Water Pump Troubleshooting

Tech- Never Assume….

A quick post this week (only a day late!). Yesterday I made one of the basic mistakes in troubleshooting- not knowing how the system was supposed to work in the first place. While it only cost me about 20 minutes (of unbillable time), it could have been worse, and again taught me a valuable lesson.

I was working on a water pump that wouldn’t run- seems simple enough. Found the pump, unhooked the hot lead and found 12 volts on it (with a test light hooked to ground- I usually use a test light for heavy load testing like a water pump- some times a meter will not put a heavy enough load on the circuit to give a good reading).

The pump was hooked up using an Intellitec water pump controller- a pretty slick little device that allows the coach manufacturer to use multiple switches easily- each switch is a simple momentary switch which is hooked to ground, and all of the switches can be hooked to a single line… less wiring, easy expansion, all in all a pretty nice system.

The “gotcha” that caught me was something that I should have known better (I’ve worked on these before), but….

What got me was that the Intellitec Pump controller switches the ground of the pump, and not the hot lead. Because I had my test light hooked to a good ground, of course the hot lead would be good, but then so was the pump.

This drives home the point- never assume anything, and always understand how the system works while troubleshooting- something I have taught for years, but something that when I am rushed, can still rise up to bite me!

This also brings up the benefit of bench testing- many times there is an external problem in the coach which causes an appliance or item to malfunction. When I bench tested the pump I had removed, it worked fine.

The other point is what I have said before- the Internet is your friend- I’ve used the service manuals from http://intellitec.com/ many times in the past, I knew they were there, and a minute of finding and reading the service manual confirmed my suspicion.

I’ll throw in a plug for Intellitec here- they make a wide variety of RV related electronic items, and many of them are made in the town I live in. The items are generally very high quality, as the assembly lines were also used to make “mil-spec” equipment (though the vehicle products line was spun off from the military products line a while ago). A lot of their items are handy, fairly inexpensive problem solvers, things like slide room controllers, multiplex power controllers, climate controls, etc.