First you need to be able to find the port that the ELM327 cable uses on your PC. In Hyperterminal set to 38400baud, 8 bits, no parity, 1 stop bit (otherwise called 8N1)
Then pick a port number and 'connect' to it.
The ELM327 (search on Google for 'ELM327 datasheet' if you like) uses AT commands ot configure it. After connecting with HT type in ATZ<return> and see if you get a reply, like 'ELM327 v1.4b'
Keep selecting ports until you have such a response from the ELM327 cable (Which doesn't need to be plugged into the car at this point)
Once you have the port, then you need to configure the ELM327 chip in preparation
"The following commands do not affect the car at all
press return after each command, and wait for the '>' ready prompt before entering the next command
(NOW PLUG THE CABLE INTO THE CAR, IGNITION ON & ENGINE OFF)
ATZ - causes a reset of the ELM327
ATS0 - (digit zero) to turn off running spaces
ATE0 - (digit zero) to turn off ECHO
ATL1 - to turn on line spacing
ATSP5 - set protocol to 5 (CAN bus)
Just for fun (as a test)now type ATRV and the ELM327 will return the system voltage it measures for itself.
If you've got this far and have a voltage response message you're good to go.
(Note that at this point yoiu haven't done any communicating with any ECU, this has all been about setting up the ELM327 chip so far)
The following commands talk to the ECU using nothing but mere standard OBD commands which every test device issues, this isn't even like hacking, you are merely manualising a usually automated process. The response from the ECU should not be 'error' !
ATSH8110F1 - (digit zero) to set the header of the messages you send on the CAN bus so that the correct ECU knows you are speaking to it.
ATFI - perform a fast CAN bus initialisation (should not respond with error)
3107 - (digit zero) Mode 31, PID 07. Means begin a functional test of the DPF (which involves resetting all DPF related parameters first)
A succesfull OBD response will begin with the first digit being the same as the first digit in the command you sent, plus 4. Sending 3107 will produce a positive response of 7107 (somewhere in the returned string which you will see on screen)
To find out if the command has reset the dpf counters (and therefore worked) either hook up multiecuscan OR easier yet, send the following command
21CD - mode 21 PID CD return the value for dpf clogging. The 6th and 7th characters should be zero (sometimes an extra 2 characters might be appended to the response of 21CD, (which will begin with 61CD ), but at around the 6th or 7th character position you'll find a pair of zeros if the command is successful
Now you can disconnect safely. Remove the key, wait for the steering lock to come on, and you're back in normal operating mode again.
A couple of other useful commands....
After getting as far as sending ATRV, above (after following the first initialisation commands), simply sending '04' will clear all error codes and reset the CEL/MIL light if it is on. '03' will return fault codes which have brought on the CEL/MIL light, if it is on, and '07' returns any pending fault codes (which might be present when the engine is running, but which aren't considered serious enough yet to bring on the CEL/MIL)
All I can say is be careful when typing 3107, but to be honest I've hunted around that range of modes and PIDs and haven't caused anything untoward to happen.
In brief, if you just want to try resetting the dpf the quickest possible way, the 5 successive commands to use are as follows
(wait for '>' or the ELM will give you a 'STOPPED' message if you send messages too quickly for the ECU )
(And 21CD to get the clogging value if you don't want to use multiecuscan to read it out)
If anyone tries it on a 2.4, please report if the '3107' command does/doesn't affect clogging % of your dpf.