Which BRZ head unit model? (find the number printed on the front, as well as the numbers on the mfr's sticker on the top)
Is this really in a Toyota MR2, or do you need to update your profile? (in other words, what car year and model is this?)
Subaru BRZ Fujitsu Ten HUs check for the camera each time you turn your key from OFF to ACC. The HU will decide you don't have a camera (and thus disable the camera function) if it does not see the camera video signal during that test.
That could be caused by no video signal from the camera, which could be due to any of these reasons:
- Dead camera
- Bad connection from camera video signal to HU
- Bad connection on power lead from HU to camera
The 6 Volt camera power comes directly from the HU to the camera -- there is no separate fuse.
Narrow down the location of the problem:
- Check that the camera provides a good video signal (temporarily connect it to the composite input on a monitor or TV). Initially leave everything else as it was, including the camera powered from the HU. If that doesn't work, power your aftermarket camera from 12V. Then try 6V (using batteries).
- Connect a known good NTSC composite video signal to the HU's rear camera input, and verify that it displays that image. Use anything handy (digital camera with appropriate cable, camcorder, game console, DVD player, VCR, etc.).
- Verify that the OEM HU supplies the 6V power. When the camera is not working or disconnected, the HU will only do this for a few seconds immediately after you turn the key from OFF to ACC.
See
this guide for more information and tips.