Lexia can read DTC's but not erase - bizarre fault!

[Rhothgar]

Hi all,

Bought a full chip the other day from an Ebay seller. Very good guy. Paid a little over the odds of what some others were charging but their support looked good if ever I need it.

Plugged War Horse in and read fault codes. However, I get no comms when trying to delete.

Done a bit of reading up about KWP2000 protocol. Correct me if I am wrong. Line L ISO bus initiates the wake-up call to ECU and Link K ISO bus is used to transfer data. This, I assume, is a two-way transfer channel.

I could send some AT commands via ELM327 (if I knew what I was doing) to erase codes. I have found a very interesting 122 page KWP2000 confidential manual online which is for Dodge, Jeep, Chrysler, Mitsubishi, Mercedes and Smart and defines all the headers and the like. Just wondering if anyone has ever tinkered with AT commands to sending commands and requesting data from an ECU.

I have a MPPS cable from reading ECU files and could use that but with PuTTY to transfer the commands and get responses from the ECU.

Failing that, I am trying to get my head around WHY I can read fault codes but not delete them.

Wondering whether these codes are written to the EEPROM on one channel but read via another?

Maybe software in ECU is corrupt, in which case, if I can grab a valid EDC15C2 file from one ECU would I simply stick that in a particular Lexia folder to them be able to transfer the file to the ECU? I assume this is telecoding and it is available in v.7.57 Diagbox.

[mickthemaverick]

Out of interest Roger have you tried resetting the codes with a simple code reader?

[Rhothgar]

Out of interest Roger have you tried resetting the codes with a simple code reader?

I did but they won’t even read.

It leads me to wonder if the fault codes are historic or current? I’d imagine Lexia is reading them when connected but if the codes have never been erased then they would subsist in the memory.

I am tempted to try sending AT commands but maybe I should plug in a known non-working ECU on first and see if the codes are different and if three can be erased. This MIGHT rule out the DLC connector wiring I was worried I had damaged.

[Rhothgar]

I think I may have got one step closer. The wire where the terminal pushes back in the DLC instead of engaging properly with the OBD2 connector is Pin 5 which is signal ground.

I’m entirely sure whether that controls active reads at the moment or live data signals.

Some of the Lexia faults I have state 50degC air temperature. I had a faulty NTC resistor in one mirror which got smashed and off and then replaced so I reckon those codes are from before that mirror was replaced.

I probably did the damage to the DLC terminals afterwards.

I will get to the bottom of this. Hopefully someone might be able to chip in with some sage advice.

[Rhothgar]

Out of interest Roger have you tried resetting the codes with a simple code reader?

Just tried and a simple ELM327 OBD-II reader does not even report any codes.

I set it to ISO-14230-4 5k baud which I know is the protocol from having plugged it into Bosch KTS590 before up at my mate's garage.

I'm just wondering now if I should actually spend time installing the Diagbox downloads that the seller provided and wondering if this is something inately different with the full chip Lexia Rev C that requires a 'different' version of 7.57 Diagbox.

In PSA Interface Checker, it comes up as Rev C.

And it reads and finds all the ECU's bar the aircon diagnostic.