2013 FRS wont start unless battery is disconnected first

[KN0W]

Hello, This week I was trying to wire in a reverse camera.
Installing the camera went fine, wiring it did not (somehow).

For the reverse signal wire -
Basically I sent a wire from pin2 of the 28 pin connector behind the HU (was empty on my car) down to the driver footwell to a fuse labelled BK/UP LP 7.5a (Back-up lights)

12V for cam -
Temporarily just using some 12V that was on when the engine ran going to HU I did confirm the camera turned on when I asked the HU to open the camera Pretty sure it was for the amp or front speakers

GND for cam -
wired into a GND wire in the trunk there is a connector right under where the bung that connects the trunk lid wires to the main body I used a GND wire in that connector.

So now I will list what the sequence of events was right before the computer decided that the engine should not be started anymore.

I pushed the start button and everything turned on normally.
I had forgotten to connect my temporary 12V+ wire for camera power so I switched the car off.

Connected red 12V+ and the purple REVERSE wire on the back of the HU (also grounded a lime green parking SW that my Kenwood HU has)
Note red to red for power, purple to purple to pin2 on the 28 pin connector on the back of the HU harness (this is blank on my 2013) I then ran a wire from the then blank Pin2 to the driver side footwell where there is the 7.5a BK/UP LP fuse, I thought this would be good to use as a on/off for the HU to know when to automatically swap to the camera screen.

Then I tried to turn the car back on. fuel pumps go, lights go on, beeping because the door is open no starter though.
after a few frustrating minutes of retrying this I also noticed the PND lights were not on on my shifter and the cluster was also not displaying drive mode.

I then checked the only fuse I had messed with, found it to be blown replaced with the 1 good spare from engine bay fuse box.

car still will not start, but now I have the PND light indicators back and the car is only beeping because the door is open NOT because it doesnt know what gear its in. (I have at this point NOT reconnected my "reverse sensor" into the fuse since I assume thats what blew it somehow/)

After this I plugged in a scanner, cleared the codes and retried. no change starter doesnt go on.
I checked the codes again and the only one thats there is U0126

Here is a list of the codes I had after the car didnt start the first time
C1278 Steering wheel angle and 2 signal faulted
C1277 Requested Torque Signal Circuit Malfunction
C1276 Park Brake Actuator Assembly Switch Applied Circuit Short to Ground
C1275 Solenoid Relay #1 Circuit Short to VBatt
C1274 Solenoid Relay #1 Circuit Failure
C1273 Motor #2 Input Circuit Short to Vbat
C1272 Motor #2 Input Circuit Failure
C1271 Motor #1 Input Circuit Short to Ground
P0851 Park/Neutral Switch
U0126 Lost Communication with Steering angle sensor module (the only one that stays after unplugging battery and then starting car)

Hopefully this is enough detail to help, I can provide more and photos for clarification
sorry about the wall of text.
I hope I can revert the damage. Im concerned about having to replace that sensor since I dont have techstream to set it up again, or doing some damage to a computer that will cost a lot to replace. Im pretty sure its not that since this was supposed to be a fuse to the reverse lights, but who knows.

[KN0W]

Update

I decided since I could get the car to start by disconnecting the battery then plugging it back in that I would go get a drink.

probably 40mi there and back

I got back into my garage and was able to shut the car off and then it did actually crank and come back on.

My friend says his Audi will also give a steering angle sensor error till he drives it for a bit. so maybe thats what was happening here.

I guess now I need to re read a bunch of the HU install threads and see if anyone was able to do an OEM like wiring job to get Reverse sensor and Parking sensor wires from their origin to the Aftermarket HU and camera. I am rather surprised this worked since I was at it for about 4 hours. but this is good, now I can buy more fuses and a multimeter and experiment.


If anyone has any good ideas for where I can pull a reverse sense signal from to trigger rcam on and off that would be great. my aftermarket HU has a lot of the wiring but it assumes I had those OEM parts (the harness fits all model years from what I can tell because it also has steering wheel button support if I had that, and the reverse camera. )

[FR-S2GT86]

Take no offense from this but, from someone with years of experience in car audio and other aftermarket mobile electronics installation experience, I can tell when someone else doesn't. My advice for you specifically:

Hire someone that knows what they're doing to complete your installation for you. Please.

[KN0W]

Originally Posted by FR-S2GT86

Take no offense from this but, from someone with years of experience in car audio and other aftermarket mobile electronics installation experience, I can tell when someone else doesn't. My advice for you specifically:

Hire someone that knows what they're doing to complete your installation for you. Please.

No worries.
However I really cannot pay a competent person to hook up 12V+ Ground and a sense wire for me right now.

so I will continue on to just buying a multimeter and looking for correct wiring diagrams. And honestly it works if I just hook up the 12v and ground but I want it to switch automatically. and I dont want to cut wires in the middle. thanks for the advice but I cannot follow that for this.

Once I figure out a nice solution for me If I remember Ill post back here so if someone has the same situation they can just copy.

[FR-S2GT86]

I hope you figure it out. Good luck.

[Wally86]

Originally Posted by KN0W

No worries.
However I really cannot pay a competent person to hook up 12V+ Ground and a sense wire for me right now.

so I will continue on to just buying a multimeter and looking for correct wiring diagrams. And honestly it works if I just hook up the 12v and ground but I want it to switch automatically. and I dont want to cut wires in the middle. thanks for the advice but I cannot follow that for this.

Once I figure out a nice solution for me If I remember Ill post back here so if someone has the same situation they can just copy.

There's a pink wire in the trunk that feeds the reverse light. If I was looking for a 12v trigger wire for reverse, that'd be it.

There's even a ground bolt and a couple of wires right next to it.

I have a lot to say but I'm going to just hope you get your issues resolved and the car fixed.