VDO Electric oil pressure guage?

[Carledo]

Having completed the new and more traditional dash for the Carledo, I have run into a little problem that has confused me!

I have successfully made the rev counter and temp guages cross the Triumph/Vauxhall divide but the oil pressure guage is defying my best efforts! The car was originally fitted with the dash from a Nova SR which has an integral electric OPG triggered by an engine mounted combined guage/light sender. This worked perfectly! The sender is marked VDO and 0-5bar.

Now I had in stock, a single 2" VDO OPG with a scale from 0-10bar and tried it on the "why not" basis, but it jumps to full scale as soon as the ignition is switched on! there are 3 tags on the back, marked +, -, and S which I fed, earthed and connected to the signal lead respectively. Since this clearly didn't work, I decided the mismatched guage was at fault and bought a VDO 0-5bar scaled guage from an ebay seller in Latvia (of all places, but it was that or Poland and the Polish one was identical but £10 more!) There were NO instructions in the box!

Unfortunately this (new and expensive) one behaves in exactly the same way!

So come on sparkies, what am I doing wrong? I've checked the (printed) circuitry on the Nova dash and though it does have a built in voltage stabiliser for the fuel and temp guages, the OPG doesn't appear to run through it! It's unresponsive to swapping wires around, and leaving the sender lead off with + and - correct still maxes it out. And now i'm out of ideas!

Can anyone help me? I feel naked without my OPG!

Steve

[Galileo]

VDO gauges go full deflection with a floating signal, earth the signal pin and it should go to zero. Measure the resistance from your sender, at zero bar (PSI) it will probably be 5-10 ohm and increase with oil pressure. If the resistance is fine, must be the wiring between the sender and gauge by elimination.

Hope that helps.

[Carledo]

Thanks Rafe, I now have a working oil pressure guage, in fact, I have 2! The 0-10 bar guage reads in exactly the same position as the 0-5 bar one, ie double what is correct. (with the 0-5 bar sender)

Turns out, i'd got confused and mismatched the Rists plugs pins from the dash to the main loom for the OPG signal lead. Once I knew what I was looking for (should have been obvious, DOH!) finding the fault was easy!

So can I interest anyone in a genuine VDO 0-10bar electric oil pressure guage, test use only, circa £40+ on ebay, £20 + postage (but you'll need a 0-10 bar sender) Upper quadrant style and similar font to Dolomite instruments, black bezel and lights up green like later Sprints do.




Steve