VW Crafter EV Alarm Failure: Siren Communication Issue

As someone with moderate experience in EV repairs, I dealt with a similar alarm system fault on my 2018 VW e-Golf. The symptoms were identical, complete alarm failure and a siren communication error in the fault detection system. After some troubleshooting, the workshop discovered the issue was related to corroded wiring connections at the alarm controller unit. The signal problem was caused by moisture getting into one of the main connector plugs. The repair involved cleaning the connections, replacing damaged wiring, and applying protective coating to prevent future corrosion. The fix cost 95€ and solved the issue completely. No problems since then with the alarm disarm function or any other alarm-related features. To better assist with your specific case, could you share: Have you noticed any water damage or exposure in the vehicle? Does the alarm make any sounds at all when trying to arm/disarm? Are there any other electrical issues present? Has the vehicle been in any accidents or had body work done? This information would help determine if your Crafter is experiencing the same connection issue as my e-Golf did.

Last serviced 2 months ago at 115396KM. From my experience, it seems like the same vehicle security issue you described. I checked for water damage near the alarm module but found nothing obvious. The alarm is completely silent, no chirp when arming/disarming and no response to forced entry tests. No accidents or bodywork, and all other electrical systems work perfectly. I did notice the alarm LED on the dash stopped blinking entirely after the security breach occurred. Given the similar fault detection codes, I will have the wiring connections checked. The only difference I notice is that my siren seems to have no power at all, while yours apparently had intermittent function. Would you know if checking the fuse box is worth trying before taking it to a workshop? Want to rule out simple fixes first.

Based on your situation, definitely check the fuse box first. In my case with the e-Golf, I initially checked the fuses as well, but they were all intact. However, its still a good starting point since its an easy fix if thats the cause. The complete silence of your alarm system and the non-blinking LED actually points more toward a power supply issue than the wiring corrosion I experienced. My alarm LED would still blink occasionally before failing completely. The signal problem in your case seems more severe. When my alarm controller was examined, the workshop found that even with corroded connections, some power was still getting through intermittently. Your symptoms suggest a complete break in the circuit somewhere. A quick tip before heading to the workshop: check the voltage at the alarm module connections if you have a multimeter. In my repair experience, this helped identify whether power was reaching the unit at all. Just remember that vehicle security systems can be complex, so if the fuses check out and you cant spot any obvious wiring issues, professional diagnosis might be necessary. The repair costs should be similar to what I paid if its just a wiring issue, likely around 100€ for parts and labor.

Thanks for sharing those troubleshooting details. After checking the fuse box, I found all alarm-related fuses are intact, so thats not the simple fix I was hoping for. Based on your experience and my symptoms, especially the complete power loss to the siren and LED, I think you might be right about it being a circuit issue rather than corrosion. I followed your advice and used a multimeter to test the alarm controller connections. Getting zero voltage readings, which confirms the complete power loss to the alarm system components. This is different from your intermittent signal problem, suggesting I might be dealing with a more severe wiring break. Going to book it into the workshop next week. The fault detection system is still showing the same siren communication error, so at least I can give them a clear starting point. Hopefully the repair costs stay around 100€ like in your case. Will post an update once I know what the actual issue turns out to be, as it might help others with similar automotive alarm failures.