Alternator light(s) but no other symptoms?

sk66

sk66

Moderator
Staff member
Went on an off-grid trip last couple of weeks and intermittently the alternator warning lights would come on (batt, water separator, A/T temp). Sometimes it would be very dim, sometimes brighter; seldom for more than a few seconds and never as long as a minute. At all times voltage was fine (varying between 13.8 and 14.4, typically 14.3-14.4 at highway speeds) and the battery remains charged.

I checked battery connections and wires... didn't find anything obvious, but reseated/tightened the terminal clamps anyway. I was in the woods, so I didn't really get a good look at the alternator side of things. Of course, the lights won't just stay on so I can troubleshoot, or even just test the alternator.

I was a little concerned about over-charging/over-heating as I expected the float charge to be around 13.5v. But I guess the alternator is not as smart as I thought and I've just never paid that much attention to the voltage output before... I think anything under 15v should be ok for the battery.

At this point my best guess is that the voltage regulator is getting ready to go out with a weird failure of the L terminal switching. I don't really think it's wiring/short related as all of the driving over rough forest roads had no effect... it also does not seem to be speed/rpm related as it happens at 10 mph, 70 mph, and anything in-between with no common condition I can determine. And IDT it's the alternator not actually charging as I'm never seeing just battery voltage.

Anyone have any other ideas? How bad is it to rebuild one of these yourself?
 
I'd normally start with the fusible links(etc) around the battery but I'm fairly confident you've got those under control. ;-)

Gunked up brushes? But yes, I agree it's likely the regulator. Open it up and see what's happening.

From memory they're not that hard to rebuild, I think the regulator and brushes come as one unit, rectifier/diode pack is another, and everything unbolts (rather than having to de-solder anything).
...then again it's been a while since I had the Delica's alternator apart, so let us know what you find out!
 
Growlerbearnz said:
I'd normally start with the fusible links(etc) around the battery but I'm fairly confident you've got those under control. ;-)

Gunked up brushes? But yes, I agree it's likely the regulator. Open it up and see what's happening.

From memory they're not that hard to rebuild, I think the regulator and brushes come as one unit, rectifier/diode pack is another, and everything unbolts (rather than having to de-solder anything).
...then again it's been a while since I had the Delica's alternator apart, so let us know what you find out!
Click to expand...
I've ordered a regulator (brushes and regulator are a module), rectifier/diode pack, and bearings (since I'll have it apart). Total parts cost ~ $100. Not OEM (unavailable); but high quality (Timken/AS-PL)... seems a bargain compared to OEM/rebuilt. Now I'm just hoping it will come out w/o too much trouble.

I can't really get my head around what would cause the lights to illuminate while it is simultaneously charging at 14+ volts...
 
sk66 said:
I can't really get my head around what would cause the lights to illuminate while it is simultaneously charging at 14+ volts...
Click to expand...
That's why I'd also suspect a faulty regulator. The Denso alternator in my Mini has a delay on the battery warning light: if it comes on it comes on for at least a second. I presume that's to make intermittent operation more noticeable.
But I don't think it's a feature of the standard Delica alternator.
 
DustAngel said:
Only other thing that is possible is a short on the wiring? Maybe behind the cluster?
Click to expand...
Maybe; but I would suspect that all of the driving I did on very rough roads would affect an intermittent short. And I would think that a short on the L wire would cause the alternator link to blow (or worse).

FWIW, the way the system works is that a small amount of battery current is sent to the alternator through the warning light (as a current limiter) in order to excite (activate) the electromagnets, which then allows the alternator to function (turn on). When the alternator is not active the magnets act as a ground and the light(s) illuminate. In this situation, any grounding short on the L wire circuit will also cause the lights to illuminate (low current drain).

But once the alternator is running it provides its' own (higher current) power to the magnets (and also on the L wire). Now the magnets are not a ground point and the light(s) go out (protected by reverse current diodes). In this situation any grounding short on the L wire circuit would be a high current short of the alternator (big sparks/blown link). The only way I can see it being a short in this situation would be if it is occuring between the light bulb and its' reverse current diode (which would protect the alternator/link)... IDK exactly where that diode is, but the diagram indicates that it is colocated with the bulb in the cluster itself. And the diagrams also seem to indicate that all three lights using that circuit have their own reverse current diodes... I think that would then mean it would have to be three separate/simultaneous shorts(?).

I could be wrong and making a mistake in my understanding or missing something; if I am, please point it out to me... I would rather not have to pull/rebuild the alternator... and I'm really hoping I don't have the same issues with the stuck pivot bolt others have had recently.

The bitch of it is that it is an "electrical gremlin" at this point... even if I do fix it; I may never know what the actual cause was nor what specifically fixed it.
 
Very good through description of the circuit at hand. In my experience of removing clusters I too have noticed that there are multiple diodes built into the board as mentioned above. Given that it potentially would take three shorts with most likely engine off to create this issue, I believe you are correct into pulling the alternator out and diving further into. I guess it would be possible there is a crack in the regulator? Again, vibration would exacerbate this…
 
Another thought… I believe our alternators start charging once excited with voltage. If there is an intermittent drop of excitement (no pun intended) would the alternator still provide a charge until turned off? If/when the lights on dash come on again, turn the engine off and restart to see if alternator starts charging. If no charging voltage at this point, this could point towards wiring and or cluster issue
 
DustAngel said:
Another thought… I believe our alternators start charging once excited with voltage. If there is an intermittent drop of excitement (no pun intended) would the alternator still provide a charge until turned off? If/when the lights on dash come on again, turn the engine off and restart to see if alternator starts charging. If no charging voltage at this point, this could point towards wiring and or cluster issue
Click to expand...
Once the alternator is spinning fast enough to generate sufficient voltage the magnets no longer need voltage from the battery to stay excited/active... it is self sustaining. But if the light comes on it should mean that the magnets are not being excited by the alternator like they should be (at a minimum)... and that should mean that it cannot generate voltage. Except that the light means the magnets are being excited by the battery/ign sw wiring... which would allow it to generate a charge.

OK, talking through that; it seems like the most likely fault is the F brush (field), or the D+ brush (diode trio); i.e. the F brush not providing voltage, or the D+ not sensing it, but not both brushes or the regulator itself. Since these brushes are part of the voltage regulator assembly on this alternator it's easiest to just replace the regulator (costs ~ ≤ $20). The brushes can be replaced quite cheaply ($5), but it's a solder job and I haven't seen the specs in the manuals (haven't looked hard either).

I figure I might as well do a full rebuild if I'm going through the hassle of pulling it and opening it up (regulator, rectifier, bearings). The cost is less than a cheap chinese alternator, and it should be good for another 30 yrs.

Now, I'm wondering if I should consider replacing the seals on the vacuum pump at the same time....
 
Very good info, this job really becomes a “while your in there” and for the price a full rebuild is a good idea. Let us know what happens, I am curious and thankful for the education!
 
DustAngel said:
Very good info, this job really becomes a “while your in there” and for the price a full rebuild is a good idea. Let us know what happens, I am curious and thankful for the education!
Click to expand...
I'll document the rebuild and parts list when they get here... I did order the new seals for the pump, but still not sure I'm going to open it if it's not already leaking.
 
sk66 said:
I'll document the rebuild and parts list when they get here... I did order the new seals for the pump, but still not sure I'm going to open it if it's not already leaking.
Click to expand...
Look forward to your update, don’t be afraid to open the seal, it’s just vacuum ;)
 
DustAngel said:
Look forward to your update, don’t be afraid to open the seal, it’s just vacuum ;)
Click to expand...
Apparently the large o-ring is about impossible to get now... my order was cancelled/refunded and I've tried a few other sources... the two o-rings are still available from UAE through Amayama, but cost for the two is almost $50 delivered... kinda stupid when you can buy a complete new quality aftermarket pump for ~ $125. If I can't locate the rings (or compatible) for less, I won't be replacing them unless I have to.
 
You must log in or register to reply here.
Top