OBD-II UART directly to engine computer

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1

Hello,

I’ve had trouble hooking the OBD-II UART to a 2004 Ford Escape PCM(engine computer), not installed in the vehicle.

After connecting the powers, grounds and SCP(J1850), there isn’t any communication. More puzzling, the atrv command shows 0.4 volts. The measured the voltage is 12 volts from a regulated power supply. The OBDII board works as expected in my car.

Has anyone directly hooked a PCM to the OBDII board or have any ideas? Thanks.

https://www.sparkfun.com/products/9555

Connections:

Pin Function

3 Ground

23 Ground

24 Ground

25 Ground

33 Ground

51 Ground

57 Ground

103 Ground

55 12 Volts

64 12 Volts

71 12 Volts

97 12 Volts

15 SCP-

16 SCP+

2

I found my mistakes. My pinout was for the connector(female end) not the part(male end) :roll: . I had everything mirrored. After that, I had to apply power to pin 55(power at all times), wait a couple of minutes, then apply power to pins 71 and 97. The PCU needs to boot-up before power is supplied to the PCU power relay pins.

atrv command now reads the voltage as 0.7 volts, but the unit responds to commands.

One last note, the “THIS SIDE UP” warning applies to installation, not orientation. So I had it upside down and backwards.

Ref:

http://mustangforums.com/forum/4-6l-199 … er-up.html