I see. Thanks for the information.
A computer initiated regen will override any switch position issue. This will only happen when ET and a forced regen.
If the brake clutch and accelerator are not causing the system not to regen. I would next look at the pending checks before the regen. The pending checks are:
Secondary air gas mass flow must be within 150-220 ib/hr
Fuel pressure control command must be between 50-80%
CGi mass air flow must be below 500.
If any of these are not met, the system will not initiate a regen with the manual switch. If these are all within specs, there is only one other thing that can cause a manual regen not to start. That is the ECM is detecting too much load on the engine. If the ECM thinks its under load and a parked regen is wanted, it will just not start a regen. IT detects load by fuel pulse commands to the injectors. If the pulse command is too high, it will not do a parked regen. The only thing I have seen take care of this problem is to relieve a known load on the engine. PTO, Air compressor, fan, etc. I like to verify this by removing the fan belt and removing the load from the engine. if it does a regen. Youll know its detecting too much load.
Now, this does not mean these items are necessarily bad. It normally means the injectors are worn and the ECM needs to extend the pulse command to hold the engine speed. The ECM thinks the engine is under load a will not start a regen. Ling story short. Worn injectors can cause your problem. I am sorry. I wish I had better news.
Please reply back if you need more help or have more questions. I am happy assist.