Club 80-90 Forums

Just fitted a set of three VDO gauges and with advice from a top man here Mr AXEMAN and a loom from eBay I have then in and looking good... BUT!! .. Oil temp , oil pressure and volts all with illumination. Volts works perfectly, oil temp I don't have a sender for yet and, as I would expect it dosent move, but the oil pressure as soon as the ignition is switched on goes off the scale..... Any ideas??????

Are you using the correct oil pressure sensor with the gauge? Since you are using a VDO gauge you must use a VDO sensor that is compatible with it.

icosahedron wrote:Are you using the correct oil pressure sensor with the gauge? Since you are using a VDO gauge you must use a VDO sensor that is compatible with it.

Well I guess so, it's the sender that came with the gauges and its a vdo one twin tag "g" and "wk"..???

As its not screwed into the metal of the engine, does the sender need to be earthed? I had to do this with a water temp sender I fitted into one of the coolant hoses

Good, can you explain how you wired it.

I bought a hose joiner with a tapping for the sender, it also had a tapping for an earth post. I didn't bother with the earth and the gauge didn't work. I then fitted a earth wire onto the joiner and onto a earth point in the engine bay (I used the one under the alternator[diesel] ) gauge then worked fine

Right instructions as follows that came with the loom
Connect red wires to pos term on all 3 gauge( a line of 3)
Connect blue to neg term on batt gauge and earth on press and temp gauge(3in line)
Red and blue need to connect to switched power red to pos and blue to neg
Now connect yellow and green to "g" on remaining terms on gauges

Now when I ign on I get almost 12v to the pressure gauge and needle goes off scale??
I also put an earth tag between sender and t- piece to existing earth tag in the engine bay
I am left with the "wk" terminal on the sender with no home?
Makes no diff if sender is connected or not to needle movement
Does this make sence??

KINGPRAWN wrote:Right instructions as follows that came with the loom
Connect red wires to pos term on all 3 gauge( a line of 3)
Connect blue to neg term on batt gauge and earth on press and temp gauge(3in line)
Red and blue need to connect to switched power red to pos and blue to neg
Now connect yellow and green to "g" on remaining terms on gauges

Now when I ign on I get almost 12v to the pressure gauge and needle goes off scale??
I also put an earth tag between sender and t- piece to existing earth tag in the engine bay
I am left with the "wk" terminal on the sender with no home?
Makes no diff if sender is connected or not to needle movement
Does this make sence??

Just found on a samba page that the "wk" connection goes to the idiot light... Nice!
Found that if I earth the yellow wire( "g") tag the needle drops to zero... But on start up the gauge does nothing!!!
Getting near the end of my patience now

It would make my day if someone could tell that the gauge is duff!!!

Everything seems fine except that I do not get the following:

KINGPRAWN wrote:Now connect yellow and green to "g" on remaining terms on gauges

"g" on gauge should connect to "g" on sender. A low oil pressure switch is built into the sender and connects to the "wk" terminal. If you moved the original oil pressure switch to the t-piece then ignore it since you will be using the original.

Thanks for your input... Getting desperate now!
I moved the sender between the pushrods and relocated to the t-piece and connected as normal.
Have a wire from the "g" tag on the pressure gauge back to "g" on the sender and a wire from "wk" to the original sender in the t-piece.... Yes???
But why does it go off the scale regardless of sender connected or not. As soon as its powered off it goes... Ahhhh!!!

One other thing, when the oil is cold the pressure will be high. If you have a 5 bar gauge it might worth connecting the gauge after the engine has warmed up and the pressure has come down. This will at least proof that the system is working.

Thanks for that theory which does make sence but its such a violent sweep that goes right off the scale!... Problem with something somewhere!

If you are using the original oil pressure switch then leave the "wk" terminal disconnected. You can however use either but I would stick with the original.

You say that the needle drops when you connect "g" to ground, but when the ignition is on, it goes off scale. Does seem as if the sender might be faulty as it should have low electrical resistance at low pressure. Do you have an ohmmeter to check this?

Yes I do.. But.. I don't really know hoe to use it. Can you tell me what to switch the dial setting to and what trading I should see???

Switch the meter to R or the "omega" sign. The scale is not important for a simple test. Now connect the two probes to the meter and short them together. You should get a reading on the meter. A digital meter will display something close to zero or on an analogue meter the needle will move over to the right. Now connect one probe to the body of the oil pressure sender and the other to the "g" terminal. You are supposed to see something similar on the display. If the display does not indicate a low reading or needle stays on the left then the sender is faulty.