TheSamba.com :: View topic - VDO Oil Pressure Sending Unit

Tue Feb 26, 2013 10:38 pm

My Oil Pressure gauge quit working tonight. When I turn on the ignition the gauge maxes out immediately. I checked all my connections. My ground is good, my ignition wire is good, the wire to the sending unit has been "suspect" for a while so I ran a new wire. Still maxes out...

I double checked where terminals. WK to the idiot light, G to the gauge.

So I did some research and found this post:

http://www.thesamba.com/vw/forum/viewtopic.php?t=420714

On the next to last comment "Dale M." recommended a test. He said to remove the wire connected to the G terminal and ground it to see if the gauge goes to 0. It did. That indicates a bad sending unit. (Before anyone asks, there is no teflon on the threads. It was working.)

So I did some more research, and found this:

http://www.busconversions.com/bbs/index.php?action=printpage;topic=1975.0

This is supported by a lot of other posts. I did the ohm test. Positive to the G terminal (with the wire to the gauge removed), and the negative a ground. 0 ohms. To me, this indicates the sending unit is dead.

Before I spend $50 - $60 on a replacement...

Did I miss anything? Is there a different test I should perform?

Thanks!

Wed Feb 27, 2013 8:26 am

More and more parts are shit out of the box.I just bought one of those senders and have had one go bad in the past. If one does not put teflon on the threads how will it seal? Any sealant will affect ground through the body and these are not cheap for the quality presented.In other words good money for a so so part at best.

Wed Feb 27, 2013 9:01 am

ManFromNapa wrote: My Oil Pressure gauge quit working tonight. When I turn on the ignition the gauge maxes out immediately. I checked all my connections. My ground is good, my ignition wire is good, the wire to the sending unit has been "suspect" for a while so I ran a new wire. Still maxes out...

I double checked where terminals. WK to the idiot light, G to the gauge.

So I did some research and found this post:

http://www.thesamba.com/vw/forum/viewtopic.php?t=420714

On the next to last comment "Dale M." recommended a test. He said to remove the wire connected to the G terminal and ground it to see if the gauge goes to 0. It did. That indicates a bad sending unit. (Before anyone asks, there is no teflon on the threads. It was working.)

So I did some more research, and found this:

http://www.busconversions.com/bbs/index.php?action=printpage;topic=1975.0

This is supported by a lot of other posts. I did the ohm test. Positive to the G terminal (with the wire to the gauge removed), and the negative a ground. 0 ohms. To me, this indicates the sending unit is dead.

Before I spend $50 - $60 on a replacement...

Did I miss anything? Is there a different test I should perform?

Thanks!

NO ... Doing OHM test on sender and it indicates 0 (zero) ohms during test proves sender has continuity..... Its telling you you have zero oil pressure just like when you test gauge by grounding wire to actual gauge.... You need to apply pressure to sender and see if ohm value increases (cobble up some low pressure air - some fittings and bicycle pump) .....

IF at any point OHM meter reading goes INFINITE then you have open circuit in sender.... Any ohm reading on sender proves you have valid circuit in sender... "Open" in sender or a "open" in wire will cause dash meter to go full scale.... Also ohm meter will show infinite across sender if sender is at fault....

Dale

Wed Feb 27, 2013 9:24 am

Sorry.. I should have said the ohm meter doesn't register anything. I shouldn't have said 0. So that means it is dead.

I will push, pull, etc on it to see if that changes the reading. I will also do a continuity test.

Time to replace it....

Wed Feb 27, 2013 10:22 am

I've had two of the dual post VDO senders fail on the gauge side. For whatever reason the idiot light side has remained functional. Not that this assists in testing it, but it was better to at least have the light for a few days, than nothing at all.

Wed Feb 27, 2013 10:33 am

ManFromNapa wrote: Sorry.. I should have said the ohm meter doesn't register anything. I shouldn't have said 0. So that means it is dead.

I will push, pull, etc on it to see if that changes the reading. I will also do a continuity test.

Time to replace it....

Yes if you have infinite reading on meter..... One has to be a bit careful of terminology sometimes as the misuse of a term can mean a completely different thing for those trying to interpret and help.... BUT no harm no foul....

Dale

Thu Feb 28, 2013 10:00 pm

Just to close this out, it WAS the sending unit. Replaced it today and everything works. Thanks everyone!