I'll talk to my friend tomorrow and suggest taking a look onto the leak on jacks before attempting any repair, since I haven't seen the car nor was I present when the mechanic explained the problem with the rack. I'll keep you updated and will post some pictures if possible. Thank you all for the he...

Thanks Neil! I was researching a bit today on the internet and I think I found a couple of intermediate solutions to test the system: 1) Get a DIN-to-RCA adapter to test the amplifier. This way I can feed the amp with any external source like a mobile phone connected through the RCA. I might even be...

Small update: the DIN-jack adapter I bought sadly does not fit the DIN connector at the amplifier, so could not test it that way. But I did check the following: At the amplifier end of the DIN cable I could only measure voltage at the central pin, which according to the image I included in my initia...

Last update: after trying with up to 3 different relays, I read online about another common problem of these old Volvos that leads to a similar problem than mine: a defective antenna ring. I installed a new one 5 days ago and so far I haven't experienced the no-start problem again (knock on wood). S...