This request was from a subscriber on another post regarding my HDKCA 10KW Onan throwing a 3-6 code. Currently I'm slowly tracing down problems and replacing items that it could be.
Wanting gauges is an important part of me wanting to see a problem before it becomes one. Dummy lights aren't something I enjoy. I am an airline pilot so seeing gauges work is such a joy. Weird, I know.
Onto the gauge discussion...
Most gauges you will come across are either electrically driven (through a sensor at the engine) sending a signal to the gauge. The hiccup here is that you have to add the sensor to the block for oil pressure and at the thermostat head for water temp.
The other type of gauge would be considered "old school" or analog sending an actual oil pressure through a hollow tube or temperature through a thermocouple to the coolant temp gauge. This style is prohibitively hard to do as my generator slides in and out of the RV and the motion alone would fatigue the analog connectors causing a failure of the gauge.... SO ELECTRIC IT IS!
I bought some electrically driven gauges that came with sensors off amazon. The brand is AutoMeter. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
These work well and while they are alittle small, you'll see why size shouldn't matter too much for our setup.
As you can see in the attached photos I used brass fittings and teflon tape to secure the existing temperature sensor/oil pressure switch to a 'T' fitting that would accept the new sensor for the gauge set. That's a fairly easy thing and the fittings are normal fittings that are not hard to find. **You may be wondering why I said 'Oil Pressure Switch'... The existing oil pressure sensor is actually a switch. Onan has their way that the sensor kills the engine when the switch is not sensing at least (I think) 15 PSI.
Onto more wiring. Every single fitting was soldered. Under no circumstances should you use crimp fittings in any automotive set up... to include stereos, just solder it and heat shrink it. You can't change my mind on this unless you need to hook something up in a pinch.
I used a nice quality 18 gauge braided wire that would withstand 500F and ran it to the front dash where it wouldn't bind with the generator slide (I routed it alongside the 120/240v hookups). You'll need two wires, one for the oil pressure sensor and one wire for the temperature sensor.
Hooking up the gauges is fairly simple. Negative(-) to a good ground (I found an open bus bar near my dash components and used that as my ground) and the power (+) came from the 'generator run' power (not start power). Finding this is simple... Grab a multimeter and test the poles on the back of the generator start/stop switch. Find out which one has 12v when running and 0 when off. This pole would typically run the 'generator on backlight annunication'. This run power would ONLY provide the gauges with 12v when the generator engine is running, no other time would the gauges be active. This would alleviate the confusion as to why the gauges might not be working, etc. I also wired the included backlight to when the generator is running as well. Unfortunately the backlight on the gauges are incandescent making them heat up after some time. I'm sure I'll switch those to LEDs at a later date.
Please check out the pictures. Ask away with the questions. I think this set up has provided data that may seem superfluous, but its good information. I.E. I noticed my oil pressure was hovering around 30PSI, kind of low but I assumed it was a defect because of potentially how I mounted the pressure sensor... Well I checked the oil level, it was slightly above the full line. I siphoned some out and checked the pressure, ~43PSI.
Are the gauges overkill? Maybe. Are they cool? You betcha!