Caterham OBD or Can

[Tboner]

Question is the ecu diagnostic plug on the Caterham K series a Can or OBD type plug ?

[CharlesElliott]

It's OBD - but the data refresh rate will be so slow as to be effectively useless (that's the OBD2 specification's fault, not RTs)

[Tboner]

Charles i did try to call you to ask the question thought you may know

Damn thought it would solve a lot of issues with wiring up using the new adapter they have now issued oh well looks like stick with the dl1 and dash 3 till the closed season then.

Cheers

Paul

[CharlesElliott]

If you limited it to one or two sensors it might just about be acceptable. But the data on the K series available over OBD is fairly limited. RPM, MAP and temperatures are about the only things you might want to log. Unless short term fuel trim is of interest

[Tboner]

Thanks for the info Charles

[Tboner]

really looks like the £150 cable is not worth the money to save the time involved in wiring up 2-3 items

Mind you i wonder if the port logs lamda sensor and fuel pressure or even throttle position sensor which you could use for diagnostic off the data logger for fault finding ?

[CharlesElliott]

It does output lambda voltage - but on a narrow band lambda it is oscillating between two voltages quickly and, to be honest, too quickly for the OBD data rate. Also the lambda isn't really used when the throttle is wide open!

Fuel pressure - no

TPS - yes; probably the most worthwhile, although data rate may still be an issue.

Just to be clear, OBD doesn't 'log' anything, you can just read it in 'real time' from the port.

[Tboner]

yes real time off the port to the DL1 was the idea for data use but would have been nice to get RPM from it for both the data logger and the dash3 shift lights, the dash3 i just wanted for accurate lap and sector times with predictive in real time , along with shift lights.
Are you running the firware on your DL2 dash with predictive lap times ETC ?

[CharlesElliott]

No, I run DL1 in acquire only as I don't have any of the Dash products.

[Support]

We have found out today that the k-series engine running the Gems ECU is NOT OBD-II compatible on all vehicles. Although it may well have the right connector on it it actually uses different pins and a different protocol to the real OBD-II interface. If your connector has +12v on pin 16 and gnd on pin 5 then it most likely is OBD-II, if it doesn't have these then it won't be and the interface won't work.

The update rates on OBD-II are about 10Hz at best, a direct connection to the logger is always better where possible.

Regards,
Martin

[CharlesElliott]

Do you mean MEMS (which is the K series ECU)?. I have an OBD2 reader which works on the Caterham so I know that my Caterham, at least, has an OBD2 compatible output

[Support]

I thought I meant MEMS, but after have a read it could have been GEMS. Unless somebody else has some concrete evidence on this I suggest you just take care. If you want to confirm if it has an OBDII compliant port or not, check that it has power on pin 16 and ground on pin 5. If not, it is not OBDII compliant.

Martin