OBDII, ELM327 and 4.2L cars
 

Hi,
Please can anyone confirm or otherwise whether a cheep'n'cheezy ELM327 clone will connect to a late-model 4.2L XKR?

I'm trying to help someone with a car that will not crank after standing for some time, but can't get to talk to the ECM.

Thanks,
Mike

Bear in mind not all ELM dongles are created equal, not least because these days they might not even be ELM327 clones.

On my 4.0 AJ27S engine, the small Bluetooth Classic type dongle simply doesn't work. The larger Bluetooth Classic version works fine, as does the small BLE dongle and best of the lot, the large WiFi dongle.

In other words even if someone else says their dongle works fine, it doesn't mean yours will.

^^^ This

Thanks, guys.
Guess I was hoping for the best, as I tried the three I have (all of which will connect to our four OBD-equipped cars of various makes) but no joy. I don't think anyone in the island has WDS either :(

It does seem likely if you have tried three different dongles and none of them work, that the problem is at the car end. If I were you I would try opening a terminal and communicating direct with the ELM just to see what error messages you are getting back.

If you have never tried this before, have a look online for a tutorial like this one (I searched for "how to open a terminal window with an elm dongle"):-

ELM327 access via Windows Terminal ? twisting-roads.com

Obviously try this on a known working car first to get everything up and running.

I'm sure you already know all this, but if not, ELM dongles do an automatic protocol search, you can force it to use the ISO9141 protocol, with AT SP3. I have found these commands always work (eventually) on my car:-

AT Z
AT E0
AT SP3
AT H0

On my car at least the ECM does take quite a long time to start responding after connection, and will start off with timeouts, BUS INIT messages and sometimes just garbage, but eventually starts working. Enjoy experimenting!

Dibbit,
Thanks a lot for the extra information. AT commands take me back to dial-up modem days :)

yes, Torque Pro shows an auto protocol search when you choose the 'live data' option, but on this car it just keeps cycling through. I'll give the manual processes you suggest a try.

The guy is getting close to scrapping the car, so I'd like to at least try to get him going. Full disclosure:- the local dealership has previously been in there with the parts cannon but gave up and left everything they've been at dangling on the harnesses. This company is beyond egregious.

Thanks again.

The problem with the 4.2 cars is the VID block making it hard to just swap modules around - sounds like a bit of a basket case now. The dealer must have WDS otherwise they wouldn't be able to configure the modules - maybe that's the problem.

The ELM was obviously designed by somebody who remembered the old days of computers - ASCII for the win.

Indeed. If I understand correctly, just swopping a module with another then reversing the change can cause issues.

I'm not at all sure if the dealership has WDS - and even less sure there's anyone capable of using if they do. According to my friendly parts guy there's nobody left who knows our cars, so I was surprised to hear they'd agreed to take a look - $$$, I guess. At least someone had the sense to mark the original & replacement parts so I started by refitting all the original stuff. They'd even disconnected the seat modules..

I'll play old skool terminals this evening to see if I can get any further. There's some life in the car as the hood will raise & lower and lots of ABS-type message reporting.

Onward and upward...

What a horrible story, I suspect many of them will end up on the scrap heap due to issues like this. 🤞 For all those trying to keep them on the road.

There are programs which identify an ELM327's version (or the nearest it approximates).

Then you can try to at least use the most likely to work.

Does sound like a problem with the OBD port. Can you find a non-ELM scanner and try that?

Torque pro gives both the protocol in use and the adapter version, which was 1.5 for the one I've checked:- not an official ELM release, if Wikipedia is to be believed.

I opened the ECM bulkhead container today and found evidence of water entry :( Not deep enough to reach the ECM, but it's had a go a the module underneath. The ECM internals looked fine:- I'm amazed that there is no sealing on the lid.

Possible. I forgot to take my multimeter today so couldn't do any continuity checks.

I've been looking for an excuse to buy a Mongoose adaptor...