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MG MGB Technical - Wiper and fuel gauge issue.

Hello all, been a while since I posted something.

My wipers aren't working. There is no noise or anything when I put them on. What could it be?

And like above my fuel gauge is not working. Same as above, what do I ned to do?
MD Rice

Green circuit fuse?
Chris at Octarine Services

Anything else not working...indicators, brake lights?
Dave O'Neill2

Everything else is working. All the lights, everything electrical except the wipers and fuel gauge.
MD Rice

MD- What year is your car?

Brian Shaw

Hi,

A quick look in the Advance auto wire files, came up with a 69-71, as having the wipers and fuel gauge electrics in common. Also the temp gauge. There is a green wire that goes to the voltage stabilizer and daisy chains to the wipers. If this wire is open at the far end then no power gets to the voltage stabilizer and the wipers.

http://www.advanceautowire.com/mgb.pdf

Herb
Herb Adler

Temp gauge is capilliary for a UK 69-71, not electric until 77.

As Brian says we need to know the year of the car, and if not an RHD, as there are some 20 schematics that could apply.
Paul Hunt

Paul I'm going to send Ricey links to your schematics

it's a 1973 car (not sure if that's actual or model year) BGT and I think UK car

something I've never been sure about, voltage stabiliser does it need to be fitted on the horizontal/vertical or it doesn't matter
Nigel Atkins

Voltage stabilizer does not care :)

Terminal B is to (B)attery
Terminal I to (I)nstruments

Bernie
B Anderson

fair enough, I wasn't sure as some have 'Top' stamped on them
Nigel Atkins

It may simply be a gummed up rack and pinion. Considering that the grease is almost 40 years old, it is not unusual for this to occur. Try moving one of the wiper blades while the switch is in the on position. I hadn't used my wipers in over ten years, since the car never sees rain. When I did turn on the wipers, I got no response until I gently applied some pressure to the wiper blade. The wiper system instantly came back to life. Worth a try. RAY
rjm RAY

In that case as far as the wipers go it could be the in-line accessories fuse that is blown, should be below the fusebox. From 1970 to 74 or rubber bumpers the heater fan and wipers were powered from the accessories position of the ignition switch, and not the green 'fused ignition' circuit of the fusebox.

Voltage stabiliser *does* care about orientation - at least the original thermal units do. They should hang down from the mounting tab, and be marked 'TOP'. They will still work, but the 'stabilised' voltage may well vary.

Aftermarket electronic stabilisers don't mind, nor flashers.
Paul Hunt

cheers Paul, you may be interested to hear that one B owner has put that he's had an electronic stabiliser fail after 3 months, it was tie-wrapped to the bar under the dash, another B owner said he had two fail because they don't like vibration but that once cable tied to the loom it was never any more trouble

in my Spridget my electronic stabiliser just hangs off the wires and spade connectors and has been like that for over 4 years and many thousands of miles

Growler also told me that the electronic version vary with temperature where as the old style bimetallic ones don't (or not as much, can't remember)

I only use my gauges as just that a guage so haven't noticed, when you have less than 6 gal tank the fuel gauge moves quite quickly anyway
Nigel Atkins

n my Spridget my electronic stabiliser just hangs off the wires and spade connectors and has been like that for over 4 years and many thousands of miles

I hope that you have the case earthed, or it won't regulate.

Growler also told me that the electronic version vary with temperature where as the old style bimetallic ones don't (or not as much, can't remember)

Yes the electronic ones do vary with temp, about 0.4mV per degree.

Herb
Herb Adler

Does a '66 have an electronic stabiliser? If so where is it? My fuel gauge reads "Full" when key is on at all times.
David Werblow

Herb,
I think my electronic VS has a earth wire, can't remember so long ago since I fitted it

I've not noticed any difference in the gauge but then I use all the gauges as just gauges of what's going on


David,
not as standard, the electronic stabilizer is modern alternative to the original bi-metallic strip voltage stabilizer fitted originally, see Paul Hunt's excellent site - http://www.mgb-stuff.org.uk/electricstext1.htm#stabiliser

the VS is fitted somewhere behind the dash, it's pushed into a metal clip case that is screwed or welded to the body to proved and earth to the stabilizer's metal body, the VS has to be fitted the correct way up (I learnt here recently) and you have to have the correct one for your model of car

showing full could mean problems with wiring or connection but follow Paul's diagnostics here - http://www.mgb-stuff.org.uk/electricstext1.htm#diagnose

there is just so much info on Paul's site it's almost endless

Nigel Atkins

Hi David,

On my 66 it is bolted to the firewall, above the pedals. A tin box about1 X 2". Yours, being LHD, might have it above the pedals, or in the corresponding position in the passenger's footwell.

For interest I've just worked out the approximate error due to temperature variation, over a 40 deg C span. It works out to be ~96cc, or less than half a cup of petrol.

Herb
Herb Adler

Herb,
is that more petrol in the tank or less as the fuel gauge is right in front of where my wife sits and I get audible warnings as soon as the gauge gets to the half mark, she'd be please to know it's under reading by about 100cc - for about half a second until she'd worked it out

my car's also got audible speed limiter, we call it the 'verbal handbrake'
Nigel Atkins

No MGB had an *electronic* stabiliser from the factory, but they did have the thermal stabiliser from some time in 1964, green and light-green/green wires. It can be high up on the firewall behind the dash, not very accessible, better on later cars where it is on the lower edge.

The thermal stabiliser (and thermal gauges) are temperature compensated, in quite a cunning way. The bimetal stip is U shaped, fixed to the gauge body at one end of the U, with the needle attached to the other end. So as the bi-metal responds to temperature both halves of the U bend an equal amount, the middle of the U moving, but the two ends staying together. The heater wire is wrapped around the gauge half of the U, so the gauge end of the U only moves the pointer from heat from the heater.
Paul Hunt

This thread was discussed between 16/06/2013 and 19/06/2013

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