Fuel Gauge Troubleshooting

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drober23
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Location: Metro Detroit
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Fuel Gauge Troubleshooting

Post by drober23 » Sat Mar 02, 2013 6:05 pm

Time to sort out the non-operating fuel gauge on the '75 Westfalia.

So, I look up Jamie Rivers troubleshooting article, and BANG, no power to the vibrator. I notice there is a brown wire with a black stripe connected to the vibrator. Should be a black wire, got something to go on.

**edited shortly after posting** The wiring diagram does not show a brown/black wire, but searching here and at that other site suggests the brown/black wire is supposed to go from the Gauge to the Sending unit. So, it looks like I mixed up the black wire to the vibrator and the brown/black wire to the gauge.

This explains why my gauge read full for about 27 seconds when I connected it last year, then went to E and has stayed there since. Is it safe to assume the gauge is toast? Could it be repaired. If not, I have another gauge I can swap in.
DJ

'75 Westfalia, '79 Deluxe
(plus more busses than sense)

In a time of chimpanzees I was a monkey

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Amskeptic
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Re: Fuel Gauge Troubleshooting

Post by Amskeptic » Sun Mar 03, 2013 10:24 am

drober23 wrote:Time to sort out the non-operating fuel gauge on the '75 Westfalia.

So, I look up Jamie Rivers troubleshooting article, and BANG, no power to the vibrator. I notice there is a brown wire with a black stripe connected to the vibrator. Should be a black wire, got something to go on.

**edited shortly after posting** The wiring diagram does not show a brown/black wire, but searching here and at that other site suggests the brown/black wire is supposed to go from the Gauge to the Sending unit. So, it looks like I mixed up the black wire to the vibrator and the brown/black wire to the gauge.

This explains why my gauge read full for about 27 seconds when I connected it last year, then went to E and has stayed there since. Is it safe to assume the gauge is toast? Could it be repaired. If not, I have another gauge I can swap in.
Why? Why assume? Hook up the wiring correctly and test. You can test on the spot. I calibrate every gauge with my customer when we are back there.

For reference . . . every brown wire since forever is a ground on a German automobile.
Every brown + black stripe is a variable resistance ground on a German automobile.
Colin
(usually) :alien:
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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drober23
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Location: Metro Detroit
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Re: Fuel Gauge Troubleshooting

Post by drober23 » Sun Mar 03, 2013 5:32 pm

Ran to Radio Shack for some resistors and tested stuff.
The vibrator was fine, and the gauge was toast. I found a spare I didn't know I had!

With about 2 gallons of gas, the gauge shows about 1/8" red to the left of the needle in the R section. Drove the bus to town and filled it up. With the tank full, the gauge reads solidly above full. Should be good!
DJ

'75 Westfalia, '79 Deluxe
(plus more busses than sense)

In a time of chimpanzees I was a monkey

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