58 Oil Pressure sending unit wiring circuit

[David King (kz78hy)]

My oil pressure light has started coming on during my reassembly of the car this summer.  On the Brougham, I have 2 sending units, one is a gauge and the other is a low pressure light.  I have good oil pressure on the gauge and the light came on and remained on while sorting out the other sending unit.

The light stays lit whether it is plugged to the sender or not and the engine running.  According to the manual, I think I have shorted the circuit somewhere and am looking to confirm.  With a  multimeter, I have continuity through the circuit with it connected to ground and the other lead attached to the unplugged terminal that connects to the sender.   The battery is disconnected.

When the lamp is removed from the socket in the I/P cluster, the continuity is broken.  So far, I can't find a obvious damage spot where I broke into the wire and tracing the harness is going to be a very hard thing to do, so I want to make sure this the problem before attempting.

Thanks for any ideas.

David

[Kurt Kjelgaard]

Hi,

Try this - it might work..
It should be possible to find the point where the wire is shorted as long as
you can follow the wire with no need to open the insulation.
Run a compass needle (borrow somebodys boyscout compass) along the wire/harness
from the sender - when you reach the point where the wire is shorted an indication
on the needle should show up. The wire carrying a current from this point
creates a magnetic field, on which the compass needle should act.
It's worth a try.

Kurt

[Kurt Kjelgaard]

Ooops - forgot to say that there must be power on the wire to make this work