DIY BMW e90 gauge install with fuse box tap

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DIY BMW e90 gauge install with fuse box tap

Post by Jeroen » 28 Aug 2017, 10:13

Hi guys,

I know there are other DIY out there, but i think this write up has some good info that may be helpful that's not so easily found on the net.

Note that my car is a European e91 of 2006, so the fusebox looks like this:


And this is the paper.

As you can see there are several type fuses used in your car. BMW uses at least 3 of them (mini, ATO and maxi).



There are fuse taps on the market, that allow you to parallel link your line with an existing fuse. It's a neat way to work, and does not involve soldering, except for the power line itself. Make sure you get the MINI kind for this project.


Notice the first picture, it shows the tap in action.

On my 2006, i notice that the the mid sized fuses ( ATO fuse) always have power, even after 20 minutes.
The smallest (mini fuse), on the other hand has some on fuse 29 and 30 (top right) that only have power when ignition is on. Ideal for a gauge or other devices that would otherwise potentially drain your battery over night.
Although a boost gauge does not take much, i still want to park the car when i'm on holiday and not worry to drain my battery.

Then i had an issue finding a neat way to get the power and ground (see my location in the first picture) from the passenger's side fuse box to my steering wheel.
I find the easiest way to route the elertical wire, is to remove the dashboard trim. I got the plastic tools for it cheap via ebay, it makes the job very easy.


On the passenger's side, below the fuse box, there are 2 torx screws holding up a kickboard below the glove box. There's also one light connector that will need to be disconnected. Remove this for easy guidance of the electric wires.

On the driver's side there are 3 torx screws that hold up a kickboard above the pedals. If you remove this and disconnect the 2 connectors, then you have acces to the steering wheel, to the dashboard trim and to the fire wall, guiding the boost signal from your diverter valve using a T-connector (cut and insert). I have a blow off valve; it's the same line, linking the valves with the intake for boost pressure.

I have a stiff iron line of about a meter ( 3 feet) to guide the electrical wires and the boost signal thru the fire wall. You may need to pry the firewall to make a hole. It's easiest to go from the inside to the engine bay.

The electrical wire goes from the fuse box, to the right side (behind the right blower fan in the dashboard trim) up and then all across on the bottom to the left side, to the steering wheel. There you go down and behind the steering wheel. The electrical cable can now be taped to the boost signal cable for the gauge.

I've installed the gauge on my steering wheel by making a small hole and then screwing on a hoek eye screw, which is then connected to my pod holding the gauge.

So the electrical wiring is roughly like this:


Hope that helps !

PS: none of these pictures are mine. I didn't mean to infringe any copyright; just wanted to make a post about the details of the electrical wiring.

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