OXS and Battery Light / Alternator

[Seelenbrandt]

After pulling my '84 Westy of of hibernation this winter I noticed that both my OXS and battery light are on. The V-belt seems snug and tight and the infamous blue wire seems to be corrosion free and making good contact. Could it just be that the alternator is going or has gone bad? Would this cause the lights to be on? Also, I don't really get any flicker when revving the engine. I have not driven it more than 2-3 times since April, but the battery was dead when I went to start it today. Also curious, if the alternator is bad, does that affect the water pump in any way? I know they both run off the same belt. Just hoping to run the van up to the lake this weekend and don't want any major issue. Any help would be greatly appreciated.
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1984 Westfalia

[MarkWard]

If you disconnect the blue wire at the alternator with the key off and then turn the key on do the lights not light? Make sure the blue wire does not touch a ground during this test.
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[Seelenbrandt]

Thanks for the advice. I unplugged the blue wire without the key in and restarted - both lights are still on.
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1984 Westfalia

[MarkWard]

Then it's likely not the alternator. Still best to see if its actually charging. Something else is going on with the indicator light.
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[Seelenbrandt]

Mark also let me know that I should also mention that my temp gauge has been acting funky too. The gauge usually red lines and then goes back to normal after driving for 5-8 minutes.
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1984 Westfalia

[Seelenbrandt]

My next plan is to test the alternator, but I am stuck at home with the kids and the battery in my voltage meter is dead. Hoping to check later this evening.
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1984 Westfalia

[MarkWard]

This is a stretch diagnosis, but the 84 might have the OXS counter in the speedometer cable. It's a black box next to the spare tire on the l/s. Its design was to turn the OXS light on every 30000 miles I recall. There is a pushbutton reset to turn the OXS light off. I don't think it would turn the alt light on, but they are tied together for a bulb check on startup.

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[Seelenbrandt]

Yeah, that was the first thing I tried. Pushed it in, heard the click - light still on.
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1984 Westfalia

[MarkWard]

Try unplugging it. Troubleshooting is often a process of elimination.
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[erdonline]

The oxygen sensor light can come on by itself because of the mileage counter, but the alternator light only comes on with the oxygen sensor light because of the bulb check feature. So if both are on, it's because of the charging system.

Ed
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'85 Vanagon Westfalia
'84 Vanagon 7-passenger
'98 Mexican air-cooled Beetle

[MarkWard]

Disconnecting the blue wire from the alternator should have turned the warning light off. Somehow that circuit is getting a ground before the alternator. Time to start eliminating possible sources. If unplugging the counter box doesn’t help, I’d be looking at the relay under the driver’s seat if it’s a camper.

You can also test the alternator output with a voltmeter and using a simple test light connected between power and the D+/ blue wire terminal on the alternator. That load should excite it into changing independent of the cluster.
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[crazyvwvanman]

In Westy models and some others there are relays that connect to the alternator blue wire circuit.
On these the light can stay on even with the blue wire unhooked from the alternator.
This makes the troubleshooting a little more difficult.
In most Westys you can easily unplug the blue wire from the fridge relay to help you figure out what is going on.
Same with models with factory aux battery setups.
These are generally found under the driver seat.

Mark

[Seelenbrandt]

I was finally able to test the alternator with a multimeter. Definitely not charging while running. Drops down below 12 when the van is running. Is this definitely an alternator replacement situation? The alternator does not sound clunky. Could it be a wiring issue? Could it be the voltage regulator?
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1984 Westfalia

[crazyvwvanman]

The blue wire is the key at this point.
The blue wire provides a small signal to kick the alternator into charging.
If the blue wire isn't providing that kick start then the alternator can appear to be dead when it is really fine.

The blue wire gets power from the dash cluster and this is what is sent to the alternator to kick it into action.

Mark

[Seelenbrandt]

Thanks Mark! Time for some blue wire sleuthing!
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1984 Westfalia

[Seelenbrandt]

OK - I finally got around to testing where in the line my issue is. I disconnected the blue wire at the box in the left rear portion of the engine compartment. When I did, my lights went off. So obviously there is an issue with the blue wire, right? Everything looks tight on the alternator end of things. So my next course of action is to replace the blue wire? Can I replace just the alternator field wire instead of the whole harness? If so, what do I need to know about the wire itself? Is it 16 gauge copper? Thanks!
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1984 Westfalia

[hardway]

Hi.

Have you tried removing the regulator from the alternator? Two screws. If one of the brushes does not reach, the alternator will not charge. The alternator needs to be supplied with the initial current of excitation to get it going. With the blue wire off or on you can jumper from the B+ post on the alternator (assuming that it is connected to the battery) while the engine is running. This would energize the field. If the alternator can charge, at that point it will. Test the alternator output with the voltmeter leads on the B+ terminal and the alternator body (B- or ground). That way you have eliminated all other external phenomena.

[Seelenbrandt]

Still looking for a little advice on my OXS/ battery light issue. Some of the past advice said to disconnect the blue wire from the alternator to see if the light goes off. It did not. However, when I disconnect the wire at the box in inside the engine compartment it goes off. My question is this - does this mean the issue is definitely between the alternator and the box? Or is it possible that it is further up the line. I cut some 16g copper wire today to test between the alternator and the box and the issue continued. I'm not super experienced on the electrical side of things, so I'm not sure if I connected things in a reliable way. Any help would go along way to ease my head banging.

In regard to the previous post about the brushes not reaching - would that make both lights come on?

Thanks!

Glen
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1984 Westfalia

[slomoracing]

It does not definitely mean that the issue is between the box and the alternator but I’d say all signs point to yes.

[87syncro]

Hi Glen, So what was the problem and how did you figure it out? I'm trying to figure the same symptoms out without throwing parts at it. Thanks, mike