Fuel gauge wiring

[fallingoffalot]

I've just got round to installing my early bay gauge in the late bay cluster (I know it won't fit but I'll think of something when I know it works). Any ideas where the red and green wires connect? (Couldn't find anything obvious on line!)

Thanks

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[sparkywig]

Red 12V, Green to sender?

 

[fallingoffalot]

Here's a picture of the back of the dash, fuel gauge has a red, and brown going to it, I think the red then connects to the vibrator(?), the red reads 10.4v. Which wire is the sender? Is it the brown, or the other wire going into the vibrator, if that's what it is.

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[sparkywig]

Have a look at the wiring diagram.
All years available here.

https://www.thesamba.com/vw/archives/info/wiringt2.php

 

[fallingoffalot]

Thanks, I have a look tomorrow when it's a bit warmer in the garage. The diagram in the Haynes manual is useless as there's no colour.

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[fallingoffalot]

Ok here's my new fuel gauge. Green (yellow) wire going to sender. Red wire to 12v, rear screw thread earthed. If I earth the sender it goes to full, but otherwise nothing.

Anyone any ideas?

(Update) the sender is reading 125 Ohms, I thought it should be 0-90. Could I have a late bay sender?

(Update) The sender is reading open-circuit, therefore I guess buggered.

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[brittas]

Hi , I know I'm a bit late on this but have just completely rewired my bus so have got it in my head at moment .The fuel gauge is basically a volt meter that requires an ignition feed ( 12volts ) brown/red and an earth out through the fuel tank sender ( variable resistor ) . The resistance range on the sender will match the gauge , might be a problem inter changing them from different years ? Had to strip my sender down as it was not working , basically they are a float that travels up and down a length of taut wire . When at the top , tank full , full length of wire so maximum resistance . When at the bottom float offers a short cut across wire so resistance is the least . Earths in general are a problem area on older vehicles as they rely on contact with the chassis , so prone to corrosion . Hope this helps , Brittas

 

[ozziedog]

Hi , I know I'm a bit late on this but have just completely rewired my bus so have got it in my head at moment .The fuel gauge is basically a volt meter that requires an ignition feed ( 12volts ) brown/red and an earth out through the fuel tank sender ( variable resistor ) . The resistance range on the sender will match the gauge , might be a problem inter changing them from different years ? Had to strip my sender down as it was not working , basically they are a float that travels up and down a length of taut wire . When at the top , tank full , full length of wire so maximum resistance . When at the bottom float offers a short cut across wire so resistance is the least . Earths in general are a problem area on older vehicles as they rely on contact with the chassis , so prone to corrosion . Hope this helps , Brittas

Ozziedog,,,,,,,,Great reply, even I understood that :mrgreen:

 

[brittas]

Hi , just read my previous , brown / red is the earth out through the tank sender , ignition feed is normally black (15) on wiring diagrams. After looking them up , late bay buses have a float on an arm that moves the variable resistor by turning it ,so work differently . I have fitted an access panel above sender into the bus for better access to it , nothing more annoying than taking engine out just to get to a problem sender !. Brittas

 

[fallingoffalot]

Thanks brittas, useful info. I am planning on cutting and fitting an access hatch - a little nervous about getting the hole on target, but there's plenty of info about where it's located. Problem is in the past some of the early features have been updated to late features - like the wheels, brakes, dash. So I'm not sure what I'm going to find really. At the moment I am working on the 200 mile rule - writing the mileage down on the dash with a dry-wipe marker pen (and running out occasionally)!! I've learnt a load more about the electrics now having successfully fitted my oil temp gauge and finding out that black is switched live not earth!!

 

[67panel]

Yes brown earth, black ign live and red bat live. There is an earth wire from tank to body with ST screw and they get corroded . The little box on back of instrument cluster is a voltage regulator, drops it to 10volts I think and this means that as voltage goes up or down the gauge reads steady.

 

[brittas]

Thanks I didn't know about voltage regulator , that makes sense .As the wife and I got bus for touring in when its finished , it's been a learning curve .I was a mk1 golf man so all gauges where more modern hot wire or voltage balanced ones . The regulator would keep the voltage at a constant 10 volts and stop the gauge being affected by alternator charging voltage changes .( full batt charging +14v back to 12v when battery back fully charged )