Analogue Gauge Conversion

Converting the LED type Volt and Oil TemperatureGauges and moving Differential lock switch on a Coupe Quattro

This file provided by: Iain Atkinson, on 5th December 1999.
Copyright conditions, copy as you like but please give credit where it's due.
You may reach me at: iain.atkinson@etl.ericsson.se
I have a web site related to both my Coupe and a friends URQ at http://www.geocities.com/MotorCity/Show/7106/

My reasons for wanting to do this conversion are: that I had always liked the 3 extra gauges that came with the Coupe GT, these being a Voltmeter, Oil Temperature and the all important Oil Pressure. When I got my Coupe Quattro it just had the standard LED panel giving you the two position Differential lock switch and LED readouts for volts and oil temperature (erratic at the best of times), my main requirement apart from asthetics, was the addition of an oil temperature gauge.

The Parts needed are:

• The 3 gauges along with the as much of the wiring loom as possible and the plastic holder for them
• Dual oil temp/pressure sender gauge part no 035 919 561A
• Plastic tube to extend the vacuum lines to the moved switch location and cable ties to secure the hose
• As for tools, well you just need basic screwdrivers and stuff like that, nothing special needed here.

Start by first of all installing the oil sender unit. The correct location for this is on the right hand side of the block inline with no 2 cylinder just below the coolant pipe that runs horizontaly along the block. The sender unit you are replacing should be white in colour, I got mine out by bending down the male connector and getting a socket onto it. Then screw in the new dual sender and tighten with a 17mm open ended spanner, make sure you use the copper crush washer. Connect the old wire to the "WK" terminal, the other terminal needs the Blue / White wire connected to it which should already be close by in the loom, if not then you will need to run a wire directly from this to oil pressure gauge inside the car.

Next, working inside the car, remove the centre console, shift boot, gear knob and the panel with the LEDS and differential lock and unscrew the differential lock knob. Before removing the differential lock make a note of where each vacuum line goes onto the grey rubber block on the back of the switch, this is VITAL for later on. Fortunately if you have the wiring loom that comes with the gauges it's just a case of matching up the wires so that you have an earth, positive supply, dash lights and then the correct supply to to the oil Temperatureand oil pressure gauges the voltmeter works off the earth and positive supply as it is a common one that runs all three gauges. You may have to dig around for blue/white wire from the sender for the oil pressure gauge, I found mine in a two pin plug with only one plug used (for the oil temperature, green and black I think it was). Next thing to do is to check that all the gauges work and that they light up.

That's the easy bit - now onto what I found is the hard part, moving the differential lock switch and vacuum lines.

I decided that to try and keep everything as factory looking as possible I would try and integrate the switch as close to it's original position as possible. Going back to the centre console, unscrew the panel that holds the electric window switches and cigar lighter, remove both switches and the lighter, now carefully file down the back of where the lighter used to be until you can put the Differential lock switch in its place and push home the knob until just engages on the switch itself or you can feel a slight click.

Now remove the knob and switch and mark a point in the centre of where the electric window switches are, now drill a pilot hole and then drill out/file the hole until the lighter is a nice snug fit. Going back to the Differential lock switch and knob you now need to secure this in it's correct position which is 90 degrees to the piece of plastic it is being mounted in, the best way I found to secure it was using 3 self tapping screws and drill with a small drill through the remaining lighter surround plastic at the back of the panel.

Now fit the lighter and window switches back in and refit to the centre console.

Ok, we are on the home straight now! Loosely put the centre console back so you can get to the vacuum lines on the tranny tunnel. Then measure out a sufficient length of your washer bottle pipe so that you can connect up on the back of the switch and secure each pipe with a cable tie (hopefully you will have the piece of paper with the correct order on it, and remember that the switch is now turned through 90 degrees). Might be a good idea to test fit the console back in place and check to make sure the diffs do actually lock. This where I lost most time and came up with using the washer bottle hose, as it's reasonably flexible along with the cable ties to hold things together.

Now it's time to fit the LEDS, all credit for their manufacture goes to my brother in law Nev, another Audi nut who is more gifted than I with electronics. I decided to mount them just above the headlight switch, the green one is for the centre Differential and the red one is for the rear. I needed to drill a couple of 3mm holes and secure with a dab of glue. You will also need a switched 12v supply to them as well, pretty cool huh?

It's now time to put everything back together as carefully as possible, especially with the vacuum lines as they are pretty easy to kink or pull off, it's a real pain to get everything back together, only to find something doesn't work, so keep making sure it's all ok as you put it back.

The correct order for the vacuum pipes is: TOP of the rubber block Blue ,White (I think from memory this goes in the centre),Yellow. BOTTOM of the block Green and Red.

In my opinion it's well worth the effort to do this modification, sometimes when extra gauges are fitted to cars they look like what they are, an after thought, this way it still retains it's original look, and they do look good all lit up at night.