Curious "B" fuse (heater blower, wiper) question

[stuartrubin]

So, after a ton of things went wrong at my mechanic's today, this one was most curious. Suddenly,perhaps after fishing around for a trunk release cable, the car would not stay started once the key was released. That is, it would crank and if you kept the key turned hard to the right, it would run until you let it back. After some searching, saw that the "B" fuse was blown. Once replaced, things worked fine.

So, the question is, why would the fuse which controls the heater fan, windshield wipers, and washer pump have anything to do with the ignition?

Thanks

[bradartigue]

Sounds more like fuse I was blown...you sure it was B? The box runs L to A (it is mounted upside down).

If it was indeed B then I blame a ground. Because it's always a bad ground.

[stuartrubin]

I'll double check for the benefit of the class, but let's assume I was looking at upside down and I was seeing the "I" fuse.

That one protects some gauge lights, and the "electro-magnetic fan clutch" (per the Hayne's manual). How could THAT keep the engine from running? I appreciate that there could be a ground problem, but I'm still seeing how the problems are connected.

Brad, thanks always for your insight! Someday if I'm ever wherever the heck you are, I'm buying beers.

Stuart

[spider2081]

pretty sure Fuse A is closest to the steering column

[bradartigue]

Per the comment "pretty sure Fuse A is closest to the steering column" - it is.

Fuse A is closest the column. It runs from the highest letter to A, door to wheel. ---->

On your car the "I" fuse may also control the remnants of the seatbelt interlock system and controls that would prevent the engine from running if unpowered. Which is the only reason why I brought it up.

[stuartrubin]

Whoa, wait a second: you're saying that on my car, that BARELY had seatbelts in the front when I got it (and none in the back) has an interlock (which has been disabled, apparently) that keeps the engine from running if not latched? That's some pretty progressive, if not totally annoying, safety engineering! I am totally shocked.

I'm fine with the safety feature considering that it was 40 years ago, but I am still surprised that there was no redundancy or override on this. Was there a way to override this? Were you just screwed if the fuse blew?

I'll chalk this up to FIAT trivia...

[spider2081]

I believe the seat belt interlock relay was installed between the ignition switch and the starter solenoid. If the interlock circuit was bad the car would not crank at all as the starter solenoid would not pull in.

[bradartigue]

I believe the seat belt interlock relay was installed between the ignition switch and the starter solenoid. If the interlock circuit was bad the car would not crank at all as the starter solenoid would not pull in.

You're seeking precision in an imprecise system. I'm saying the only thing interesting on that fuse is that it has the devices may be one blown. Nothing else.