Today, using a page from the Webasto Thermo top C E & Z Installation Manual I set about testing the Combustion Air Fan and the Circulation Pump to check their operation.
Why, because my FBH is not operating as it should. When pin 3 is earthed the Water pump runs for 124 seconds then stops, no other activity happens.
The PCB has been repaired by FrenchMike, a new Dossing pump has been fitted and primed, and a new Landrover Temp Sensor has been fitted inside the front bumper.
In the diagram above, X5 is the Circulation pump power feed and X4 is the Air fan feed.
These are the same as the labeled picture below (thanks to FrenchMike)
Both the Air fan and Circulation pump powered up when given a 12v feed.
Why then won't the FBH fire up and run normally when powered up?
All posts I can find on the forum say that when powered up the Air circulation fan kicks 1st, not so in my case.
Other than taking the PCB out and returning to FrenchMike to be checked again I'm at a loss.
Has anyone any thoughts on this please?
Charles