Joined: 12 Aug 2013
|Posted: Sat Aug 31, 2013 8:57 pm Post subject: AUX Input trouble on A51804 ('06 Tundra)
|Let me start by saying thanks to this community of DIYers. All this information has been extremely helpful but it seems I am stuck at the moment.
My goal here is to open up an AUX input on my Toyota A51804 HU (2006 Toyota Tundra). I had not seen anyone else work with this HU or vehicle, but I figured the AVCLan protocol would be the same regardless.
I built the standard AUX Input circuit using an ATMega8. I used the simple_avc.hex program written to the chip using PonyProg and a homemade serial programming cable. Program was written and verified without an issue. I had no luck with this so I went into my HU service mode and found the HU address is 190. I switched to using the Avenis aux input hex file (which has 190 for HU address) and reprogrammed the chip. I also double checked my fuse bits.
I still didn't get a CD-Changer icon to show up on the HU. So I went into service mode again and this time the HU did list a device with address 360, but it also gave the following error code:
According to the service manual this means:
The Component does not respond to the ”Diagnosis On Instruction” command. Applicable to only the system where connected components are limited to be used.
I have not built the AVCLan sniffer, and don't have everything on hand to build one, so I'd like to get this working without having to. Has anyone else seen this error and are there any recommendations on what could be going wrong with my communication between the HU and the AUX_Input circuit? I have read about the issue with the lighting control, but there did not seem to be any effect on the circuit whether lights were on or off.
Some other things:
First, the aux input circuit is kind of erratic. Basically I only see the 360 address device in service mode sometimes. At other times, it doesn't show up at all. It seems to show up about 25% of the time. I have some LEDs on RX and TX on the ATmega8 chip (isolated with transistors so they don't interfere with signalling) and while RX just seems to always be HI, TX shows normal activity, except that it is not consistent. On start up, sometimes I get one pattern of TX signals and other times I get another pattern of TX signals. These different patterns correspond to the 360 device showing up in service mode vs not showing up.
Second, my econoreset either went bad or I accidentally got one that is HI-RESET. So I removed it and just put 5V on the reset pin of the ATMega8.
Lastly, I could not find the exact part number for the Can-Bus Transceiver so I used MCP2551-I/P-ND which I believe is compatible.
Any advice you guys have would be greatly appreciated. If I have to build the AVCLan sniffer I will, but I'm hoping I can avoid it. Thanks in advance.