Hello Tried to get the car out of storage and noticed the alarm fob wasn't doing anything and the alarm LED wasn't blinking. Found a blown anti-theft fuse and replaced it and car started and was fine. A couple days later the same problem and now it blows a new fuse immediately when I plug in a fuse, don't even have to turn the key on. Any suggestions before this thing cost me a arm and leg to tow to the dealer?
Found the problem, the alarm siren underneath the passenger side headlight was causing the short. Just disconnected it and the fuse stop blowing and car starts fine now!
Sounds like your battery is going bad in the siren. Replace it with the Corvette siren to save some $$$.
Does anyone know where the anti-theft fuse is located in a 456M? It's nowhere to be seen on the fusebox board.
I haven't made up a wiring diagram for the 456M alarm system, but I was able to deduce the following from pinout diagrams (regarding Immo ECU power): Live battery power comes from the 60 amp maxi fuse maxifuse in the engine bay near the battery cutoff switch. This fuse powers quite a lot of things, including injector power and automatic gearbox stuff (if applicable). Key power comes directly from the key with no fuses. As the Immo ECU controls the starter relay, I assume you have no cranking?
Well, the ignition key is supplied with battery power from fuse 10 in the box above the main fuse/relay panel. Image Unavailable, Please Login Image Unavailable, Please Login Very little on the car would work with this fuse blown.
The red led next to the switches array is completely dead. All power is there in the car, except for the immobilizer. All other things are working, but I can't start the engine because the immobilizer is dead. I have read all posts about the siren battery, so presume the issue comes from a short in the siren. Ferrarifobs has flashed the ECU and fobs some months ago, so that has been working properly. fuse #10 of the little fusebox is OK. Also the big one next to the cutoff switch is ok
Interesting. Can you disconnect the siren? I can give you some pin numbers for the power pins on the Immo ECU, but I believe the Immo ECU is hard to get to. There may be other power inputs I've overlooked. The diagrams are not easy to follow.
Check fuse 9 also in the little fusebox. It's related to the hazard/turn system, but also feeds power into the Immo ECU (for some unknown reason)
This is a common problem with the 360. The battery in the siren leaks, destroys the pcb board inside, then blows the anti theft fuse. Unplugging the siren and replacing the fuse is always the solution for a completely dead car. I’m sure it’s a fuse and not the immobilizer. Immobilizers never fail unless they go for a swim. Here is the location in a 360. I’ve never been told where this fuse exists in a 456. Image Unavailable, Please Login
There doesn't appear to be a dedicated fuse for that. I just disconnected the siren and fuse #9 is also OK. In fact, all fuses in the little and main fuseboxes are fine.
So probably not a power issue unless fusepower is not getting to the Immo ECU. Did you measure power at the fuseholders? Unfortunately, the next step might include checking power at the Immo. Doesn't that involve some kind of rear seat disassembly to get to the sidewall?
The earlier cars didn't have specific fuses for the Immo system (456, 550, 355). Heck, the 355 doesn't even have a fuse for coilpack power. If there is a short in your coilpack wiring, the ignition lock (or wiring) melts. Seems fuses were a luxury in those days
I could test the immobilizer. Mike could too. I’d be shocked if it were the issue. The only ones I’ve seen fail were both flood cars.
I had a problem on my 550 once and never again. I hate the imo system. I hate sirens everyone ignores. So I have my siren permanently disconnected but the imo system still functions to allow car start or prevent car from starting. Once my car would not start after the FOB unlocked my door and let me in. I kept pressing and still no proper action at the red led. So I keep a new battery in the glove box. I changed the battery and the FOB would still not function the KED but the red light on FOB would work with old battery or new battery. I took the battery back out and pinched the metal FOB contacts in and spun the battery to ensure contact. This still did not work. Then I used the PIN code and car started fine and I drove home. Then I got my other FOB and it worked fine. So of course I take the broken FOB and now it works fine!!! WTF!!! F'n Ferrari thats what. I put the old battery back in the failed FOB and everything works. It has been a few years now and that damn FOB is working fine. Moral of the story is know your PIN. I rely this story to the OP because sometimes with these cars just need to do a rain dance, rub your belly and pat your head to get the darn things to work. There is nothing worse than Ferrari electronics. Thank the Lord for people like Gobble/Ferrarifobs who can make our ownership lives a little easier.
So at least you know where the Immo ECU is. Time to break out the multimeter and see if it really is a power issue.
