B4 90: Adding Optional Auxiliary Gauges
The Aux. gauges are a great upgrade for those wanting instrumentation to monitor your car's battery power (Volt meter), Oil pressure and Oil temperature gauge. With a little bit of wiring, these can be added to any non-equipped B3 or B4 with ease.
3 Auxiliary Gauges with Housing and Wiring harness (from a type 89 or B4)
Oil Pressure Sender (Part# 035 919 561)
Various hardware bits
The first thing you'll need to do is remove your center consoles.
Remove the rear ashtray to expose the bolt and remove it. Next, remove the cover located near the tip of the emergency brake to expose an 8mm bolt. With these removed, raise your e-brake and pull your rear center console up and set aside.
Remove shift knob.
The front center console is free to be pulled back and up in order to remove it.
Now, you will need to remove the front ashtray. There are two 8mm bolts located under the ashtray. Next, remove the manual dials for the air/heating system (pull really hard). Insert a flat screwdriver (or similar) and raise the wooden trim from around the dials. If you have automatic climate control, simply remove the wood trim. This will expose two remaining Philips screws holding onto the ashtray.
If you did not receive the center console with your gauges, you will have to drill out 4 holes out of your existing console to mount the gauge pod.
The OEM gauges use two wiring harnesses to attach the wiring. Both of these will need to be snipped off in order to splice the wires with your car.
Here's the color coding you'll need:
GREY W/ BLUE STRIPE (2 WIRES TOGETHER) - ILLUMINATION LEAD
GREY W/ BROWN STRIPE - POWER TO GAUGES
SOLID BROWN - GROUND
BLACK W/ BLUE STRIPE - 12v SWITCHED (IGNITION) FOR VOLTMETER
RED W/ BLUE STRIPE - CIGARETTE LIGHTER PLUG
Snip off the black plug from the aux. gauge and match the wires (color code) with the wires snipped from the yellow connector plug from your car
These wires are for the Oil Pressure and Oil Temperature gauges.
Your Oil Temperature gauge should work just by connecting the wire, but in order for the Oil Pressure gauge to function properly you will likely need to buy an Oil Pressure Sender (until then, it will max out the reading).
Tuck in all the wiring, and re-assemble everything in reverse order.
Oil Pressure Sender Location: