Rallye Dash Oil Pressure Gauge not working???

[green440duster]

Hi my friend has a 71 Duster with a rallye dash, all of his gauges work except for his oil pressure gauge, the cluster seems fine otherwise and he said that a guy tried to send a signal (not sure if it was voltage or grounding) and the gauge responded. I told him that it might be the sending unit but he only has an aftermarket sending unit. I have never seen a factory rallye 340 oil pressure sending unit, are they different from a modern(78??) unit or should I get him to check something else.
Anyone shine some light on this problem???

Thanks

[68_Val_Sedan]

sounds like ou have your answer ... the sender is bad ... they should be avaiable from napa ...

[Tejas]

STANDARD MOTOR PRODUCTS Part # PS59, $13 from http://www.rockauto.com/

[PureGTS]

  It is easy enough to test the gauge. With the ignition on, running or not, note the position of the guage needle. Then disconnect the wire on the sender and recheck the gauge. If no change, short out the wire to ground and keep it grounded while you or somebody else checks the gauge. The gauge should do something, it's not very fast but you should notice a change. If still no response from the gauge, start checking the wiring from the sender to the gauge and verify that it is the right wire for the gauge (not that that has never happened before).
  You may have to remove the cluster at some point. The pins on the back of the circuit board can come loose too and can cause the same problem. The idea is to isolate the gauge as not being the problem, since it is the biggest pain in the bottom to get, we want to make dead nuts sure that it is OK and the problem is somewhere else.