11 replies to this topic

[westlin]

I am fitting Smiths gauges to my sons car but just want to confirm the correct way to wire them.

The gauges are as follows:

Fuel gauge
oil temp
water temp

all are being fed by the voltage stabiliser, but which way should their terminals be connected ( there is nothing obvious markings on the back of any of them) and do they need an earth connector.

Thanks

[Spider]

The gauges are not polarised, so you can connect them either way around.

 

This might also be of help

 

 

I think a similar one is in FAQ ;)

Edited by Moke Spider, 24 January 2016 - 05:45 PM.

[westlin]

What about the earth, not clear in the diagram

[Spider]

The Gauges themselves are not directly connected to Earth, they are connected to the senders which in turn are Earthed.

[westlin]

Ok, thanks. Is there anyway of checking the fuel gauge in isolation of the sender?

[dklawson]

As above.  The sending unit is the earth connection for the readout portion of the gauges.  

 

You will need to provide an earth to the gauge casings if you plan on illuminating the gauges.  The case is earthed and lamp's red wire connected to the dashboard lighting circuit.  The most common way to earth a 52mm gauge is to make a black wire with a ring terminal on one end which is secured to one of the gauge mounting studs on the case.  The other end of the wire is earthed to the chassis of the car.

[dklawson]

To check the fuel gauge, wire it as shown on Spider's schematic.  In the boot of the car, locate the green/black wire on the sending unit.  It is the wire going to the gauge.  WIth the ignition on, earth the disconnected end of the green/black wire.  If the gauge goes to full, it is working.

 

EDIT:  My comments assume you have retained the stock wiring color codes.

Edited by dklawson, 24 January 2016 - 07:06 PM.

[Spider]

You will need to provide an earth to the gauge casings if you plan on illuminating the gauges.  The case is earthed and lamp's red wire connected to the dashboard lighting circuit.  The most common way to earth a 52mm gauge is to make a black wire with a ring terminal on one end which is secured to one of the gauge mounting studs on the case.  The other end of the wire is earthed to the chassis of the car.

 

Doug, on the Older Gauges the case did have to be Earthed, but the new ones don't. They come with two wire bulbs these days, I'd guess because there's many more 'plastic' dash boards popping up.

[westlin]

I've earthed the bulb so that covers that. Ill check the boot wire to earth and see if it works

[dklawson]

Two wire dash lighting?  That's pretty nice actually.  Those same bulb holders could be used for things like ignition warning lamp and low oil pressure warnings.  Am I correct that being later lamp holders they also take the later type "push-in" type bulbs?

 

EDIT:  Remember when checking the fuel sending unit and fuel gauge, that the sending unit has a black earth wire that goes to the car's chassis.  That black wire connects to the non-insulated spade terminal on the sender.  The second spade terminal on the sender will be on a plastic block.  It receives the green/black wire coming from the gauge.

Edited by dklawson, 24 January 2016 - 07:18 PM.

[westlin]

Im sure my sender has 2 different size spades, so I tbink they are the right way round

[Spider]

Two wire dash lighting?  That's pretty nice actually.  Those same bulb holders could be used for things like ignition warning lamp and low oil pressure warnings.  Am I correct that being later lamp holders they also take the later type "push-in" type bulbs?

 

It's good and bad in my books, probably a little more reliable I guess. From memory, the bulbs are a miniature bayonet. I have a load of new gauges in the workshop ATM for a build under way, I'll try to remember to snap off a couple of photos.