Testing and Diagnosing the E5. Webasto Thermo Top CZHaving managed to sort out my aux heater, with a lot of help from this forum and elsewhere, i thought of publishing my knowledge, for the benefit of others. Theres still the last mile to go in terms of enabling remote start, but thats relatively straightforward once the heater is working properly Background about the Webasto Thermo Top CZ Webasto Thermo Top C is a common heater widely used in marine applications. CZ is the automotive version of it. CZ has a modified PCB, which enables it to talk the cars language. In the case of the BMW E5. K Bus, which is a part of the E5. BMW and MINI parts and accessories are all we do and weve been doing them since 1974. Best price guaranteed. Free shipping most orders over 99. Read and analyze your cars current ECU data, and update it with an optimized costsaving, performanceboosting map file. You can also repair ECUs with various. Tolle Angebote bei eBay fr damos files. Sicher einkaufen. Bmw X5 E53 Service Manual Download' title='Bmw X5 E53 Service Manual Download' />You will notice that the unit has 2 labels. One is the Webasto original, the other is the BMW label with the BMW part number. BMW never planned our cars to be sold with a parking heater option. US version, not sureback to our cars. Because the car manufactures incl BMW have made changes to the PCB for it to talk the cars native language,  the Webasto company or its dealers who are readily able to help with general thermo top parts are unable to help diagnose or replace the PCBGo to BMW they will not give you a PCB, they will try to replace the whole webasto How does the webasto work The Webasto CZ has 2 methods of starting up. Normal Operation with a k bus commandfew important conditions it checks are    water circuit temperature lt 6. C   outside temperature lt 5 C    customer requests more heat from their heater   Im not sure if it does the usual voltage checks. Telestart with 1. Serial Number Generator Adobe Acrobat Pro 9. V to pin 1. This method is necessary for telestart beause the car could be asleep when telestart is requested meaning k bus is asleep Popular theory is that it ignores the temperature checks, but I have found that when the outside temp is like 1. Low Voltage 9. 8 0. Also note the MINIMUM time for the startupshutdown sequence is around 3 minutes, so it is not recommended to power pin 1 for less than 3min. So make sure you make a solid connection, and latch it for min 3 mins before disconnecting. Edit A Fuel System Complication ive learnt E5. The Webasto fuel supply is on the right hand side fuel pick up, some way up from the bottom of the tankTherefore it is not recommended to run the webasto with the fuel light on. Flame Formation faults. Alternatively if the car is at a steep incline with more than even a quarter of the tank full the webasto could still be starved of fuel Diagnosing the Webasto Thermotop CZ If your webasto is misbehaving the first thing to check is connect the Scanner 1. The Scanner 1. 4. I have forgotten where it logs the error, i think its in the ACHeater section this is easy enough to find. If the scanner reports an error that means the webasto has a problem. To do this, running webasto test software along with the ability to issue k bus commands is key. I took the hard but safe path mainly due to my lack of knowledge at that time, with the benifit of hind sight what id do now is actually service the heater first. I purchased the Reslers USB version, which then works with Webasto Test Software which you can download from here. The test guide can also be downloaded from this site. Reslers device connects to pin 2 on the webasto, which is the k bus on the BMW E5. Thermo Top, as below Again it must be noted that the test document seems to be designed for generic car type webasto thermo top cz although you do specifically select BMW and so on. Most importantly the test harness allows the webasto error log to be cleared. Testing individual components with the Reslers pointed out 2 issues to me 1. Glow Plug test showed the below issue. Fuel test should have produced a certain amount of fuel over a measured period of time, it didnt, it produced much less fuel and then the pump stopped The fuel pump was faulty or the fuel lines were blocked and the glow plug was faulty. PCB was faulty and was reporting these units wrong. At this point initial logic would have got me replacing the fuel pump and the glow plug for starters. I spent a few days trying to figure out where exactly the fuel pump was located, how to replace, etc. Having read a lot of ppls experience I somehow had a hunch about the fault being in the PCB. Eventually i thought I should follow my gut feel and that worked PCB that was faulty. PCB on E5. 3 Webastos is notorious if you read through other posts here. BMW has mucked around with it to be fair not just them i think all car manufacturer do this, to make it talk their native languageI called about 7 Webasto dealers to see if they could supply a PCB. Unfortunately none could as they could only source the standard PCB, not the BMW specific PCB which would talk k bus Around this time, possibly due to the frustration of not being able to source a PCB, curiosity got the better of me, and I dug in deeper, which resulted in doing a good service job on the webasto. Webasto Service BMW never intended the webasto thermotop CZ to be serviced. Having said that, the Webasto is like the boiler in your house. Only worse cos it burns diesel oil which produces a residue unlike much cleaner gas which your boiler in the house burns. Made much worse by us smart as. BMW only intended these units to run a few minutes when the car started up. So heres how to service your webasto, which now I believe is necessary, because I think a blocked burner was the root cause of what caused my failure. NOTES BEFORE YOU REMOVE 1. Remove the webasto from the car, as below A remove. B remove. C ignore this is a connector along with labels ive fixed to wires on pins 1 2 so that i can easily attachdetach the test eqpt without damaging the wires by repetitive connectionsA remove. B remove one can only be removed after lifting the unit so will have to be done lastC remove make sure you have spare fuel line clips in hand, the original i think is a disposable typeD the exhaust just wiggle the unit off once verything else is discon. Remove the plastic covers. A remove the 4 screws some have torx, some have philips and remove the PCB cover. B pry out the connector cover with a screw driver, A main connector, k bus and the works. B main power 1. VC glow plug. D Air fan. E Water pump all the literature talk about the water pump being a part of the webasto, in the E5. F blank not sure what this is. G temperature sensor torx screw remove this to remove the PCB3. Remove the air fan unit. A remove the 4 screws. Pull up the air fan section carefully, the diesel inlet stays put. Remove the burner unit and remove the glow plug. A remove the 4 screws torxB pull up the metal clip slowly, that releases the glow plug. C pull the burner unit up slightly, then pull the glow plug out. Inside the heat exchanger once the burner is removed The burner unit now the part that needs service A this is where the burning happens. Glow plug goes right there as well. Clean with a wire brush sort of thing that can be poked in. Job done now put all the pieces back together in reverse order. What else have i found out by now By testing the glow plug resistance i also knew the glow plug was short circuited it shows 0. But the faulty glow plug couldnt have impacted my fuel test so its still the glow plug plus either the fuel pump or the PCB or both. Android 6. 0 Car Stereo GPS BMW E4. M3 Rover. 75 MG ZT DAB Wi. Fi. Postage to Europe. 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