Backup camera broke my fuel gauge?

I'm not a professional, but I'm also not a novice. I am a very experience computer technician, so electrical work isn't totally foreign to me. But I have a weird problem.

I installed a backup camera yesterday. After completing, I noticed the camera didn't turn on automatically. Through a small amount of Googling I found the pin on the wiring harness to my Sony head unit that I need to supply with 12v power only when the truck is in reverse. Then I was able to locate a connector under the kick panel to my left as I'm driving that goes to the reverse lights. Tonight I tapped into these wires and connected them, and as soon as I fired up the truck the backup camera did what I expected.

Hooray! Right? Well, no. Now my fuel gauge shows very low and the fuel light is on, but it's not pegged at the bottom. Still drops a little when I turn the truck off. Also my check engine light is on. And the truck seems to maybe be getting a weird air/fuel ratio or something as it almost "stalls" right after I start it. Seems to idle okay after that, although I haven't yet driven it.

This is really weird to me. Anyone have any idea what I broke? It's *mildly* possible that whatever I did happened last night, but I'm about 99.95% positive the gauge worked after I first installed it and that whatever happened must have occurred while I was connecting the one wire behind the dash to get power to the head unit when the truck is in reverse. There are 26 miles on the trip odometer and the tank should be very nearly full to my recollection.

 

As I look up my issue, the fuel gauge/light thing sounds just like when people's fuel sending unit goes bad. I'm willing to accept that might go bad *just* as I'm wiring up the already-installed backup camera. But that wouldn't also explain the check engine light and the rough starts. I'm gonna have to run an errand soon and I'll know if the truck is actually running poorly or if it's just the starts, and I'll report back here when I know.

 

You have a few different options.

1. Undo what ever it was you did, and see what happens?
2. Get the codes for the CEL

The back-up lights are run by power from the 10A IG1.
Which also powers a few other things, like the the Shift Lock and Airbags and a few other things.
So pulling the fuse to won’t help.

 

I too support this message.

If you are sure you have gas and the gauge was working before the work...

Working correctly.
Something was done.
Not working correctly.

Undo what was done between working and not working.

 

OP, did you splice into the Red/white wire in the driver's kick panel?

 

Thanks, I fully agree with both of you. Undo and test is perfect troubleshooting. I was hoping someone had run into this or knew something specific about the wiring here I might be missing.

Why yes, I did! Why do you ask?

I just got back from my errands, and while I was out my fuel level creeped back up to full where I expected it to be. Meanwhile, after a few starts the check engine light has turned off. I don't know what I might have managed to do, but perhaps it was a fluke? The fuel gauge still sounds just like some specific behaviors people have reported when their sending unit goes bad so I'll keep an eye on that. Not getting the rough starts anymore either.

 

Maybe you FUBAR'd the wires while tapping them, since they are so close.

 

Excellent, this is exactly the kind of thing I was hoping someone would know! Thanks for that. I'll take a close look at the connector and those wires to make sure I didn't leave anything messed up.