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Do some oil pressure senders work backwards?
the_fbi - 22/12/06 at 05:13 PM

Just changed my Autogauge Oil Pressure gauge for a VDO one, as the Westfield loom already has the connect for that in place and it looks neater.

Before, with the Autogauge one (and the autogauge sender) the gauge would read max without the sender wire connected and 0 with it earthed.

Now the sender wire is connected to the sender and the VDO gauge is in, the gauge is reading max. This appears to be the reverse of how the Autogauge gauge would have worked.

Just tried to start the car for the first time and whilst the battery has enough power for lights, dash, etc its not got enough to turn the engine over, so I'm waiting for a few hours charge before seeing if the gauge drops with the engine running.

I know that there are fuel senders which work both ways (some 0 Ohm at emtpy some 0 Ohm at full) anybody know what a VAG oil pressure sender does?

ta
Chris

Peter M - 22/12/06 at 09:32 PM

Make sure that the VDO sender is earthing to the block by its threads as if not then the gauge gives full scale deflection . This can happen if you have put some ptfe tape on the sender threads.

the_fbi - 22/12/06 at 09:53 PM

quote:
Originally posted by Peter M
Make sure that the VDO sender is earthing to the block by its threads as if not then the gauge gives full scale deflection . This can happen if you have put some ptfe tape on the sender threads.

Thats a good point actually, as the sender is now remotely mounted on the filter head on a sandwich plate on an ally bracket rivited to the chassis with silicone for extra sealing, so possibly not too well earthed!

I'll have to see if I can tap one of the blanking plugs on the sandwich plate for a earth strap.

ta!

the_fbi - 23/12/06 at 11:06 AM

quote:
Originally posted by Peter M
Make sure that the VDO sender is earthing to the block by its threads as if not then the gauge gives full scale deflection . This can happen if you have put some ptfe tape on the sender threads.

Great.....

Rmote filter head is earthed fine, filter itself is earthed fine, but the sandwich plate in the middle, is insulated by a O-ring either side, so its naturally not earthed.

Arse, but at least you pointed me to the problem. So it will be a case of drilling/tapping a stud into one of the blanking plugs. Not too terrible.

Thanks!