Hi all, it's been a while since my last post on this subject but I have a new update after some trouble shooting over the weekend. I did some research on this forum, but also some other car forums with specificly searching on the subject 'overheated coil'. Based on that, and together with the Blue Books I started checking the altenator and regulator today. I think a lot of things can be explained after what I have found.
Some additional background info:
I have been driving a couple of times last summer, but always quit close to home with a fully loaded battery (still afraid that the car would let me down..). When the car is not being used I always attach it to a CTEK battery loader. When starting the car the warning bulb of the battery capacity/voltage on the instrument cluster was always lighting up, since I think 1.5/2 years but I can't remember exactly anymore. But after driving for some time it slowly got weaker and weaker and almost went out when being back home. I always thought that it was related to the fact that I drive the car maybe 5/10 times a year during the spring/summer period. With only having the battery loader I assumed that it was a little bit lower on voltage then when you really drive the car with the altenator loading the battery.
Yesterday I checked the voltage as described in the blue book over B+ and D-. While it is a bit difficult attaching the measuring pin of the voltage meter to B+ because of the little amount of space it only gave 0.24V. To be honest I couldn't believe that, I also did a test with a bulb tester but that also didn't glow. For me that was the sign to take out the alternator and the regulator, but with disassembly of the regulator I noticed that the D- plug was burned away and even the cable was burned through. I never noticed because it was still in the plug looking as being normal.
Whit this knowledge I think I can now explain on high level why the car is showing issues, but I do not fully understand it. Is it correct that if you cut your D- between the alternator and regulator that the battery isn't being loaded anymore? And the question is how this could happen, I think the regulator is broken and that caused high voltage peaks into the wiring harness with finally the D- plug being burned down and even a burned through wire. I also had a small melted headlight plug last year, an indicator instrument light that only worked for one time on the instrument cluster after you turn on your indicator but the indicators on the car still continuing blinking. This might be related to this also, but I think the relais is the issue which is also showing issues since 1.5/2 years.
Finally this should then lead to a heated coil? Is that possible? I need to do some analysis myself based on the findings, but any comments from your side would be appriciated.
I have decided to order a new voltage regulator and let my alternator check by a professional (while I'm not sure if the alternator is an issue anymore).