Birdman Fusebox #2 keeps popping

Add'l photo + wire color description helps a ton.

I suspect the problem is downstream. While your wiring seems to have been re-crimped into diff't connectors, it still kinda looks to be the right loads. Here's what I think you have:
L1
- Front Conn: Blue/black = windscreen wipers + Red = brake light
- Rear Conn: Yellow/black = turn indicators (you were right...I read the schematic wrong, hazard light supply comes from L6)

L2
- Front Conn: 2xRed wires = electrovalve or seatbelt relay or reverse light + Red/black = reverse light OR electrovalve supply
- Rear Conn: 2 x Green wires = instrument gauges supply + slowdown indicators

You've already confirmed that disconnecting L2 (rear) kills the gauges. If you disconnect L2 (front) does it kill the reverse light and the little seat belt indicator in the middle of the dash when you switch the car on? If so, then you've confirmed that all of the correct loads are on L2. In that case the problem is most likely to be downstream (gauges, reverse light, seatbelt relay, electrovalve relay or the electrovalves themselves).

And you are correct about the 16A vs 8A fuse. It should be an 8A fuse. It's low likelihood you're running a fire hazard (factory usually sizes the wires to handle 3-4x the rated fuse current), but it certainly would be masking a problem if you don't run the rated fuses.

You've said that L2 fuse blows after running for a "while". Assuming that your seatbelt relay isn't going on/off all the time and that it hasn't been blowing as soon as you put it into reverse, then the most likely candidate is either the instrument gauges OR the electrovalves. Because it seems to blow when the engine starts to warm up, I put money on the electrovalves.

How comfortable do you feel with an ammeter? *WITH THE CAR OFF*, I would disconnect the instrument gauge connector (L2 - rear conn) and reconnect it thru the ammeter (hopefully you have an ammeter that can handle 10A). Then turn the car on. It should be less than 3-4A. Assuming it's fairly low, then your problem is in the electrovalves (either the relay or the valves themselves).

If you're not comfortable with an ammeter, then have your shop guy do it. Ammeters are no joke--hooking them up wrong is not fun. Alternatively, if you have a set of glass fuses you're willing to blow, put the correct 8A into the socket and disconnect your gauges (L2 - rear conn). Then go for a drive (the gauges don't need to work in order to drive the car). If the fuse blows again--guess what? The problem is in your electrovalves. If it doesn't blow, then try it the other way around (connect the gauges and disconnect the electrovalve (L2 - front conn)). Go for a drive. See if it blows (your car may not drive very well w/o the electrovalves, btw).


Also, one last thing to point out in your fuse layout that I didn't see before. It would appear that the supply side (top of the fuse block) for L3 is jumpered to L1 & L2 (you can see a little copper bar behind the spade connectors. That is definitely weird. All of the carb'd 308s & GT4s had L1/L2/L3 shorted supply side of the fuses and they came from ignition switched power. However, *all* of the fuel injected 308s separated out L3 supply from L1 & L2 -- and was supplied with non-switched power (direct from the battery). So it would appear that your Birdman left side fuse block is for a carb'd 308 (he sells a version for an injected 308 that separates out that supply for L3). This is the only difference btw the two versions and I don't think it's the source of your trouble, as you symptoms would be very very different. However, back when this was originally installed, it caused someone a lot of headache -- effectively if you'd connected the stock wiring you would have shorted out live battery and ignition switched power. In other words, the car would have always been on (not running, just on) even when you turned the key off. I'm guessing that un-insulated (bad!) connector going to L3 is a radio or alarm load and no longer a supply line. Your fuel pump circuit basically gets it's power from ignnitition switched power now. Again, this isn't the source of your trouble and is probably just fine. But you should realize that your wiring is definitely different from the way it left the factory...but I suppose you already realize that

Sorry and hope some of this is helpful and not too much of a wild goose chase. And also sorry for the very long, verbose response. My wife complains to me all the time about my verbosity.

 

The "electrovalves" are just electronic valves in Italian-speak. They are part of the emissions control system, controlling both the EGR (exhaust gas recirculation...or "ricirculation" if you're the guy in Italy tasked with translating the manual into English) and the air diverter which controls air to the catalytic converter. Both of these definitely actuate only when the temp rises above a certain point. There is also an electrovalve for the fast idle (this one I don't understand the function all that well).

When the manual states that circuit controls the "engine high temperature control system", it's actually talking about the same electrovalves. One of the benefits of the air diverter is that it prevents the build up of high back pressure in the exhaust system...effectively helping to prevent high temperatures in the exhaust.

 

That's weird. Your oil pressure warning light and cold engine light should *both* be powered by the same supply as the rest of the gauges. Did all of the gauge indications die when you pulled that front connector (e.g. water temp, oil pressure, handbrake warning light, etc)?

You'd said that the rear connector (w/the green wires) killed the gauges...so maybe they re-wired to put some of the gauges on the other connector? That just doesn't make a ton of sense--that harness is pretty buried behind the dash and you'd have to be pretty intentional to pull the oil pressure + cold engine warning lights onto a separate wire.

Well, I'd still recommend getting 3-4 glass fuses (8A) and try running the car with only one of those connectors connected. Find the one that actually blows the fuse. And then start tracing.

 

"Ammeters are no joke--hooking them up wrong is not fun."

Absolutely correct! Checking for 12 VDC when you have not noticed that from the last time you used the multimeter, the probes are plugged into the 10 A position is VERY exciting!

I do NOT recommend it.

 

Depends on the multimeter. On my Fluke multimeter nothing happens. Except, that a big $20.00 fuse, which is easy to replace, blows.

Best from Germany
Martin

 

Yep, Flukes are great but I suspect that a lot of folks use multimeters that cost not much more than that Fluke fuse!

Incidentally, though you wont damage the meter, the tips of the fluke probes will disintegrate in a literal "flash" before that fuse will blow. I have the T-shirt for that as well.

 

Yeah...the Flukes are so nice. I have a number of multimeters at home, but my go-to is still a Fluke 77 that my boss gave to me as a college graduation present back in 1990 (still lists among one of my top presents of all time). If you do a lot of electrical work, pick up a used one off of EBay -- get an 87 tho as the 77's are very very long in the tooth.

Fluke is also a great company. A few years ago, we picked up a used one at the shop at work, found that it wasn't reading well on the DC mV settings -- Fluke had us send it in and they repaired and recalibrated it for free. Not sure they'll always do that, but it definitely converted our shop to lifelong Fluke fans.

But, of course, the $30 meters work fine if you're just testing to see if your battery got voltage or tracing out continuity on a wire harness.

 

When the electrovalves were removed what happened to the wiring? Abandoned in place, or removed back to some disconnection point? If they are just hanging out someplace perhaps the connector is touching ground and when it gets energized by the thermoswitch it pops the fuse?

 

Holy cow! Is that the same engine bay? So shiny!

I was gonna ask the same as Mr. Harper...did the electrovalves (or the fast idle) just get tucked away somewhere?

 

Prashant,
Did you finally get this resolved? Was it the remnants of the electrovalve wiring shorting out that caused the fuse to blow?