Mystery fuses or MFU or just plain old curse?

[paxton]

So I made the mistake of installing a new radio.

The radio requires two power sources, one always on and one switched. I found the correct two out of the connector and wired them and ground. When I turned on the radio, I got nothing.

I took everything out and put it on my bench. I hooked both power wires to my power supply set to 12v and everything powered up fine.

I wired it back into the car and again, nothing. I tested the switched power and it was 12v. I tested the always on power and it was 12v. Then I checked it when the radio was powered on and it would drop to 7.3v. I don't know why that would happen.

I ran a fused line back straight from the battery for the always-on power. The only connection it has is to the radio. Sure enough, I didn't get a voltage drop and the radio works like a champ. When I was soldering the wires, however, I shorted them and blew the fuse in the wire from the battery. I replaced the fuse, finished the wiring, and the radio works great.

But...

Now my dome lights don't work. And my turn signals don't work. Wipers, lights, interior dash lights, etc. all seem to work. I checked all the relevant fuses and they were all good. But the dome lights and turn signals, from what I can tell, don't share a fuse anyway. Which leads to the upstream common component: the MFU (which I have never dealt with before).

Did I fry my MFU when I shorted with the power line straight off the battery? Is there something else I can check?

Thanks!

 

[robertf]

does the hazard switch work?

 

[paxton]

does the hazard switch work?

Yes.

See this older post for someone with the same exact issues:

https://discoweb.org/forums/showthread.php?t=86601

 

[robertf]

is the red/brown wire unhooked? should be purple and green/orange wires for your power

 

[paxton]

All clock wires are connected. Tried a different clock with no success. The clock will occasionally work but not for long and will not come on next time. It's random; 90% of the time it does not work.

Dome lights and turn signals never work.

I might have shorted the 12v always-on with the switched power line -- not the black ground. This line would would have 0v when I shorted it,because the key was off. Maybe that will help diagnosis.

I ran the vehicle and didn't have any issue starting or running.

I'm not at the truck right now so I'll have to check. I know I picked the right two wires for power (switched and non-switched). No issues until I shorted them when soldering.

 

[robertf]

im talking about radio wires. dont hook up the illumination wire (red brown) it causes problems.

 

[paxton]

Gotcha. IIRC, I used the wire in the connector right next to the black ground wire for 12v. And I used the one next to the black one going up one position for the 12v switched power. Again, IIRC. The one didn't work so I ran a line from the battery for it, but the switched source is the same.

IIRC.

 

[robertf]

sounds like you blew sat 2 fuse 6

 

[paxton]

sounds like you blew sat 2 fuse 6

OH MY DEAR GOOD GOD. It was fuse 6. Thanks so much.

I'm such an idiot. Of course the fuse that controls the trailer lights would be the one to control the clock and the interior lights. Of course. :banghead:

Thanks Robert!

 

[fishEH]

Nice job, Robert! Way to improve the sad state of the Tech forum!
Now that his problem is fixed we can make jokes about his sexuality, right? :ack:

sounds like you blew sat 2 fuse 6

OH MY DEAR GOOD GOD. It was fuse 6. Thanks so much.

I'm such an idiot. Of course the fuse that controls the trailer lights would be the one to control the clock and the interior lights. Of course. :banghead:

Thanks Robert!

 

[robertf]

Thanks Robert!

no problem, now enjoy your shitty aftermarket radio

 

[paxton]

no problem, now enjoy your shitty aftermarket radio

I appreciate that. I'd rather have your product, but the PO had already pulled the amp and connected directly to the speakers, and I'd have to undo all that.