I'm now beggining to understand why this section of the forum is so rich. I've never had to spend so much time with a voltmeter and under the dashboard with my Volvo... 
It's a 1984 2.0 Euro Spider Veloce (Electronic ignition, carbs)
The problem started by me noticing I had about 6.4v at the coil when it should have been 12v. Disconnecting the radio seemed to solve the problem (for a few turns of the key), but it clearly came back...
Now I recon I have an intermittent problem -
Voltage at fuses all read 12.5 - 11.3v except fuses 6,7,8 that read anything between 7.2 - 4.5v.
I spent the evening with electrical cleaner going over all the connectors I could find, as well as pouring over the wiring diagram. Things did seem to improve (hit rate getting 12v when turning the ignition key increases)
One connector looked suspicious (the one the PO wired in the radio).
Any ideas what this problem is consistent with (ex: a faulty relay, a fried wire...) ?
The car does not have electric windows or airconditionning. I can take photos tonight if that can help diagnostics. Thanks to any kind soul that can help.
It's a 1984 2.0 Euro Spider Veloce (Electronic ignition, carbs)
The problem started by me noticing I had about 6.4v at the coil when it should have been 12v. Disconnecting the radio seemed to solve the problem (for a few turns of the key), but it clearly came back...
Now I recon I have an intermittent problem -
Voltage at fuses all read 12.5 - 11.3v except fuses 6,7,8 that read anything between 7.2 - 4.5v.
I spent the evening with electrical cleaner going over all the connectors I could find, as well as pouring over the wiring diagram. Things did seem to improve (hit rate getting 12v when turning the ignition key increases)
One connector looked suspicious (the one the PO wired in the radio).
Any ideas what this problem is consistent with (ex: a faulty relay, a fried wire...) ?
The car does not have electric windows or airconditionning. I can take photos tonight if that can help diagnostics. Thanks to any kind soul that can help.