High Beam Indicator Bulb; Check troubleshooting logic please?

[Vanagon Nut]

Hi folks.

edit: this is for a 1988 Vanagon.

Can someone check my trouble shooting logic please?

I don't want to remove the blue foil circuit to replace the bulb unless absolutely needed.

Previously, i ran new fused + wires from battery to high/low beam relays, installed round headlights. Since I wanted to keep the OE square headlight wiring intact, I foolishly cut into the high beam switch wires to trigger the new relays. The blue high beam bulb worked after that but after some time, it got dimmer then stopped lighting up. I'd previously assumed I'd done something wrong with my relay wiring work.

Cluster on the bench:

- ground path from T 14/3 to end of 100 Ohm resistor shows 100.x Ohms
- ground path from T14/3 to pre resistor shows 0.00 Ohms
- 12 volts applied to ground at regulator ground and positive to high beam bulb leg contact does not light the bulb

at T14 connector on van:

- white wire from high beam switch is connected to 56a path to blue/white wire at T14/2. I see 12 volts at T14/2 when I engage the hi beam switch.


The bulb has failed right?

I've never had a warning/indicator bulb fail so I'd assumed they lasted a very long time.

Neil.
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1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN

[crazyvwvanman]

The high beam uses an incandescent bulb and burns out far more often than the other cluster indicator bulbs which are leds.

Mark

[Vanagon Nut]

Thanks Mark.

Ok so I went outside to freeze my hands off and found what you wrote of; the white bulb and blue cover.

My spare late '85 ribbon appears to have same, and that bulb appears to be burned out. One of my spare older cluster ribbons has a blue high beam LED using a 270 Ohm resistor, IIRC. Not that I can use that bulb anyways.

I found a dead (404) van-cafe link for that high beam incandescent bulb. I might wire in a temporary bulb until I decide on, or truly need, something like this

https://www.vancafe.com/255919059AFT-p/255919059aft.htm

Or wire up a VW "cucaracha" song relay for the high beam indicator. That would make long late night trips interesting.

Neil.
_________________
1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN

[Vanagon Nut]

Is ~ 0.028 Amps the maximum current you can reliably put through the warning light LED's ?

Looking at my spare blue ribbons, and here;

https://www.thesamba.com/vw/forum/viewtopic.php?p=6895131&highlight=ohms#6895131

I see violet yellow brown 470 Ohm resistors used for the LED warning bulbs.

Except for the later style incandescent high beam warning light bulb, all other warning lights look the same or very similar. I assume the resistor for the oil light on Vanagons with the oil "L" board use a resistor on that board.

On my spare '85 ribbon, the high beam bulb disintegrated as I tried to remove it; I never did find the bulb legs (contacts). But the socket used for both rows of warning lights look the same and have the same part number. A red, green, yellow LED warning bulb seems to fit reliably in the incandescent high beam socket.

Neil.
_________________
1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN

[Vanagon Nut]

.... worthy of note; it appears the polarity at the later style high beam bulb socket is reversed; one would need to turn the LED warning light bulb 180º when installing it.

Neil.
_________________
1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN

[Vanagon Nut]

[crazyvwvanman]

You can use a little 9 volt battery to test, at the 14 pin connector.
Battery - to the ground pin, battery + to the pin for high-beam.

Mark

[Vanagon Nut]

Thanks Mark. Good tip. True to my form I used an old car battery to do same by connecting it to the supply end of the LED resistor and (edit: ground? can't recall polarity) on blue ribbon. Not as convenient as using a 9 volt battery. LOL. Testing via the 14 pin connection makes far more sense; might as well determine if the copper traces etc on ribbon are ok.

I'm so careful about polarity but tend to forget that an LED won't be harmed by accidental reversed polarity. (uh, like "D" is for "diode" )

Neil.
_________________
1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN

[crazyvwvanman]

The blue foil is way too delicate for me to test things with a big battery. A small mistake and POOF

You could use a small fuse on the power from the big battery, for testing things that need more than 9 volts, like the gas and fuel gauges.

Mark

[Vanagon Nut]

[Vanagon Nut]

Well, possibly a bit of egg on my face.

This is for an '88 Vanagon.

I didn't check the resistance value of resistor in the incandescent bulb circuit.

The Vanagon LED high beam warning light I installed in that circuit is now starting to flicker on/off, mostly off.

Anyone know the resistance value of resistor to the high beam incandescant bulb as used on later model years?

I don't want to disturb the cluster, again, but may be able to read the value with a mechanics mirror.

Neil.
_________________
1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN

[80_Westy]

This is interesting to me. I replaced a red LED in my high beam indicator with a blue one I bought at Microcenter that is the right size, but it is way too bright. I didn't realize it was supposed to be an incandescant blue lamp. Now that I think about it, they didn't have blue LEDs in 1980. The 2014 Nobel Prize in Physics went to a Japanese team that invented blue LEDs in the early 1990s.

So I've made a bad assumption. Looking at the manual, there are 3 LED indicators and the K1 is described as "bulb (blue) high beam". And the resistor for thar one is 270 ohm. The 3 LED resistors are all 470 ohms. So either replace the resistor on the disintegrating plastic circuitboard, or get the right light.

Or, paint over most of the bulb to emit the right amount of light. It's really too bright.
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1980 Westfalia Assuan Brown

[Vanagon Nut]

[crazyvwvanman]

Instead of messing with the delicate foil to add a higher value resistor you can just add another resistor into the wire that goes into the 14 pin connector.
The blue/white wire. Add a 220 ohm or 270 ohm.

Mark

[Vanagon Nut]

[80_Westy]

So a little more research indicates that different LED colors require different "forward voltages" to turn on. The resistor is used to set the voltage drop from the supply voltage from the voltage stabilizer on the back of the instrument cluster -- per Bentley should be 10.0V. A stable voltage will fix the current at the same level and the LEDs will always have the target Forward current and thus the correct brightness.

A calculator I found indicates how to measure the LED forward voltage with a multimeter. Www.petervis.com/electronics/led/led-resistor-calculator.html

You have to measure or lookup the Forward voltage requirement and "continuous duty cycle maximum IF current". For myself, I bought red, green and blue 3mm LED bulbs from the NTE electronics family, numbers NTE30031 green, NTE30036 blue and NTE30034 red. They recommend 20 mA current. The VF for red is specified as 1.86 V, for green as 3.5 and blue at 3.3V to pass those currents.

My calculations indicate that a 500 ohm resistor is needed for the green and blue LEDs, if you use the ones I got. Probably the 470 used for the circuitboard fir the green turnsignal lamp is OK too. But if you have the 270 ohm resistor for the incandescent lamp, you will get a really bright highbeam indicator like I have, or burn it out. YMMV if you get some other brand or size.
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1980 Westfalia Assuan Brown

[80_Westy]

I am saying that according to my 1980 Bentley page 90.8 fig 4, there are supposed to be 3 LEDs and one blue incandescant "bulb". The lamp had pins like the LEDs and you can stick an LED into the sockets because it fits. But they didn't have blue LEDs in those days. When I put a blue LED in there to replace a non-working one a PO had there, it was wayy too bright. Now I understand why-- the resistor is too small, it should be about 500 ohms instead of the 270 ohm one that is in there.

My green Bentley 90.18 Fig 4 also shows for later watercooled Vanagons from 1985, they still had 1 blue "bulb" and now 4 LEDs (added 1 yellow K29 glow plug indicator for diesels I guess).

Because the holder for the high-beam indicator bulb fits an LED, I assumed it was supposed to take an LED, and that mine is too bright because I had the wrong one. My bad, they didn't have blue LEDs back then. They weren't invented yet.

Ed. Spelling

To retrofit an LED requires changing the resistor. You could add a 200 or 230 ohm one in series at connector 56a where the indicator wire comes off fuse S5 on the left high beam circuit. Added to the 270 on the circuitboard, you would be at 470 or 500 Ohms. I haven't tried yet.
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1980 Westfalia Assuan Brown

[crazyvwvanman]

If adding an extra resistor the place for it is in the blue/white wire that goes to the 14 pin connector so that the only thing affected will be the high beam indicator light.

The 10v voltage stabilizer only powers the fuel and temp gauges, not any lights in the foil. In any case the high beam indicator gets it's power from the headlight circuit, not from the cluster power.

There are some errors in that 90.xx section that also shows the various leds/resistors for various models so don't take all the info there as gospel.

Mark

[Vanagon Nut]

I'm currently installing this 5mm 5 volt 30 mA bulb in the K1 hi beam indicator socket:

pdf file to specs:

https://www.osepp.com/downloads/pdf/HT333%20-BLUE.pdf

So engine running: 13.5 V - 5 V = 8.5 Volts

8.5V / .03 Amps = 283 Ohms.

Using 12.5 Volt source, bulb will light but be dimmer, with a ~ 2000 Ohm resistor.

For the sake of having it dimmer while driving at night....

To confirm, and I'm nearly certain the answer is "no" but......

Using a higher value resistor (~ 2000 Ohms) in the K1 hi beam circuit won't cause that resistor to heat up right?

Neil.
_________________
1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN

[fxr]