jtbartlett wrote:
> Hello group. It's been a while since I've posted but new problems seem
> to crop up. I have installed a trio of aftermarket gauges to monitor
> engine activity out back. Following the manufacturer's instructions has
> been a bit troublesome. Engine is currently not firing (intentionally)
> while I try to test oil pressure gauge. I got the handy oil pressure
> gauge with the idiot light and pressure sensor all-in-one. The Speedo
> lights are wired hot just like the regular idiot light. Generator light
> works just fine. Tested the OP bulb and it lights. Oil pressure Idiot
> light does not light. I am reading 12V at the oil pressure switch out
> back so I thought it was a grounding issue. Ground strap is tight. I
> can make the OP light work by removing it from the sensor in the case
> and grounding it to the alternator nut with alligator clips. What
> gives? If I am pulling 12V from the front of the car why wouldn't the
> OP sensor ground to the case? There is obviously a fundamental element
> I am overlooking so maybe a fresh set of ears can help out. Thanks for
> any help. At this point it IS appreciated.
>
> PS. I do have oil pressure b/c I removed the sensor and cranked the
> engine. It is pushing oil through. Engine was recently re-installed
> but I haven't tried to fire it until I work this bugger out.

Could it be that your ground path from the sensor to the gauge is too
high?
I ask because of the sensor only has a range of a couple of ohms and
the ground resistance is a couple of ohms, it will introduce quite a
bit of error.
Perhaps temporarily try bridging the ground from the sensor to the
gauge to see if it starts working. If so, you may have a grounding
problem somewhere.

Remco