Multifunction Gauge Backlight

[Jason2tpa]

Is it possible to replace the backlight in this gauge? If it's not lit by a bulb, instead being powered by some other means, is there a wire I can test that powers the 'some other means'?

[rodbolt17]

blue is positive and black is ground for the back light.
uses 12V.
no replacing the lamp.

[Jason2tpa]

This tach was a hand-me-down after my previous tach faded out. Works great, except no backlight. It was free, so no complaints. But I'd like to figure out if its a bad backlight, bad wire, and confirm its connected correctly.

The dialogue below comes from the installation manual for my tach. The highlighted statement is confusing me.





The picture below is of the connections between the tach and tach signal harness. Blk-Blk, Yel-Yel, Blu-Blu, Grn-Grn. Simple. But I do not have the yellow and blue wires in the middle of the harness connected, as this manual suggests if wanting the backlight on with ignition.




My next question has to do with meter testing the blue wire. I know the tach and tach harness black ground wire is good because the tach works. Since the blue wire carries 12v for the backlight, I can volt test the harness blue to confirm it's delivering 12v. If the harness blue is good, how do I test the tach side blue wire?

[Jason2tpa]

This tach was a hand-me-down after my previous tach faded out. Works great, except no backlight. It was free, so no complaints. But I'd like to figure out if its a bad backlight, bad wire, and confirm its connected correctly.

The dialogue below comes from the installation manual for my tach. The highlighted statement is confusing me.





The picture below is of the connections between the tach and tach signal harness. Blk-Blk, Yel-Yel, Blu-Blu, Grn-Grn. Simple. But I do not have the yellow and blue wires in the middle of the harness connected, as this manual suggests if wanting the backlight on with ignition.




My next question has to do with meter testing the blue wire. I know the tach and tach harness black ground wire is good because the tach works. Since the blue wire carries 12v for the backlight, I can volt test the harness blue to confirm it's delivering 12v. If the harness blue is good, how do I test the tach side blue wire?

[Jason2tpa]

I know rodbolt said the backlight cannot be replaced, but I found a thread on my aquasport forum where the member replaced the light. The bulb socket is pictured below, circled in red.

That gauge pictured is not the same as mine, his being the 2 push button model. But it might be possible my tach, which is older than the push button model, has the bulb in the same spot.

Rodbolt....to your knowledge, why is the lamp not replaceable?

[Jason2tpa]

Out of curiosity I connected the blue and yellow pigtails together, the two pigtails located in the middle of the harness. The result is what you see here. There is a light, but no digital readout. When I shinned my headlight on the gauge I could see the digital readout. Thoughts?

If the blue and black tach wires are connected to blue and black harness wires there is no light whatsoever. Keeping these wires connected, when the harness yellow and blue are connected (like the manual stated, previous post) there is a backlight but I loose digital visibility.