J608

[Stubbie]

HELP from the forums experts required .. no guessing please -
Has anyone on here had to replace the J608 module ?
Whilst driving home last weekend my leisure battery boost switch illuminated along with the side step switch. I pulled over and could hear the water pump running and relays within the utility cupboard chattering or buzzing (part energised) I switched the red isolator off but this did nothing the water pump still ran and relays number 3 and 4 continued to buzz loudly .. I pulled both relays out and then unplugged the water pump .. and continued home .. once at home i found the exterior light was on. I pulled the j608 blue plug, waited 10 mins and then plugged it back in followed by the red switch ..the relays still buzzed when plugged in along with the water pump constantly running . Oh and the interior lights also came on. Basically nothing on the van would work as it should. 2w’s prior to the J608 meltdown my usb and gas burner igniter fuse blew .. this is the second time this has happened, in each instance the fault was traced to the over head cab (top passenger side) usb port (I struggle with the idea that two very expensive Porsche part number USB ports could both be faulty) .. For info, my van is equipped with the standard RV solution li-ion twin battery system .. I have isolated this prior to taking the van to my local dealer and I do not suspect this to be related to the faults I’m seeing.. at the moment that is.. .. I have now lost a huge amount of confidence in my year 2023 GC600 .. I can’t even work out how the J608 is fed, clearly it’s from the under bonnet leisure battery, is this direct from the terminal by a fuse or via a second fuse rail to provide discrimination ? Where are the water pump and exterior lights fused ? I always assumed it was from the utility cupboard .. clearly this is not the case ..
by the way my leisure battery and Li-ion batteries were showing a healthy voltage and charge .. this is not a battery problem ..
my big worry is that an intermittent short circuit on the usb circuit is resulting in a voltage spike that’s damaging the control module .. my local dealer seems reluctant to pursue this avenue ..

 

[sidepod]

Always the first question, plug in the diagnostic and check for codes?

 

[Roger Boeken]

HELP from the forums experts required .. no guessing please -
Has anyone on here had to replace the J608 module ?
Whilst driving home last weekend my leisure battery boost switch illuminated along with the side step switch. I pulled over and could hear the water pump running and relays within the utility cupboard chattering or buzzing (part energised) I switched the red isolator off but this did nothing the water pump still ran and relays number 3 and 4 continued to buzz loudly .. I pulled both relays out and then unplugged the water pump .. and continued home .. once at home i found the exterior light was on. I pulled the j608 blue plug, waited 10 mins and then plugged it back in followed by the red switch ..the relays still buzzed when plugged in along with the water pump constantly running . Oh and the interior lights also came on. Basically nothing on the van would work as it should. 2w’s prior to the J608 meltdown my usb and gas burner igniter fuse blew .. this is the second time this has happened, in each instance the fault was traced to the over head cab (top passenger side) usb port (I struggle with the idea that two very expensive Porsche part number USB ports could both be faulty) .. For info, my van is equipped with the standard RV solution li-ion twin battery system .. I have isolated this prior to taking the van to my local dealer and I do not suspect this to be related to the faults I’m seeing.. at the moment that is.. .. I have now lost a huge amount of confidence in my year 2023 GC600 .. I can’t even work out how the J608 is fed, clearly it’s from the under bonnet leisure battery, is this direct from the terminal by a fuse or via a second fuse rail to provide discrimination ? Where are the water pump and exterior lights fused ? I always assumed it was from the utility cupboard .. clearly this is not the case ..
by the way my leisure battery and Li-ion batteries were showing a healthy voltage and charge .. this is not a battery problem ..
my big worry is that an intermittent short circuit on the usb circuit is resulting in a voltage spike that’s damaging the control module .. my local dealer seems reluctant to pursue this avenue ..

please change your profile : it says T5 Se , I had to read 2/3 of the thread before I knew you're talking about a GC600

 

[Stubbie]

please change your profile : it says T5 Se , I had to read 2/3 of the thread before I knew you're talking about a GC600

Ah sorry I’m on my 5th California now and my t5 remains the best one to date .. don’t ever buy a GC is my honest recommendation .. nothing comes close to the misery that one of these will do to your life .. no wonder prices are low

 

[GordonH]

The J608 KFG is associated with BOTH batteries as it is the interface between the main vehicle CANbus and the leisure SSM CANBus. It does all the power switching logic (the E153 control panel on the wet room wall is just a display and touchscreen). I haven't checked with my GC but from the VW wiring schematics the associated fuse holders are B and D under the passenger seat (UK). B Is starter, D is leisure. There appear to be 4 starter battery connected power pins on the J608 - SB8, SB42, SB43 & SB49, they may not all be populated on a GC. Fuse holder D, the leisure battery side, shows as fuses SD1 & SD3. I haven't heard of any failures of the J608 so it's not a common issue. As you have an RV Solutions lithium conversion it is certainly worth a call to them first to get them to check things are working as expected with their system - two USB power supplies and the gas ignition going faulty point at something wrong with the leisure side of the system. It's not a VW supplied or supported system and the VW dealer is unlikely to be able to diagnose any issues with it.

 

[Stubbie]

Group 1 VW van center Norwich have been beyond excellent .. everthing was undertaken FoC under a factory goodwill gesture, the tech spent several days investigating and replaced the J608 as this had failed, I was unable to speak with their master technician but he is going to call me, so I can ask the questions that will alleviate my fears, confidence in the van is far from high .. I’m not going to reconnect the RV Li-ion system until I have spoken to the master tech and then Tom at RV. Regarding the USB port failure they have a new one on order and have checked all the wiring where they can gain access. Whilst they didn’t say so, I can see an area of concern that had regarding the use routing and the over head cab bed support has been rerouted and the wiring is no longer passing over a sharp edge. A concern I do have is that the ECU failed in an unsafe manner .. i.e circuits directly powered via the ECU were powered / part powered, when I read through the Self Learning module it said if the vehicle was in motion .. the water pump is stopped and the exterior side door light .. etc ..switched off .. this was very much not the case…
Thanks for the info supplied