A quick check found that fuse #7 had blown. The next fuse blew as soon as it made contact.
I got my voltmeter out, and measured the resistance from the fuse block terminal to ground--0 ohms. I pulled the radio out and disconnected it; still 0 ohms. Then I disconnected the amp; still 0 ohms.
I searched the database at this point. There are a couple of reports of the radio fuse blowing with the radio & amp unplugged, but no solutions posted.
So I went and dug up a schematic. It's a 1996 service manual that I downloaded some time ago. The relevant pages are attached below.
Next I disconnected the C/CR connector behind the radio; still 0 ohms. Then unplugged connector 24/13A from under the dashboard. Now I'm getting somewhere--the short from the fuse box terminal to ground disappears and becomes an open circuit. Measuring from the unplugged connector pin #1 to ground is 0 ohms.
So the short circuit is in the cable harness, on one of the two black and red wires connecting 23/13A pin #1 and C/CR pins #4 and #12. The schematic indicates that there's nothing else connected to these wires between the two connectors.
Today I took the dashboard cover off hoping to take a look at the cable routing and maybe find some damaged or melted insulation, but couldn't see anything wrong. I wiggled the cable harness in various places to see if I could make the come and go but nothing happened.
I need to drive the car this week so I put everything back together with the radio disconnected.
So, my questions to the group:
- Have anybody else seen this? It's been reported a few times on this board. Is there a common cause/solution?
- Does anybody have any tips or suggestions on how to find a short in a wiring harness? Does anybody know exactly where these wires run?
- Does this schematic look correct? Could there be another device attached to the black and red wires on that harness that's shorting them out?
- Anybody see any mistakes or flaws in my reasoning?
I'd love to hear peoples thoughts---what do I do next?