New to VX Commodore PCM ECU issues.

[pman92]

I meant set the PCM up on the bench (the ecu), not the BCM.
This involves basically removing it from the vehicle. Get yourself a pin out diagram. Connect up all the powers and earths so it is powered up, but dont worry about connecting up sensors or outputs etc. And then connect up the serial data pin to your interface, and power and earth to your interface. Or just wire up an obd plug etc.

The ALDL network talks directly with whatever you are speaking to. All the modules are wired in parallel directly to the diagnostic pin. Although I think the BCM has a relay that can open and "isolate"/cut off half of the network from the other half, the PCM is always wired directly to the diagnostic port.
It doesn't go through any other modules or processors. When you send a message to device F7 and receive no response, it was because F7 didnt repond. Likewise if F7 did respond it was the processor in the PCM say that directly wrote that message to the data bus.

[VL400]

If i have the seed and security keys from it (about 2 years ago), and VATS can be turned off and on via the TunerPro software. Surely there must be a way of doing the same, even if it involves doing so at the lower level of direct HEX coding at the EEPROM address the data bits are located? By changing the data bits at the required Address (hex) locations, wont that then allow for the two devices BCM PCM and ECU to all see each other as being originals and then work together?

I cant (as i obviously dont know enough yet) see how come I cant say send a sequence of code or codes, via the ALDL interface. That would say let me re program the address (hex) of say 4657. Making those 8 bits or there of, become values like 0011 1010. Does that make possible or even logical sence? Or am I so far off the matk here?

I understand it would make for a very poor security system should it be that easy to do so. But keep in mind, I hold the security key and seed key already. Not something most would be able to obtaiin if they were of a theiving nature.

The PCM does not have the means to change itself by just sending a command. One reason being is flash chips can only change a 1 to a 0, not the other way around. So before doing anything an entire sector needs to be erased which sets all bits to a 1, the cal is one such sector so for a single bit change it needs a complete sector rewritten. Along with that the normal code the PCM runs to control the powertrain does not have this erase or write code in it. The tool, like flashtool, needs to upload code for the PCM to run from ram so it does not get erased during the reflash process.

Anyway, the short of it is you cannot change the memory location over aldl without sending massive chunks of code. Even if you could communicate with the PCM.

If you did a bin read and didn't clear the registers when given the option, post me your PCM with a return post bag included and PM me the bin (Actually do that first and I can check it). I will recover it and return it.

[madmaxisback]

I have had one PCM that the flash failed 99% of the way in because the lappy hung up. It wouldn't detect via Flashtool, car wouldnt start or even make attempt to activate starter etc.

Thought it was toast, but I got the Tech2 (Hantech clone) and l linked PCM/PIM and then disconnected battery/reconnected and it started like normal. Like I said earlier, I would try "borrow" a tech2 and see if this helps first mate.

If you do have a copy of the stock BIN you can clone with any "used" VX or VY PCM easy following the steps in links I posted earlier to VL400's VX/VY PCM Flash guide. (However I think you might not have this copy - bugger)

Otherwise just post PCM to VL400 and he will try and save the day once again.
(He wears a cape you know mate - total legend!)

[JohnDee68]

Hi Yoda69,
The program which i did origionally download the bin file with (Flash Tool) doesnt allow to connect to the ECU or cant find it now? Though it seems I can still send commands to the ECU individually? Unless I am still confused as to what units I am talking too.

Even before I "tinkered", the bin file I copied from the unit would save as a 134kb file? (Approx). So the Flash Tool would see it as an invalid file and even then wouldnt allow me to send it to the unit?

A thought, what issues would occur if the car key somehow isnt quite working right? Does it actually matter on the Vx at all? Is it just a resistive check on the key ring for the car to give the ok to start and run?

Regards.

[pman92]

From the issues you have explained your problem has nothing to do with the key or anti theft system.

The key works something like this:
The key isn't just a resistive check, the key reader ring connects to the BCM. At ignition on, the BCM reads the code in it and decides if its right. The PCM initially cranks and starts as normal, and sends a message to ask the BCM if its ok to start. If it hasn't received an 'ok to start' response within a couple of seconds it will shut off. The PCM also have to be linked to match each other.

If there was a key problem flashtool would still have no problem communicating with the PCM, even if you inserted the wrong key

[JohnDee68]

Thanks pman92,
that would make sense of both the key not being the fault and the failure to start being the security not allowing the firing or fuel supply to happen and just cranking of engine.

VL400, I thank you for your offer to help if I send you my BIN file and PCM? Just to make sure I would send you the correct hardware, is it this unit that i send to you? (I of course I will need your address details, via pm, to know where to send it also.).

Attached is a pic of the device I believe to be the unit in question of repair? It is located behind the front passenger LH kick panel. would that be the correct device i an needing to send? Or is there another unit somewhere I am unaware of?

thanks guys.

John.

[antus]

Thats it, but note that he said the original bin without clear registers. I think thats because it'll have information from your car in it. Do send him the file PM first, so he can check that it will be suitable for him to repair with before you post.