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WEBASTO Coach Wiring

Yahoo Message Number: 109331
Two schematics came in the Big CC Notebook ( Dated: 4-16-96 & 6-21-95) for Hydronic Heat System. Neither is accurate for CC's connection to the Webasto unit in my coach. HELP I need to know where wire #42 16g ORN goes after it departs the Webasto bay. It conects to the Preheat Relay and then goes into a big wire bundle. Both diagrams show it going to the Webasto Preheat Thermostat. The only Preheat Thermostat I find on Webasto drawings is located INSIDE the unit.

Wire #42 appears to be a switchable ground and is needed to activate Relay H in the Electrical Bay. Relay H sends 12v to activate both circulation pumps. NOTE: Webasto Control Unit Plug "A" does NOT feed to #H9 nor #H34. Those wires feed off a connection from the Preheat Relay.

I've used a temporary jumper wire to activate Relay H and both pumps operate allowing the Webasto to function without any problems.

Anyone have an accurate schematic or personal knowledge of where that elusive #42 ends up?

Digger Graves
99 Magna #5723
08 Yellow Jeep

Re: WEBASTO Coach Wiring

Reply #1
Yahoo Message Number: 109341
Hey Digger

I believe my year 2000 Magna 36 has the same wiring diagram that you have and I don't have a Webasto "˜pre-heat' switch that I know of. I figured that the preheat circuit was built in and the wiring Harness was "˜generic' and doesn't use all the wires.
My Webasto works well and you didn't say, but I gather you are having problems. Mine wasn't working well when I first got the coach but after exercising all the blade connectors things started to work. I found the Webasto very difficult to trouble shoot, and even harder to find someone available to do it for me on my schedule. I finally bought a test box, it was easy to use and pointed out my problem. It also has a button to test the pumps through the wires #H9 and #H34.
I don't see where the pre-heat circuit would have anything to do with the pumps. The power for the pumps comes from battery thru wire #420, thru #403, thru relay H (controlled by H34 to the ground H9) and to the pumps, Wire H10. The Webasto plug does not power the pumps.
Good luck, I hope I've helped.
Ed

2000 Magna 36 #5738
Ed Recknagle
2000 Magna 36  #5738

Re: WEBASTO Coach Wiring

Reply #2
Yahoo Message Number: 109355

Ed,

What a surprise to read your response on Christmas Day! Having your own Webasto Test Box has got to be a real sanity saver. Of course, I didn't have permission to "play" with the RV until today. Everything you stated is confirmed. There is a pic of the wiring diagram that came from CC that shows H 42 making connections. Tomorrow, unless we head to VA, I plan to include a schematic of how it is actually wired; to include that Wire H 42 that goes of to ............

Sure appreciate your clear thoughts and rapid reply.

Digger

99 Magna #5723
08 Yellow Jeep

Re: WEBASTO Coach Wiring

Reply #3
Yahoo Message Number: 109369

Ed,

You are probably right about the H 42 being an unused wire. I thought it could be the source for the missing Ground to activate the relay. However, it appears Ground should continue out of the connection to a component inside of the Webasto. In the sketch below, there is GOOD Ground TO the Webasto component (Blue/Green wires) but NOT out. There is NO continuity between the components terminals. Like a burned out light bulb, the circuit is OPEN.

Now I need to know:

(1) What that Webasto internal component is

(2) Should there be continuity between it's terminals.

I've got to get this solved because the HWH leveling system is acting wacky!

Re: WEBASTO Coach Wiring

Reply #4
Yahoo Message Number: 109388

Digger,

First understand that I am not a Webasto expert, everything I think I know is from reading online or playing with my own unit. I cannot answer your questions directly, but maybe this will help.

The "˜Service/Repair manual' for your Webasto is available to download free on line. It has wiring diagrams, trouble shooting tables, plug-in drawings, component ID, etc. Attached is the drawing of the control box plugs from that book. Connector A is for the pump control wires, not pump power. Connector C wires all go to the Webasto, and Connector B wires all go to the Coach. The wire plugged into B1 is the signal from the thermostat. B2 is the ground for the whole thing, all circuits are completed thru it. B4 is constant Power. B5 is not used in my unit. B3 and B6 are for indicator lights by the bed on my coach near as I can tell.
Also attached are Photos of my wiring diagrams, I think they are the same as yours.
Good Luck
Ed

2000 Magna 5738
Ed Recknagle
2000 Magna 36  #5738

Re: WEBASTO Coach Wiring

Reply #5
Yahoo Message Number: 109405

Ed,

Done!

The Webasto is working normal.

You made an excellent explanation of circuitry connections that led to discovery of two wire connectors REVERSED. A Webasto forum at http://forum.rvhydronicheaterrepair.com is an absolute must to keep in your "Webasto tool box." Roger Burke runs the site because he is a Webasto/Aqua-Hot Certified Technician, he can rebuild units, and has parts for sale as well. He identified the component inside the Webasto I needed to know about for continuity. With his information plus your clarification, I discovered that someone had reversed two of the wire terminals (R & H) that snap together! After correct connection, the CC drawing provided is accurate.

I've attached a sketch of my current wiring diagram that shows how the CORRECT wire-end terminals are connected.

Thanks again for all your help.

Happy New Year,
Digger Graves
99 Magna #5723
2008 Yellow Jeep

Re: WEBASTO Coach Wiring

Reply #6
Yahoo Message Number: 109410
Good Job Digger,

I'll have to check out that forum.

Ed
Ed Recknagle
2000 Magna 36  #5738