I have a P1632 DTC: "ECM (PCM) judges battery voltage below 8 volts" and one of the listed causes is a damaged ROOM fuse.
So, what is the room fuse, where is it, and how can a fuse be damaged without being blown?
I thought fuses either have continuity and work, or they're burned and don't?
I looked in the fuse box under the hood, and didn't find it there, and the fuse panel under the dash doesn't have any labels, so I don't know which fuse is which.
I have a US Haynes manual and the wiring diagram shows it in the "joint box" together with the engine fuse, but I don't know where the "joint box" is and if it's the same on European GF models ( mine is a 98 2L GF ATX ).
I also have a scan of the 97 EU WSM, but other than the DTC description I couldn't find any reference to it's location.
EDIT Aug. 8th 2017
OK, so I've made some progress. I found two fuse under the dash that are hot ( B+ ) with the key off, a 10 amp and a 30 amp. Both fuses visually looked just fine. I then disconnected the ECU / PCM harness and started checking the voltage on all the pins ( hooked to the negative battery post ). I found multiple grounds which were all about 0.01V, although a few started at 0.1V and dropped to 0.01 after a second or two.
I also found three pins on the ECU harness which where hot, 1. with B+ ( 12.66V ), 2. 3.55V and a 3. with 3.13V. ( just labeling them for reference )
When I pulled the 30 amp fuse it didn't do anything, when I pulled the 10 amp fuse, 1. went down to 1V and 3. went down to 0.04V, and they both dropped steadily over about five minutes, with 1. down to 0.29V and 3. down to 0.01V.
The way they slowly dropped like that makes me think there is a capacitor in the path somewhere.
Neither fuse affected pin "2", which always stayed at about 3.55V.
Under p1632 in the 97 EU wsm it says pin 55 should show 10.5V and if it's not then to check the wiring harness between the battery positive terminal and the PCM for a short to ground.
According to what I could discern in the WSM, I should have VPWR B+ on two pins and then the aforementioned 10.5V backup power on one other pin.
I guess the question is what do I do now? I have no wiring diagrams and don't know which pin is which. I'm not even sure if that 10 amp fuse is in fact the ROOM fuse.
I'm wondering if maybe I'd just be better off taking this to a Mazda shop that will ( I assume ) have wiring diagrams and know exactly where to look to track this down...