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5 bar oil pressure gauge wiring

VB242

I.M. Weasel
Joined
Sep 21, 2011
Location
Driving the No Malarkey Bus
I know there was just a thread about this but I can't find it. I have power going to the gauge, when I hook up the one terminal on the sender the gauge jumps a little then sits on 0 psi. If I put it on the other terminal it pegs out below 0, could I have the power reversed? I got the gauge and sender from pick and pull so I don't know if the wiring is factory. I have + going to blue/ red wire and - to the black wire and green coming from the gauge terminal.
 
OE 52mm gauge?
Looking at the back of the gauge:
-12v to the bottom spade terminal
-ground to the side spade terminal
-sender connection to the top spade terminal

How is your sender connected at the engine? Does it have a good ground to the block (no sealant on threads)?

Also FWIW, the 5 bar gauge I have needs a tap or two with my finger to "wake up" when the car is first started.
 
They also make different sensors for different ranges, make sure you got the right PN

I got both parts from a junkyard car, it's definitely a gauge sending unit, it's got the G and W terminals. No chance to mess with it today had to get a free warranty battery from Walmart for the 780 and also put some a/c repair in.
 
Wiring appears correct, the letter markings on the sender are hidden by the heater pipe. When I put it on one terminal i get 0psi when I put it on the other I get negative psi. Maybe it didn't work for the junkyard car either. When I put it to KP2 the needle jumps up to 0 from resting.
 
They also make different sensors for different ranges, make sure you got the right PN

I know they have a 3 bar, 5 bar (80psi-ish), and a 100psi one. With a couple versions of each with different resistance ranges.

All of them should though produce some activity on the gauge even if the gauge/sender combination is wrong.

Have you got some resistors on hand to test the gauge with? The sender is really just a variable resistor between the gauge and ground (the engine).
 
G should be to the gauge (sending unit portion) and W should be for the warning light (switch). I'm sure you could find a chart of resistance values vs pressure and check between G and ground, if its within spec its probably the gauge.
 
You need to remove the sender and check the part number. It might have the wrong sender.

Some of the 2 terminal VDO senders have a floating ground. They look like the sender for a gauge and a light but one terminal is for ground, not a light.
 
You need to remove the sender and check the part number. It might have the wrong sender.

Some of the 2 terminal VDO senders have a floating ground. They look like the sender for a gauge and a light but one terminal is for ground, not a light.

Couldn't you still check for ground engine off/on at W to see if it's for a warning light or ground input?

Although I wouldn't think a floating ground sending unit would be able to peg the gauge with only one connection
 
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OP says he can't read the letters on the terminals but the gauge sits at 0 connected one way and it pegs below 0 when switched to the other terminal.
 
it's got the G and W terminals.

the letter markings on the sender are hidden by the heater pipe.

Ah I see, I only read the flip, not the flop.

Id'e still expect (correct me if I'm wrong, working off the diagram never used one) that a floating ground sending unit wouldn't move the gauge at all without a ground hookup as it's just an open circuit without it.
 
I think you're right but electricity will do weird things when it can't find a path to ground.

I think the sender may be faulty. It shouldn't be too hard to test with a DVOM.
 
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John, I still have the VDO gauge and sender I got from you. If you need them I will mail.

G should be to the gauge (sending unit portion) and W should be for the warning light (switch). I'm sure you could find a chart of resistance values vs pressure and check between G and ground, if its within spec its probably the gauge.

I did that with this one, used an air pressure regulator to apply pressure, measured resistance.
Not sure I still have it but it was easy to do.
 
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