After playing with AI2 for a couple of days and making simple apps to test different features I wanted to try to make a useful tool. I decided on an OBDII scan tool for my Blazer. I was able to get a working prototype in just under one hour.
I used a common ELM327 Bluetooth adapter I got for $12 a couple of years ago.
Since it was rainy most of the weekend I used my ECU simulator for most of the design work.
I started with a simple interface.
I added a terminal screen for oddball queries.
I use a drop down for direct addressing to each module to get error codes. No parsing or DTC lookups yet but I can read the codes from the raw data.
I took it outside and tested it on my truck. Sure enough it showed an ABS code my Innova scanner doesn’t see.
the ABS module shows one code “42 21” which translates to a “C0221”. You just remove the 2 high bits and convert that using this lookup table…
‘A7 A6 First DTC character
‘– — ——————-
‘ 0 0 P – Powertrain
‘ 0 1 C – Chassis
‘ 1 0 B – Body
‘ 1 1 U – Network
The code says the right front wheel sensor is open. It’s not broken I just have it unplugged since I was working on the brakes. At least I know it works better than a commercial $50 Scanner does…..
I have to refine it and add DTC parsing.