Originally Posted by namba209
If you are measuring between the two connections on the oil pressure transmitter, that's not the way to check it out. It should be either terminal to ground. The oil light switch terminal should read 0 ohms with the engine off and the gauge terminal should read high ohms.  With the engine running, the oil lite switch terminal should read an open and the gauge terminal should read a lot higher and decrease as the rpm goes up, indicating a higher pressure as the rpm increases. Here's the approximate readings of the gauge side of the transmitter taken at the Green instrument panel connector, pin 6 to ground:
HTH.
1 bar = 45 ohms
2 bar = 77 ohms
3 bar = 113 ohms
4 bar = 145 ohms
5 bar = 175 ohms
gauge pegged = 250 ohms.
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. . . I was just rereading this thread and thought I'd correct the "not entirely correct"
gauge readings/sender resistances info based on recent experiences discussed in my "
OP Sender Conundrum" thread.
The VDO OP sender's ohms resistance range is specified as 10-180 ohms, i.e. 10 ohms minimum reads 0 BAR/PSI and 180 ohms maximum reads 5 BAR/80 PSI. ANYTHING outside of the 10-180 ohm reading on the "gauge" wire, i.e. short/zero ohms or open/<180 ohms will cause the OP gauge needle to peg! . . . ask me how I know! . . . this is also why the OP gauge needle "jumps" slightly when you first turn the ignition key "on" . . . current flow through the OP sender's minimum 10 ohm resistance.