engine and drivetrain Extra gauges - voltage sources?

[jjbunn]

I am adding three VDO gauges in my centre console: Oil Pressure 0-150psi, Volts and Vacuum.

Others have certainly done this before, but I need some specific advice which I can't find via Search:

1) For the Voltmeter, it should measure battery voltage (not regulated voltage) - where is the best place to T into a B+ supply behind the dash - the light switch, or the cigar lighter?

2) For the Oil Pressure, it will need regulated voltage - where is the best place to get that? I think regulated voltage is on a Blue wire entering the console, and also on the remote equipment socket in the engine compartment - neither very convenient.

3) The gauge lamps should come on with the other instrument lights and dim with the dimmer control on the main cluster - where is a convenient connection for the gauge lights?

Thanks!

[BillWilliams]

3) There is a connector under the dash, sometimes it is taped to another wire. I believe it has a blue or blue gray wire leading into it. This is the connector used by automatics to light the lighted surround on the gear selector.

Good place to get dimmable power for your gauges.

[sirius815]

Overall - if the car is running - all voltage will be regulated as the alternator + battery form 1 system, however I would connect as close to the battery as possible - which would mean at roughly the ignition switch, or you could splice in at the fuse panel - doesn't really matter. Also, if I remember right, the Voltage gauge only has the one set of leads + and - (well that and the bulb). You can get power for the oil psi gauge there as well.

Isn't 0-150 psi a bit wide range - might 0-100psi be better? I only as because in my e36, oil pressure is rarely ever above 60psi (possibly due to sensor location/connection). If the oil system never sees about ~80ish PSI, the 0-100psi sender+gauge would give you the best resolution.

@Bill Williams - good to know!

[jjbunn]

3) There is a connector under the dash, sometimes it is taped to another wire. I believe it has a blue or blue gray wire leading into it. This is the connector used by automatics to light the lighted surround on the gear selector.

Good place to get dimmable power for your gauges.

Brilliant! I'll take a look for that. Thanks, Bill.

[jjbunn]

Overall - if the car is running - all voltage will be regulated as the alternator + battery form 1 system, however I would connect as close to the battery as possible - which would mean at roughly the ignition switch, or you could splice in at the fuse panel - doesn't really matter. Also, if I remember right, the Voltage gauge only has the one set of leads + and - (well that and the bulb). You can get power for the oil psi gauge there as well.

Isn't 0-150 psi a bit wide range - might 0-100psi be better? I only as because in my e36, oil pressure is rarely ever above 60psi (possibly due to sensor location/connection). If the oil system never sees about ~80ish PSI, the 0-100psi sender+gauge would give you the best resolution.

@Bill Williams - good to know!

Yes, good suggestions, thanks - I'll take B+ off the ignition wire.

I think 150psi is the recommended range, from reading around it can get up there in some situations.

[tim385]

Yep 150 psi is good , when cold mine runs up to 120psi.

[sirius815]

Thanks for the confirmation.