Switched power supply for aftermarket gauges

[Oldchevyguy]

Ok, so I'm using aftermarket electric oil pressure and water temperature gauges. Found a spot for them right of the ignition switch. Normally I would grab power from the switch, but I'm not sure that will work on this car. Does anyone know if the power port (cigar lighter) is switched power, or hot all the time? Any other ideas?

 

[Ross]

My car had 2 cigar lighters. One has constant power, I am not sure about the other one. I did find a heavy wire on the BCM that was switched to run my wideband O2 sensor.

 

[Karter2026]

Ok, so I'm using aftermarket electric oil pressure and water temperature gauges. Found a spot for them right of the ignition switch. Normally I would grab power from the switch, but I'm not sure that will work on this car. Does anyone know if the power port (cigar lighter) is switched power, or hot all the time? Any other ideas?

Both of mine are hot at all times.

Best idea I saw so far I kept a few keyed hots from radio and wipers when I did my harness but used them up. I may follow this since I have other things I want to run that should be keyed hot.

 

[Oldchevyguy]

My car had 2 cigar lighters. One has constant power, I am not sure about the other one. I did find a heavy wire on the BCM that was switched to run my wideband O2 sensor.

Could you tell me how to identify this "heavy wire on the BCM"? I would like to use it also. Wire color ( probably pink), pin location, or where it goes would be appreciated.

 

[JSATX]

Just make a dedicated fused power block for all the accessories you’ll be glad you did. Takes barely an hour or two and makes life a lot easier.

 

[Ross]

Could you tell me how to identify this "heavy wire on the BCM"? I would like to use it also. Wire color ( probably pink), pin location, or where it goes would be appreciated.

My wire to the wideband goes to the back of the BCM, the white connector, C4 I believe it is called. I used a meter to probe the unused wires until I found an ignition switched one. I didn't take my car apart, so I'm not exactly sure which wire I used.

 

[Oldchevyguy]

Just make a dedicated fused power block for all the accessories you’ll be glad you did. Takes barely an hour or two and makes life a lot easier.

If I did that, it would be hot all the time. I do not want my gauges to be on key off.

I found a wire I ran for the stereo I may put in in the future. Its switched power. Problem solved! I will connect gauge lights to the brown parking light wire running to the left mirror.
Thanks to all that helped!

 

[bradr]

One of the best spots to grab Ignition power is the abandon ABS circuits found in the diagram below (BCM X5 pin B2). This will have power in key positions 2 and 3 (Run and Start), is a dedicated 10a circuit and is perfect for instrumentation.

For non-critical components, Accessory power is a better choice (IE. USB Ports, stereo, etc). This will provide power in key positions 1 and 2 (ACC and RUN). This will provided a dedicated 30a and 15a circuit. Way more than anyone will ever use.

 

[Karter2026]

If I did that, it would be hot all the time. I do not want my gauges to be on key off.

No it would not if you set it up the way it is described in the post that I linked. If it is set up that way It will give you 6 separate keyed hot accessory ports. You need one keyed hot to trigger the relay . I am doing this same thing that JSATX did. I want to install a radio some gauges and probably some switched fans for my heat exchanger. I can fuse each one at the fuse box and be able too keep the wiring neat when done.

 

[Lonny]

If you need a lot of switched power I think the big brown wire that went from the gray BCM plug to the
A/C heater fan comes on with the key.
On the red BCM plug D7 is key on power. Pink wires.