Oil presure guage wiggled then pegged to 5

[jbirkett]

My oil pressure guage has always wiggled but at idle when warmed up is between 2 and 3, during eceleration and at 3k+ rpm is 4 or more. Today on the way home it wiggled a little and then pegged at 5 and stayed there. When I turn the ignition off it drops down to 0 and when I start the car it peggs to 5 again. There is not too much oil and the oil level guage is where it normally is after warmed up, almost full. I checked the oil with the stick and it is normal. Might be the sending unit. Any advice on how to check the unit?
Thanks.
John

[BReyes]

Did you check the wires are tight?

[jbirkett]

Yup, first thing I checked. One was a little loose so I crimped it up and the guage still was pegged. I pulled the guage out and removed all the wires, there were several in the same general area. When I removed one, don't know the contact number, the guage dropped to 0, when I pulled another the guage dropped to about 3 or so. I'm thinking sending unit, but wanted to look further before going for broke and buying a new sender.
Thanks,
John

[Early_S_Man]

John,

Try grounding the sender wire with the ignition switch on ... it should drop to zero unless there is a problem connection at the 14-pin connector, or maybe the sender wire has fractured internally an inch or so 'upstream' back towards the gauge! Vibration has been known to break that sender wire ... you could try testing for end-to-end continuity with a multimeter and LONG set of test leads.

[jbirkett]

Thanks for the help Warren. I should have known that. I grounded the wire and turned the ignition on and bingo, the needle pegged to 0.
Thanks again,
John

[JTL]

I just went through this with mt -84 targa. The gauge pegged as soon as the ignition was turned on. Gauge and wire checked out and so the sender was the only other possibility. Ordered a new sender from Vertex and now the gauge works ok.

Rgds, jt