Can a fuse blow without looking blown?

I was putting in some new switches over the weekend, and may have overloaded the dash light circuit momentarily in the process (I also may have created a short somewhere, gotta pull the dash panel back off and check the connections).

One way or another, my gauges are now not lighting up when the headlights are on. It's behaving exactly as it would if the "gauge" fuse were blown, but I pulled the fuse and checked it, and it looked fine (I got too lazy to continuity test it or replace it). I also pulled and checked pretty much every other 15A or lower fuse in the two blocks and nothing looks blown on a visual check.

On a tangent, does anyone out there know why a Pre-Runner would have a fuse installed in the "4WD" spot? I do have the TRD/OR, so is the locker maybe on that same circuit?

 

Yes it has happen to me several times. The only way to be sure is to test it with an ohmmeter.

 

Yup, hard to tell sometimes. If you can't test it, you can always switch it, they're pretty cheap parts.

 

OK, thanks. I could've tested it, but just go too lazy to reach over for the DMM that was on my passenger seat, and would've had to walk a 30 foot round trip to get the replacement....

I was touching wires together trying to figure out which line did what for swapping in an after-market 2-LED switch. I had the ground figured out already, so I didn't do a straight-on short, but I did at one point try to power the fog lights off the dash gauge circuit (I've got LED bulbs in the fogs, but they may have some built-in ballast/resistors since they're designed to be headlight replacements), which easily could have over-drawn the 7.5A circuit.

 

Also, the upper LED's on the switches aren't working, either and they're not powered off the gauge circuit (which is why I think I shorted or mis-connected something in the course of putting the wiring together)

 

The gauge fuse was fine, based on the reaction from the truck when I pulled it with the power on. Turns out the switch/console lights are on the tail light fuse which it never occurred to me to check.

Thinking about it though, it makes a certain kind of sense since the driver can't see the tail lights when driving but can see the dash. It'd make a lot more sense if it were widely known, though...

 

The gauge fuse was fine, based on the reaction from the truck when I pulled it with the power on. Turns out the switch/console lights are on the tail light fuse which it never occurred to me to check.

Thinking about it though, it makes a certain kind of sense since the driver can't see the tail lights when driving but can see the dash. It'd make a lot more sense if it were widely known, though...

 

Does your horn still work?

 

haven't tried it, but the "Tail" fuse was definitely blown and replacing that got the switches to light up fine. I think the horn has its own fuse (can't remember if it's in the cab or under the hood, though). Now I need to get my harnesses run and my fuse block/relays installed for all the gadgets these switches are going to run...