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General => The garage => Topic started by: GolfsRus on 05 March 2011, 22:49
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Wire colors on the VDO gauge harness are:
Blue / black - Switched 12V (terminal 15)
Brown: Earth (terminal 31)
Green / black - Oil temperature signal
Light blue / white - Oil pressure signal
Grey / blue - Illumination
Red / blue - cigarrette lighter feed (not needed)
Cut off the white plug, not required on a Golf, some also have a lighting relay fitted, you can cut this out it 's not needed.
Locate a switched 12V supply, and connect the blue / black wire.
Found mine at the ignition switch and spliced in.
Locate a good earth, and connect the brown wire.
I found a good spade connection at the back of the fuse box.
The voltmeter is now operational, as are the oil pressure and temperature gauges, though the latter 2 need a signal
For the oil temperature gauge, extend the green / black wire from the back of the gauge (G) and locate through to the engine bay, there's a handy grommet just to the right of the fuse box. Connect the extended green / black wire to the extra temp sender (you will need to buy a second sender unit) that you will fit to the T Piece.
Under the bonnet, you will see you already have a green / black wire fitted to a temp sender on top of the filter housing ,this operates the MFA temp display, leave this in place and you can have two temperature readouts.
On the oil filter housing, remove the oil pressure sender that is originally fitted. In it's place screw in the T Piece with the oil temp sender fitted. Connect the green / black wire to the sender. The oil temperature gauge is now operational.
Now for the oil pressure gauge. Working inside the car, extend the blue / white wire from the gauge (G) and route through the same bulkhead grommet as the green / black wire. Run the wire through into the engine bay. Take care when fitting, that it is not trapped, or likely to catch on any moving parts.
Now fit your replacement 5 Bar (80psi 2 PIN type) sender into the other opening in the T Piece and attach the blue white wire to one of the 2 pins of the sender, and the original pressure sender blue / white wire to the other pin. Note if you have a 0.3 +- .15 bar (find on the spanner flats) fit it in the low pressure sender slot at the side of the head. If the spanner flats state 1.8 +- .15 bar fit it in the high pressure slot on the oil filter housing.
Care is required here - the 2 terminals are different. One is marked with a blue paint mark. This one MUST be connected to the extended blue / white wire, fitted with a suitable female spade connector. The remaining terminal MUST be connected to the original connector, which operates the oil warning lamp and buzzer.
Back inside the car, locate the instrument illumination feed behind your dash - easiest way is to tap into the grey / blue feed for your heater panel illumination. Splice the grey / blue wire from your gauges to this feed, an extension may be required.
Now, switch on your side lamps, gauges should illuminate and you will also have the dimmer adjustment working with the gauges.
Switch on the ignition - voltmeter should read at least battery voltage, and oil pressure and temperature gauges should JUST move up from their rest positions.
Start the engine, voltmeter should read approx. 13/14 volts with all consumables switched off. On a cold engine, oil pressure should be at least 4.5 - 5 bar at idle.
Oil temperature will rise slowly as the car is driven. If the car is driven hard, temperature could be anything between 70 and 90 degrees cels. On a very hot day, with sustained high rpm, it could rise as high as 120 degrees. Ideally, you want to back off at this point, till the temperature drops.
NEVER let the oil hit 130 degrees!! If it regularly reaches the 120 degree mark, you may want to invest in an oil cooler.
It is normal for the oil pressure to drop as temperature rises, at idle with the oil at 90 degrees, a pressure reading of 1.3 - 2 bar isn't uncommon. It should rise to 4.5 bar minimum above 2,500rpm on a healthy engine, 5 is ideal. An engine with a lot of hard miles under it's belt may only rise to 4 bar above 2,500rpm, but no cause for alarm.
This is for Golf mk1 fitting, Golf 2 & 3 similar, though location of oil pressure / oil temperature may vary, depending on engine type. Golf 2 & 3 may NOT have the signal wire for oil temp (green with black trace) in place.
If car is a GTI with OE MFA fitted, it WILL have the oil temperature signal wire in place, but do NOT use the sensor as a common for the MFA oil temperature, as well as the VDO gauge. It will cause the MFA to read not only oil temperature, but also the internal resistance of the VDO gauge. (Analogue gauges have a higher impedance).
In such cases, either find another blank on the oil filter housing, or on the cylinder head for the extra sensor to provide the signal to the VDO. Or, alternatively, use a splitter available from any hydraulic coupling centre with the appropriate thread to fit the original MFA location, with the 2 internal threads suitable for the OE VDO and MFA sensors.
This is the way I have just fitted a set of gauges and they are up and working fine. I used a T Piece to fit the oil pressure sender and the extra oil temperature sender to the top of the filter housing unit.
I now still have the MFA temp and the new gauge reading oil temp also.
Thanks go to Rubjonny for his help, hope this is useful for future fitments.