to help visualize it. the pyrometer is just a sensor(k type thermocouple) that threads into a collar that is a little smaller than a dime that is welded either directly on the turbo housing or more commonly on the exhaust right after the turbo. if you have exhaust blankets covering it there might be a hole in it where the sensor or at least the wire sticks out. the 2 wires (one for plus and neg) will run directly from there up through wire tunnels up to the dash where it hooks directly to the gauge (or to a amplifier box right by the gauge) btw, honking the horn should have nothing to do with it unless there is a loose connection at the dash. the pyrometer sensor sticks through a hole in the exhaust (or turbo)
it is a very simple system with only 3-4 parts. 1. the sensor (k type thermocouple) 2. the wires 3. the gauge itself. 4. the amplifier box
so, if honking the horn makes it work, either it is the biggest coincidence in the world or there is a loose connection up front since the horn vibration shouldnt shake anything back at the engine.
possible the gauge itself or amp box is bad, but less likely than a loose connection.
i installed the pyrometer on mine myself. i also have on one my ford powerstroke pickup. very useful if you use it.
on my newell, the instrument panel had a lot of shared ground wires. i actually ran some additional ground wires from the front main dc panel and have used them for some additional grounding.
loose ground wires on the gauges i think are a common problem for our vintage coaches.
but i have to say that honking the horn is a great first try and certainly the easiest. its kinda like hammering on something with your fist. but sounds better. nothing like the sound of a newell air horn. i always do mine in underpasses.
happy troubleshooting
tom
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