#&%/^@$ Webasto

[truk4u]

John,

My book shows a pre-heater button, but no joy in mine. Must be they did away with this around my build time.

[MangoMike]

Doesn't look like I have a preheat on either the Liberty or the Marathon.

Plus...
I'm still trying to fiqure out this model Number - #&%/^@$

[gmcbuffalo]

Are we sure the Pre Heat button is not a switch to turn on the Webasto to pre heat the engine, like a electrical pre heat?

The test only applies 12 or 24 volts to individual functions of the Webasto, so look at the functions of each pins on the brain connectors and apply the correct voltage and see if all systems work.

Did you test the spark and listen for the clicking sounds of spark arcing?

GregM

[flyu2there]

Guys,

Both of the manuals that I have, one from Mango and the one I ordered from Fort Lupton some time ago (How to install a Webasto in your Peterbilt), indicate that these units have Pre-Heaters that heat the fuel prior to it being sprayed out thru the nozzle. My CC has an annunciator panel on the overhead with or about 20 lights. Several of the lights are also switches however the Webasto Pre Heat it is merely an indicator light. Looking forward, at the 10 o'clock position on the Webasto unit itself, you will find the handy dandy feeler gauge for adjusting the ignitors, AND at the 2 o'clock position, also mounted on the case I find a relay......looks very much like a turn signal relay. This relay draws power from the A block on the brain (power in, small one)...........................

Here is the two fold question. Does everybody see this relay on their Webasto???? Wonder what the control is for this relay and if its failure might prevent the Webasto from runnning..........these schematics are tuff to read. I am trying to trace thru them....lets see, shown in the relaxed and open position....

Naw, couldn't be that this coach was originally going to ship to Edmonton....CC isn't that bright....


John

[dreamchasers]

John,

The schematic that I have shows the relay to be in the pre-heat circuit. Check out the schematic pages, page 9. Mine is a model 2010.

http://www.suremarine.com/manuals/we...300-repair.pdf

I normally look at a schematic as being in the 'de energized' state, unless otherwise noted. So the relay would be normally open, de energized. The S2 switch in the relay circuit would be at normal temperature 70 degrees (NC).

Hope this helps.

Hector

[flyu2there]

O.K....talked to Webasto pretty much came down to the brain. Mango sent one out and I hooked it up...NO HELP.

The pre heat thermostat only operates if the ambient temp is blo 32f....so that's outta the equation.

Back to the ohm meter to look at continuity...then another call to Webasto Tech Support.....

Running out of Airspeed, Altitude and Ideas.............


John

[Jon Wehrenberg]

John, I am late to this party but step one should be to keep the wings level...

I guess if it is not firing the first question has to be if it is getting power. I cannot translate my Webasto operation to Mike's because my coach is a 24V model that uses PLCs to convert the pushing of a switch to the closing of a power circuit. As long as mine works I don't work my way backwards to try to figure out why it works.

Mike's, like yours may have a less complex circuit, and the pushing or flipping of a switch is likely to close a circuit and send power to the Webasto control. Once it is affirmed you are getting power to the unit then the trouble shooting should follow the Webasto diagnostic recommendations.

We have learned the Webasto is voltage sensitive with low voltage creating funky types of malfunctions. I have a spare 24V Webasto control but unless you have a 24V control it will not help. If you do I can send it to you or we can hook up at one of the rallies, TN or NV.

[flyu2there]

Jon,

Thanks for the input. The Webasto and I will show up in Nevada, too late for TN as business got in the way.

I am thinking a faulty ground here somewhere because I have followed the checklist to the letter, at least twice! Both brains...same thing. The pumps run (although they get their signal from the CC Motherboard), the fan DOES NOT START, seconds later the ignition fires. It tries for about 30 seconds and then throws in the towel....I have power where I am supposed to have power (I ground to the chassis) it is just that neither brain will power the fan and fuel pump and gawd knows what else. The photocell checked out ok, all that other stuff is as it is supposed to be and I can jump the brain and everything works, including the fan. I have talked to three different Webasto Tech's and have Three different answers.........I think there must be multiple grounds on the brain. The absolute only other possibility has to do with the motherboard....gawd I hope it's not there.

I now have about 24 hours of apprentice Webasto Training, sitting on my proverbial arse in the gravel, outside. My disassmbly time is noteworthy...I can split the case, pull the coil, pull the fuel lines, inspect, re align the ignitors, ohm and re assemble in about 10 minutes. The only thing that is showing signs of wear, aside from my bottom, is the super cotter pin....it, like me, has about two more times before we both give up and order a new Webasto!!

John

[Jon Wehrenberg]

John,

Verifying the presence of power will go beyond seeing a specific voltage on the multitester.

You may be right on the money with respect to bad ground or it may be on the power side of the wiring.

I had a device in my current coach that would not work. I started testing for power and it read on the high side on my meter. Yet when I turned on the device it would not function. As it turned out there was corrosion at one of two fuses in the circuit and while the circuit would carry current, there was enough corrosion to limit the amount of current it would carry effectively giving me the false impression the device was getting power, when it was actually suffering from low voltage due to the resistance caused by corrosion. As soon as any load was applied the voltage dropped significantly.

From your description of the cycle can you measure the voltage at the device through the various phases of the cycle that you see? It seems that some portions of the operating cycle less affected by low voltage such as a fan motor are working, but when the real load kicks in, that being the fuel pump which I think pulls some amps the cycle seems to come apart.

I cannot address the CC interface because in our installation a command to start the Webasto closes a relay supplying power and from that point on only the Webasto brain handles the various functions and phases. I think our circulating pump is exclusive of the actual Webasto brain and other functions.

[MangoMike]

I would think that the coil, which is firing, would draw as many amps as the fuel pump.

The brain is getting power and then starting it's cycle as shown by the coil firing. And we know the brain is good. And we know that power directly to the motor starts the motor. So is it a wiring issue from the brain to the motor? I would double check all those connections again on the A connector.

I'm really stumped on this one and it seems like FlyInTheWeb has tried just about everything.

Mike