Stuff Needed
One VDO Oil Pressure Gauge*
One VDO Dual Contact Pressure sender*
Spade type electrical connectors
Pliers/ electrical crimps
Adjustable wrench
Long length of wire (about the length of the car)
Electrical tester (screwdriver and crocodile clip type will do)
*Make sure these are matched - ask before you buy.
You can get the gauges from sciroccos & mk1 golfs for a fiver from a
scrapyard.
Time Taken: an hour or 2
Method
Before you start working on car electrics always disconnect the battery
1, Remove the wire attached to the oil pressure sender and remove the sender from the engine using the adjustable wrench. Some oil will escape but don't worry
2, Screw in the new style twin connector sender unit until tight (but don't overtighten).
3, Connect the original warning light wire that you removed from the original sender to the ** terminal on the new sender unit.
4, Run the wire from the sender to the back of the gauge. There are various ways of doing this, but the following, although can be tricky at first is one of the cleanest as there are not wires hanging under the car or near hot parts of the engine.
As you look at the engine bay from the back of the car look in the corners at the top of the engine bay at the ends of the vent panels under the rear window. Here you will see some insulation foam. The method I used was to remove the rear side panel (see door panels how to..)and poke a sharpened, straightened coathanger through the foam with the wire taped to it. If you feel up towards the rear of the window behind the panel you should eventually find the end of the coat hanger and the wire.
The best way of getting the wire through to the front is to lay it under the carpet near the edge. At the base of the front post that holds the door you should find a small hole (not one with a hinge bolt in). Thread the wire through this and pull it through from the boot area.
Wiring Up
6, Connect one end of this wire to the G terminal on the sender unit in the engine bay.
7, Remove any boot carpets etc so that you have clear access to the back of your gauge
Fitting gauges is explained in the Fitting section of Wiring up a VDO Tempeature Dipstick and Gauge
Attach this (using a female spade terminal) to the terminal marked 's' on the back of the gauge as shown in the diagram below.
8, The gauge will also need a positive and a negative connection, plus the lighting to work correctly. Looking at the spade connectors. Beside these you should see some symbols which identify which is connected to where. Firstly you need to identify a positive feed from the fuse box. This must be live only when the ignition is on (otherwise your battery will go flat as the gauge will constantly be on. To find the correct wire, either identify from a wiring diagram which is the wiper motor feed or another suitable connection. To test to see if this is only live when the ignition is on first reconnect the battery. Now taking the electrical tester, connect the crocidile clip to an earth and place the other end on the metal of the wire you want to find out about. If it lights upthe bulb in the tester, you want a different wire.
9, When you have found a suitable wire, turn on the ignition until the warning lights on the speedo come on and then repeat the test with the tester. What you want is a connection that lights the bulb only when the ignition is on. Once you have established this, disconnect the battery again and using an electrical connector, connect it to the positive terminal on the gauge (marked '+').
10, For the negative (middle bottom terminal), there is an earthing cluster towards the middle of the car from the fuse box.
11, To get lighting on the gauge, take a feed from the lighting for the speedo using a piggy back connector or such. You also need to connect the other terminal on the gauge bulb holder to an earth.
Finally
Now you should have a working oil pressure sender and gauge. Reconnect the battery and turn the ignition on until the warning lights come on. Both warning lights should come on as before - the gauge is more of an early warning system than the warning light.
What you need to keep a watch for is low oil pressure and sudden changes in
pressure.