how did i do that again?

car radio

Intro

So a year ago, or maybe longer, I started getting these weird glitches in my cars head unit.

I currently drive a Hyundai Accent 2013, which had the default head unit from its manufacture.

I had left my house when suddenly I thought I had a call from my partner - when in fact the call was initiated by my car to my partner. I disabled the bluetooth connection to my phone and noticed that my head unit was displaying information as if receiving button presses from my steering wheel.

I did some tinkering a few weeks later - and after some frustration trying to remove the air-bag from the steering wheel so I could disconnect the controls - I decided to try from the head unit side and found this website and the CHARM project, which seems pretty cool. It had a guide on the exact head unit I was working on (Hyundai PA710S). I removed the steering wheel control (B4) and steering wheel ground (B17) from the OEM harness adapter and taped them back against the insluation.

This seemed to improve things for a while, the steering wheel controls I had mainly used for volume control and I could listen to music again. However after a while, near the start of this year, my head unit went beserk and started muting, unmuting, turning off and on, having 100 button presses every second.

After some research and a friendly chat with a mechanic while dropping off my partner's car at a crash repairer, it was becoming more likely that the issue was actually with the head unit and nothing to do with the connection.

Preparation

I started off trying to work out what I would need to replace the head unit with an aftermarket model. This was a combination of a lot of Googling (somewhat helpful) and LLM usage (useful, but flawed, more on that later).

Additionally the choices in this guide were made because I didn't want to solder anything. Not that I can't, it's just annoyingly tedious.

Data and parameters

So if you know me you know I need to know what the inputs, outputs, and parameters are of any given task, which the modern world seems ill-equiped to provide to me in most cases. This is also the reason I wanted to start this blog because of the number of random blog posts that have assisted me in my esoteric knowledge gathering over the years.

So for this task I will outline what I EVENTUALLY figured out I needed to complete this task. However I will expand on the difficulty journey it was to consolidate all of this together.

Parts:

Random knowledge:

Process

The next are technically steps easy, but also involved me having to go and buy the OEM to ISO adapter since it wasn't specified in any of my research.

Steps:

  1. Turn off car and disconnect the ground cable from the battery to prevent injury.
  2. Remove the existing facia dashboard carefully, but requiring some elbow grease.
  3. Remove the AC vents and cables from the existing facia dashboard and attach them to the new kit.
  4. Undo the 4 screws holding in the head unit. For some reason the top left screw I had to tear out of the housing since it was so tight.
  5. Remove the mounting brackets from the sides of the old head unit and attach them to the new head unit. This was actually kind of a pain since the sides of my new head unit didn't fully match the brackets so it took some trial and error to actually accomplish this.
  6. Attach the OEM to ISO adapter to the OEM plug from the car.
  7. Connect the ISO to head unit wiring harness adapter to the OEM to ISO adapter.
  8. Connect the head unit wiring harness to the back of the head unit.
  9. Re-assemble the head unit into the dashboard and insert the new facia kit.
  10. Re-attach the battery to test the radio before cleaning up.

Conclusion

Cars are more annoying to fit together than PCs and anyone who says otherwise needs to do both. However car parts are far cheaper, especially for adapters.