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Wema UK · Help

Gauge wiring & installation

How to mount a standard Wema gauge in the panel and wire it up — the diagram, the colour key for every wire, and the fitting steps.

Gauges·Installation

A standard Wema gauge drops into a 52 mm panel cut-out and wires up with five connections — power, ground, the sender signal, and your choice of backlight colour. Here's the diagram and how to fit it.

Isolate the supply before you start wiring, and double-check the connections against the diagram before powering up.

01Wiring diagram

Standard Wema gauge wiring diagram Tap the diagram for a larger view

02What each wire does

  • Red — to positive (battery +)
  • Blue — to ground (battery −)
  • Black — to the sender
  • Yellow — yellow backlight
  • Orange — red backlight

You only connect one of the two backlight wires — whichever colour you want lit. The wire colour matches the backlight colour it gives.

You can dim or switch the backlight, too. Fit a dimmer — a variable resistor — in line with the backlight wire to set the brightness, or wire a switch to select between the amber (yellow wire) and red (orange wire) backlight.

03Installation steps

  1. Cut a 52 mm (2¹⁄₁₆") diameter hole in the panel. You'll need a minimum clearance of 55 mm (2³⁄₁₆") behind the panel to fit the gauge.
  2. Remove the fastening ring, insert the gauge through the panel from the front, then fit and tighten the fastening ring from the rear.
  3. Connect the wires according to the diagram, choosing either the orange or yellow wire for the backlight colour you want.
  4. Insert the wire harness into the port at the back of the gauge.
For the gauge to read accurately it needs a clean, steady supply — a low or fluctuating voltage will throw the reading out. If you're running several gauges, a single voltage regulator can feed the whole dashboard. There's more on why in the importance of voltage regulators.

The gauge

Wema gauges & displays

Analogue and multi-function gauges for fuel, water, oil pressure, voltage and more — paired with the matching sender.

Browse gauges View voltage regulators

04Common questions

What size hole does the gauge need?

A 52 mm (2¹⁄₁₆") panel cut-out, with at least 55 mm (2³⁄₁₆") of clearance behind the panel. (A tachometer takes a larger 85 mm hole — see tachometer wiring & installation. For a voltmeter, see voltmeter wiring & installation.)

Which wire is the backlight?

Both the yellow and orange wires are backlight feeds — connect just one. Yellow gives a yellow backlight, orange gives a red one. You can also fit a dimmer (a variable resistor) in line to control brightness, or a switch to swap between the two colours.

Which wire goes to the sender?

The black wire. Red goes to positive, blue to ground, and black carries the signal from the sender to the gauge. (A voltmeter is the exception — it has no sender; see voltmeter wiring & installation.)

My reading is wrong or unsteady — where do I start?

Check the supply voltage first, then the earth and the signal wire between sender and gauge. See how to test a gauge.

Not sure which wire is which on your loom, or which gauge you've got? Get in touch and we'll help you wire it up.