gauge electric installation
 

Hello! I have a pressure gauge. It has the possibility to program low pressure alarm, but only stays in memory if it is connected to 12v permanent positive ....
Has anyone made this installation in our car with a start button? not with a starter key.
Can you explain which cable you use for permanent 12v?

Does it have 2 positive connections with one being a constant as you mentioned and a switched so it's display / backlight only comes on when ignition is on ?

Typically any device will state in it's documentation what it's amperage draw is. If your gauge draws very little, you have both constant and switched with ignition 12V leads that are easy to identify and tie into via the stereo harness. Again, it will depend on how much your gauge draws though.

Yes, two positives, and the light only comes on when contacting, but it does not keep the memory ..... they are prosporst gauges, and I have to regulate the low pressure warning every time I turn the car off

Fuse Taps
 

For your constant I would use a piggy back / fuse tap which allows you to tap into power at the fuse box. You will just need to use a multimeter or simple 12 volt electriial tester to determine which fuses have constant power when the ignition is off. You will find several so I would pick one which does not control something crucial for vehicle operation. Perhaps something simple as dome light.

This video should walk you through it. If after viewing it you still do not feel comfortable doing it yourself, search out a shop or friend who understand basic automotive wiring.

[ame="https://www.youtube.com/watch?v=8omZ545Cw1U"]https://www.youtube.com/watch?v=8omZ545Cw1U[/ame]