Hello everyone
I would like to ask you if the idea I have in mind is viable or not.

On a 1999 Volvo c70 T5 with Bosch me7.0 ECU I want to be able to read and write without having to take the ECU out of the car and in this car to be able to do this you have to pin-out and activate boot mode. I want to make a switch on the ECU itself so that from the outside it can activate the boot mode in a simple way (pin24 to ground) and thus be able to read and write with ktag from the car's obd. I would make a male obd connector mated to the ktag connections and connect it to the female obd of the car. I indicate ktag because Kess is not able to read this ECU.

The process would be as follows:
1º With key contact in position 0, active boot mode switch on ECU.
2nd key contact in position II.
3º I wait 10 seconds and desactivate the ECU switch.
4th at the moment with the key ignition open II and the ECU in boot mode. Could I read and write from OBD? Any problem with the positives, with grounds, immo,…? What do you think?

Thank you.
PS: I want to make it easier for me to read and write. The ecu of my car does not come out so easily.

Ok thanks AEF for the reply. But what I mainly have doubts about is whether the ECU being in boot mode and with the key switch in position II and ready to read and write can interfere with the immobilizer, generate a permanent failure (DTS) communication error with ECU, or affect the correct subsequent operation of the ECU.

I really don't know if doing the pin-out and booting with the ECU connected to the car or on the test bench have identical effects. We must bear in mind that the entire ECU would be powered in all its pins, while in the bench we only select the ones that interest us. I'm afraid that the ECU will be blocked by doing it this way.

Thank you AEF.

When I started playing with flashing ECUs, it happened that I messed them up. I was irritated by the constant opening of this metal armor, so one day I took out two wires soldered inside to the board - outside to the cheeky big switch. The car has been driving like this for 3 years - no problems.