance from the bulbs. A lot of other systems just use a resistor to accomplish the same thing.
The charge light is a bit strange, its fed 12v normally, when alternator isn't making power you have 12v differential across it, when alternator is making power you have 12v at alt and 12v fed from bulb so no differential and bulb doesn't light.
But it's from the reg, so depending on failure mode of the regulator diodes you won't always get a light. I've had regulators go where i got an intermittent light for about 10 seconds, then stayed out until the battery died half an hour later.