VW Caddy Won't Start: Terminal 15 Power Supply Issue

Having dealt with a similar issue on a VW Golf 2008 gasoline model, I understand your frustration with starting problems. As someone with moderate experience in car electronics, I found that voltage drop issues can be tricky to diagnose without proper testing equipment. My car displayed multiple error codes and had an intermittent starting problem. After checking the obvious points like the fuse box and battery connections, my mechanic discovered a damaged wire connection in the main wiring harness near the steering column. The power supply to various control units was affected due to a loose terminal connection that had developed corrosion. The repair involved cleaning the connection points and replacing a section of the wiring harness. Total cost was 95€ including diagnostic time. Car has been starting perfectly since then. To better assist with your specific case, could you provide: Complete error codes from the scan, Whether the problem occurred suddenly or gradually, If you notice any other electrical issues when using the key, Whether the battery has been tested recently This information would help determine if your issue matches what I experienced or points to a different cause.

After visiting my mechanic with this starting issue, we found the relay switch for terminal 15 was faulty. A voltage drop test confirmed power wasn't reaching the ignition circuit properly. The starter solenoid was receiving inconsistent voltage, explaining why the car won't start despite having good battery readings. Last service completed at 65872km showed all other systems working normally. Once we replaced the defective relay and cleaned the connecting terminals, the starting problem was resolved. The repair took about 2 hours, costing 180€ including parts and labor. Still monitoring to ensure no underlying wiring harness issues develop, but so far the fix seems complete. If anyone needs the specific part number for the relay, let me know.

Thanks for sharing your repair experience. The faulty relay switch causing voltage drop matches exactly what happened with my VW Golf too. After replacing my damaged wiring harness, I also had the ignition switch and related relays inspected since they can deteriorate over time. Good call on having your mechanic do a voltage drop test, it's crucial for diagnosing these terminal 15 issues properly. When the starter solenoid gets inconsistent power, it often triggers multiple error codes that can be misleading. My advice would be to keep monitoring the circuit breaker and fuse box connections around that area. In my case, the initial relay failure was actually caused by slight corrosion that had spread from nearby connections. A quick cleaning with electrical contact spray every few services can prevent these issues from recurring. The 180€ repair cost seems reasonable considering the diagnostic work needed to pinpoint relay switch problems. This is definitely a more cost-effective fix than replacing the entire ignition system, which some shops might suggest.

The relay switch replacement resolved my starting issues completely. After driving for another 2000km, I can confirm the power supply to terminal 15 is working perfectly. The voltage drop test results have remained stable, and the ignition switch engages smoothly every time. For reference, my total repair included: Faulty relay replacement, Battery terminal cleaning, Wiring harness inspection, Complete system diagnostic scan The 180€ investment was worth it considering the alternative of being stranded with a non-starting vehicle. The mechanic mentioned these relay failures are somewhat common on this model year, often caused by normal wear on the electrical contacts. I recommend anyone with similar starting problems specifically request a voltage drop test at terminal 15 before replacing more expensive components. The error codes alone can be misleading without proper circuit testing.