I have made this to control OEM Ford Focus MK1 instrument cluster with Arduino & ELM327
If anyone has Fords SCP J1850 protocol documents, hmu :)
You need ELM327 which actually does J1850PWM and has desoldarable BT module.
Connections:
- Desolder BT module
- Looking at the pcb and pins, where the BT module antenna was pointed up. 6th pin on right from top is ground, connect to Arduino ground. 1th pin on left from top is ELM UART RX, connect to Arduino TX (for this code pin 11). 2th pin on left from top is ELM UART TX, connect to Arduino RX (for this code pin 10).
- Connect GND (pin 4&5, middle two of the bigger row) and 12v (pin 16) to the OBD port. (Lookup picture of OBD pinout, hard to explain due orientation)
- Connect OBD pin 2 (J1850+) to pin 13 on cluster (looking from back, bottom row, most right pin). Connect OBD pin 10 (J1850-) to pin 26 on cluster (top row, most right).
- Connect GND to pin 2 on cluster (bottom row, second pin from left) and 12V to pins 14&16 (top row, first and third pin from left)
- File 'ign-start-drive-dump_notime.txt' has a dump of couple second SCP communication from my 2001 Ford Focus 1.6 FYDA, first 2 bytes are priority, next 2 address of reciever, next 2 address of sender, next bytes are the message and last 2 are checksum, but without timestamps.
- File 'ign-start-dump_withtime.txt' is the same as previous dump, but with timestamps and I didn't move, only revved the engine.
- File 'PoC-old.ino' has old Arduino PoC code where you can set values of Temperature, Speed and RPM. The cluster should react, but will be jerky.
- File 'Speeduino-FordIC.ino' has working code which takes interrupt from Speeduino, Hall-effect sensor for speed and temperature and shows data on the cluster without jerking.
priority to from data(most times first two do not change)
A1 7B 10 02 00 (last 2 by how much, kph/10 at message interval of 50ms)
81 49 10 10 00 (last 2 = temp+40, 16-low|96-middle|a0-max, every 1 second)
A1 29 10 02 00 00 (last 4 = kph*128, needle is off by little, every 50ms)
81 1B 10 25 00 00 00 00 00 (next 6 after first 2 = rpm*1024, next 2 rate of change??, last 2 = throttle 00-b1, every 50ms)
81 88 10 30 01 (last 2 = CEL, 01 off, 02 on, 03 blink, every 1 second)
41 73 10 14 20 (last 2 = alternator, 21 on, 20 off, once)
41 88 10 02 (turns off gear light, once, idk how to turn on (14 gets send also))
no idea what these do:
81 3B 10 04 40 (every second)
41 53 10 3B 10 24 12 24 (once)
41 3B 10 3B 81 03 82 (once)
41 49 60 D0 (twice, these two at the same time)
41 89 60 70 (twice, these two at the same time)
A1 83 60 14 01 4D 00 00 00 (every 130ish-ms, "D" byte changes depending on rpm?)
81 83 60 12 34 (every second)
To get the cluster working, the messages have to be send in such way:
-Every 50ms send:
--odometer, then speed, then RPM, with 5ms delay between each other
-If 1s has passed, the first group send:
--Temperature, then odometer, then speed, then RPM
-Then second group (the next 50ms) send:
--CEL, then odometer, then speed, then RPM