OBDII Pods – ECU / Immobiliser / Key Pairing – And Much More

The Problem

I’ve recently started sending out modified remappable MEMS 1.9 ECUs. It’s not easy to send these in a “plug and play” state where they will automatically pair with an immobiliser when they see one, so I needed an easy way for people to be able to pair them with their existing immobilisers.

It is possible with my MEMS Mapper and Lucas 5AS tools, but you need a PC and various cables and some people didn’t have laptops / weren’t particularly comfortable with the PC applications. So I needed something really easy.

I also get regular requests to pair standard ECU, immobiliser and key fob sets for people.

The Solution

So I designed these …

They do the job with just one button press.

OBDII Pairing Pods

Of course, me being me, I took the thing a whole lot further …

They work with the MEMS 1.9 ECUs as originally intended. All you need to do is:

· Make sure the ignition is on and the immobiliser is disarmed.

· Plug the pod into the OBDII socket.

· Press the “1.9” button.

· It will beep and the yellow “Run” LED will come on, telling you it’s busy.

· After a few seconds this should change to a green “OK” LED … meaning all done!

· If you get a solid red “Err” LED it couldn’t communicate with the ECU for some reason.

· If you get a flashing red it got an error code back from the ECU … it flashes in groups and different numbers of flashes mean different things so you can look up what was wrong.

They also work pretty much exactly the same with MEMS 2J and MEMS 3 ECUs. Just press the “2J/3” button instead.

They will also pair key fobs with a Lucas 5AS immobiliser. Slightly different this time:

· Press the “5AS” button.

· Wait until the yellow LED blinks and it beeps again to tell you it’s ready for keys.

· Press the lock button on each key fob 8 times or more (on a Rover the horn will sound briefly after each key isa learned, on a Caterham unfortunately there’s no feedback).

· Then press any button on the pod to tell it you’re finished, the green LED will come on and it’s job done.

If anyone wants to borrow one, just shout. You can buy one off me if you really want, but unless you’re working with these cars on a regular basis, they’re the kind of thing you only need once. So long as they come back safely I don’t mind loaning them out. Just to be clear, these will work for pairing up ANY of these ECUs with immobiliser and key fobs, not just my modified remappable ones. So if you are replacing an ECU and immobiliser and need them pairing up, or if you want to pair a replacement key fob, these will do the job very easily.

Other Pods

But I designed them as completely generic devices with a few goodies inside …

They’re really general-purpose OBDII Swiss Army Knife toolkits.

They’re built around an Arduino Pro Micro which allows easy programming in C. This uses an ATMega32u4 microcontroller, which means they have TWO serial ports, one used to talk to the OBDII port and one to the USB-C connection. I’ve written a library of functions which let them communicate with all of the supported devices. For MEMS 2J/3 they talk in properly formatted and validated ISO14230 / KWP2000 protocol, so they can easily handle diagnostics sessions, seed key security routines etc. For MEMS 1.9 they talk ROSCO protocol, and for Lucas 5AS they talk modified ROSCO with the odd inverted L-Line reply protocol (the L-Line inversion is done in discreet hardware, presenting a standard UART signal to the microcontroller). The on-board discreet electronics can transmit on K-Line, receive on K-Line and receive inverted L-Line through any of the OBDII pin combinations used on MG Rover and Caterham cars.

The three buttons, three LEDs and beeper are under the control of the microcontroller, so can be used to implement a range of simple user interfaces.

And they have a 2 Mbit serial EEPROM chip built in on the board. This means they could be programmed to do things like:

· Record live data logs from MEMS 3/2J/1.9 or Lucas 5AS. The logs could be downloaded to a PC over USB afterward.

· “Smart” data logging … watching for a given fault condition and then logging for a given time period.

o Which could use a rolling log to record the bit before the fault happened as well as the bit after.

· Read and store the firmware and map from an ECU. The EEPROM is large enough to hold complete read of any of the ECUs.

· Write a new firmware and map to an ECU (remote mapping delivery).

· ECU deep cloning.

· OBDII map switching.

· Probably lots of other things I haven’t thought of yet! Let me have any bright ideas.

Rev 2.0

The design above is a prototype “Rev 1.0”. I’ve since designed a production “Rev 2.0” which, amongst other minor enhancements, has robust external 5V regulator on the board, as I’ve found the tiny internal regulators on the Arduino board to be a bit fragile, even when stepping the external supply down from the nominal 12V to 9V externally first. Having said that … I’ve had ONE fail in these devices, and that was custom programmed and trying to run a brute-force seed-key crack on another ECU and had been running for 10 days x 24 hours flat out at the point where it failed, so it was getting a good hammering!

The Rev 2.0 boards are currently in production in China. Rev 1.0 and Rev 2.0 boards can both run exactly the same firmwares.