Fuel Gauge issues - Re-Solved!

[VW_PDX]

Hello All -

it has been a while but i am back in the need of advice. I have read a bunch of post on fuel gauge issues and am still a little perplexed on what is going on in my system. I have a '76 bay westy. the current fuel issue is this:

Fuel gauge stays on empty, except when cranking the engine. So I am guessing this is a short or a mis-wire. I found an example image that leaves me stumped:

I have a similar setup. My wires are black to the vibrator, then a red jump wire to the gauge. However, unlike the above, my gauge is then grounded to the back of the instrument panel. I don't see anywhere, where the gauge or vibrator is getting a signal from the sender. From what I think I understand and looking at the wiring diagram (although that is hard enough to read) shouldn't the brown wire connecting to the back of the gauge come from the sender? Also shouldn't it be brown with yellow stripe?

Edit: I was looking at this diagram that BusDaddy has posted to another forum question that makes me think that my wiring is off: http://www.type2.com/library/misc/vwggauge.htm


I am guess that if the needle moves at all (which it does during crank) then maybe the sender isn't faulty, but that I have some sort of wiring issue.

I will post some images tomorrow or the wiring, but after reading 3 hours fo post I am getting tired and eyes are blurry.

If anyone has advice on what the crank -> needle movement means, I would love to hear it.

Also - I have tried to remove various wires at the vibrator and gauge, to see if anything moves, but nothing happens. I have an alligator clip, so if there is a way I should try to ground it all, let me know.

Pic of the back of the cluster tomorrow.

cheers,
Steff

ps. If anyone thinks it will help, I was thinking of redrawing the wiring diagram for the 76 year (75 production) so it is like my 71 diagram, with actual components drawn out, instead of just the alphanumeric codes and connector numbers. It is so much easier to read than the new ones. I'll post it when I finish, but will need some help with verifying I did it all correctly.
_________________
1978 Westphalia - 1978 engine - 2.0L FI
1976 Westphalia - 1974 engine - Dual carbs
1971 Camper - 1971 engine - Single carb

[Wildthings]

The vibrator gets its power from the S11 fuse and feeds power to the one side of the fuel gauge. The other side of the gauge goes to the sender, via a brown wire.

If you must use that old style drawing then look at the one for the '72 model year. To me it is just easier to look at current track #40 on the new style drawing and see clearly how the vibrator, gauge, and sender are electrically connected. Print the newer style drawing out and then use index cards to cover up everything besides the one or more currect tracks you are interesting in. Easy peasy.


Double click to enlarge

[VW_PDX]

Thanks Wildthings,

I see how the current is supposed to work on both diagrams. So this lets me know that my wiring is wrong if my gauge grounds directly to the back of the instrument panel. I'll need to find the sender wire coming to my panel.

I guess it is just brown. I thought it was brown/yellow. My question is also about the crank position. Would the need le move just because it is getting more power at that point? I'll post photos and move on from there.

cheers!
_________________
1978 Westphalia - 1978 engine - 2.0L FI
1976 Westphalia - 1974 engine - Dual carbs
1971 Camper - 1971 engine - Single carb

[busdaddy]

The wire should be brown/white, it'll be easy to find in the white plastic rectangular connector clipped to the top of the steering column brace.

No idea why it jumps when cranking.
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[JP6210]

[Tcash]

[VW_PDX]

Thanks All for the help.

Upon further investigation, and some sleep I was able to verify that my set-up does indeed seem correct. I think.

The brown wire from the fuel gauge indeed goes to the white plastic coupler (Thanks BusDaddy) and then form there moves on into the main harness. I was mistaken thinking it grounded out directly. That said, my wire is brown / black stripe that comes out of the coupler into the harness as straight brown, which I think is fine. I'll need to get into the tank area to see what color is coming into the sending unit.

So - still outstanding is why would the needle move when the key is in the crank (start) position. I should clarify that it isn't jumping (sorry for poor description) - rather, as long as the key is in the crank mode it slowly climbs up the gauge, almost like it is getting the proper power now and is reading fine.

Does this tell me two things?:
1. when it is getting some power, the gauge works, so that seems to possibly rule out that the gauge itself has a bad needle or something. -- This sound correct / logical???

2. That the vibrator is working correctly, at least in theory, as the need isn't jumping on crank, it is slowly climbing, which is what the vibrator should in fact do, keep things smooth... this also seem sound electrical logic?


-- So I feel like now I am headed towards the sending unit.

So new questions:

3. If I open up the wall behind the engine so I can see the tank. will I have enough visibility and access to connect a jump wire to the brown terminal on the sending unit, so that I can run wire back to the brown terminal on my gauge to make sure that this is indeed all one continuous circuit?

4. If I get my multi-meter to give me continuity sound, then I am guessing the issue may be inside the sending unit itself? (ugggh - didn't want to pull that).

I read on another automotive site (for GM cars) that there is a way to pull a wire that should send the gauge to full? I thought this was the brown wire from the sender, which I removed at the gauge, but this moved nothing.

https://www.fillingstation.com/articles/fuelgaugetesting.htm

[Wildthings]

What is the voltage coming out of the vibrator and going into the gauge? What happens why you do ground out the terminal on the gauge that goes to the sending unit?

The "work when cranking" thing makes me suspect a bad ground somewhere or other bad connection.

[Tcash]

Disconnect the Black wire on terminal #15 on the coil and Tape it up so it does not short out.

Turn the key on to the 1st (run) position. Oil and Alt.
Lights come on jump to #3.
Lights do not come on.
1.Check fuse S11, fuse is good spin it in its holder
2.Clean terminal on the black wire from the instrument cluster to fuse S11

3.Turn the key off
4.Clean the terminals on the Vibrator and fuel gauge.
5.Remove the Vibrator and clean where it mounts to the instrument cluster, the diagram shows this as a ground. Clean the terminals at the white connector.

6.Turn the key on to the 1st (run) position
7.No gauge
9.Jump the black and red wires on the vibrator. Gauge works bad vibrator
10.Jump the fuel gauge Brown/black wire to ground. Gauge works, wiring between gauge and fuel sender bad.

Got it working. Hook the wire back to terminal #15 on the coil.

Good Luck
Tcash

[Wildthings]

[VW_PDX]

Thank you all for great advice - TCash and Wildthings.

Happy to report I have made progress. - I pulled the brown wire from the back of the gauge and grounded that terminal to a ground port on the back of the instrument panel - BOOM - Full tank!

Tested all the connections - all are connecting well. So it seems it was either the sender or the wiring to the sender. So to the back of the bus I went.

Unscrewed the firewall and pulled it down to look inside and see if I could see the sender top and look for issues. Saw the correct ground from the sender top to the bus frame. So looked for the sender wire that should connect to the front gauge. Traced it along to the side of the tank and then nothing... meaning no more wire - It wasn't hooked to anything... WTF???

So to make sure it was the wire and not the sender itself I made a 10 ft jump cable and hooked the end of the wire to the gauge. BOOM - Full tank.

So the wire is operating, and considering I filled the bus yesterday it should be reading full tank. I'll need to run it around a bit to see that it drops correctly. But when I merely grounded the gauge terminal to the panel the needle went above full and off the side of the gauge where I couldn't see it. This is now reading above full a bit but I can see the needle.

You all rock.
I am still going to work on the wiring diagram to make it easier for everyone who isn't an electrically minded person to understand. I am semi-competent and it is still confusing. Plus hard to read the terminal numbers.

thanks all
cheers!
_________________
1978 Westphalia - 1978 engine - 2.0L FI
1976 Westphalia - 1974 engine - Dual carbs
1971 Camper - 1971 engine - Single carb

[Tcash]

[busdaddy]

I'm confused as well.

The sender wire enters the tank compartment through a single grommet on the RH side floor where it slopes up towards the shock tower on a 72+ bus. Pretty well straight down from where the filler neck neets the tank.
_________________
Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
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[VW_PDX]

[VW_PDX]

ok Hoping that you all are still looking the forums and not off prepping turkeys...

New update to my gas gauge. After I found the wire end coming from the sender I took a break. But today I looked into rewiring the sender brown/white line to the instrument panel and came across some oddities.

It seems that the ground on my starter solenoid is heading back through the wiring harness and connecting to the back of the fuel gauge. Yes that is what I found. I can't seem to find this on the wiring diagram.... ??? -- 12 o'clock is the starter control wire, 9 is the battery wiring and 3 is the wire to the starter motor.

The wire coming off at 6 o'clock in the above solenoid, is a brown ground wire that runs all the way up the harness, connects to the white 8 pin coupler behind the instrument panel and then connects to the back of my gauge where the sender wire should connect (brown/black) below:

Does this make sense? Now I know I have 74 engine in, but I don't see in this diagram how that could be the case... I can't seem to find any literature that shows the starter solenoid grounded through the harness...

Can someone let me know if this ground needs to be connected to the starter? I assume it should be grounded somehow, but that harness wire would be very useful to use to hook my fuel gauge back up.

@BusDaddy mentioned that the gauge wire should be brown /white stripe. Seems that my brown/white stripe wire has been co-opted to attach to a relay in the engine compartment that connects to my heater blower. Maybe that is incorrect?

Brown/white stripe eventually winds up in my dash connecting to my heater pull knob at the empty terminal you see below coming off the white plastic:

All very confusing.
thoughts?

cheers!
_________________
1978 Westphalia - 1978 engine - 2.0L FI
1976 Westphalia - 1974 engine - Dual carbs
1971 Camper - 1971 engine - Single carb

[telford dorr]

Most likely that brown wire (this is one time where the 'color code' is violated: brown is not a ground here) isn't supposed to go to the starter (as it's already well 'grounded' to the transmission). That wire is supposed to go to the fuel sender as a signal wire. IIRC, its connecting wire drops down from the body at the frame rail near the starter.

The starter solenoid has no connection to that terminal on your year model.

Brown/white is correct for the blower relay: it should go from the heater control back to the blower relay. Grounding that wire while the engine is running should cause the relay to activate the blower.
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST)

[busdaddy]

There's a strong chance brown/black is the sender wire, the tracer changed now and then over the years but the brown remained the same, brown with some sort of stripe indicates switched or variable ground, lets call that brown/black the correct one for now.

Are you sure that other wire at 6:00 on your starter doesn't go to the double relay? (it should).

Look up at the starter then over to the right side of the bus at the sheet metal above the starter where it starts to slope up towards the shock, there's a single wire (brown/black or brown/white) branching out of the harness or doubling back from the firewall and going up through a grommet into the tank area.
_________________
Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!

Слава Україні!

[Wildthings]

None of the VW wire diagrams are correct as far as the internal wiring in the solenoid. There is actually a second set of contacts in the solenoid that power up the extra male spade(s). On FI engines this spade powers the red/white wire that runs to the double relay and powers the CSV and closes the FI relay while cranking.

The wire you have hooked up to this extra spade terminal probably should go to the fuel gauge as others have noted.

[VW_PDX]

@Wildthing BusDaddy & Telford -

Thanks for all the help. To be clear (and tomorrow I can post more pics, but I think we have this one solved) the wire at 6 o'clock goes from the starter solenoid and straight into the harness. The grommet that leads up to the tank area from the underside is empty, nothing coming through it. I couldn't quite see it when I opened the firewall, maybe the tank was blocking my view, so I routed the sender wire through a convenient tiny hole I found in the firewall.

The brown/white wire that came off the heater pulley up front indeed connects to the relay that is next to my voltage regulator and then relay connects to my heater blower. If I ground that terminal, my heater does indeed go on. So I am going to leave well enough alone and keep that track intact.

Sounds like removing the brown wire from the solenoid won't do any harm, and I have traced it to the gauge, so tat must be what I should be connecting the sending wire to. I am going to route the rest of the sender wire through the firewall hole that the harness stuff goes through and connect to the now located brown wire. Should have the fuel gauge back in action tomorrow.

Thanks a bunch. You are all so great with your effort to help out with learners like me.

Tomorrow I will post about the blue wire and the grey and black wires that I found stranded at the end of the harness by the starter... I think blue is fr some kind of warning light and grey/black not sure. need to look over the diagram again....

BTW - I have gotten an schematic of a bay bus from all sides. I am working on an electrical view that has all parts in position, so people can see what is supposed to be where. Eventually I will break it down into layers, so you can see each system/current for troubleshooting.

cheers!!!
_________________
1978 Westphalia - 1978 engine - 2.0L FI
1976 Westphalia - 1974 engine - Dual carbs
1971 Camper - 1971 engine - Single carb

[1970bay]

My guage has always jumped about igniotion on then ok,UNTIL i had use the lights then the indicator goes to full

By turning the instrument light ajustment it will breifly show true ? Fule leval I think as the light is so dim i cant read the speed'unlil passing under a street lamp
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Travels with my camper:
http://flickr.com/photos/30879804@N08/

Built in 1971 The engine was changed from 1600cc to a 1972 flat 1700cc engine in 1974 otherwise nothings been changed std twin vw carbs