I-shift trouble

Hello, i have problem with FM12 420 D12D I-shift VT-2412B transmission, the gearbox will turn to neutral automatically sometimes but the gear selector in Drive mode when driving at flat or pulling up hill loading around 40tonne eventually with empty load, just slow down, stop the vehicle, shut off the engine and start again within few second, becomes normal and keep on going until it happen again.
This happening few week ago and getting serious cause ( restart) 8 times on yesterday around 150km journey on highway without fault codes in transmission ECU, gear selector ECU. put the truck in volvo dealer and get the quote for replace Transmission ECU, Gear changing fork unit major overhaul, sensor replace occur spend lot of money, try to put another working condition part from other truck same result, i already replace front wheel L/R ABS sensor, pulse ring, check the wheel speed sensor,ABS module with Vcads and no fault generate in Brake ECU.

any issue can cause this happen ???
please help..

thanks.

 

The driver show me today....
- when the gear change to neautral but the selector in drive mode at speed 80-100km/h,press the brake try to slow down the truck and the engine turn off automatically while the vehicle is fully stop. the engine can be start again just after few second.

- Pablo
Everything just like normal, active fault codes with climate unit, rear brake lamp, engine air filter sensor faulty, the brake lining sensor faulty, all the fault codes dont related with transmission or gear selector ECU.

anyhow, will try to get more infomation and diagnos again on tomorrow. battery cable check and also open the gearbox and check with splitter, replace wiring from gear selector ECU to dash socket, cause the air suspension seat might be issue for wiring open circuit, replace wiring from cabin socket to transmission ECU.

what do you think about major part like Transmission ECU / Gear selector ECU / clutch pump / Vehicle ECU ???

thanks for advice.

 

try to replace a new fuel feed pump cause the fuel pressure 150kpa only at idling but same, in low fuel pressure will effect the ECU free the gear and shut down the engine?

 

Another FM12 420 i-shift was fault with the same issue, transmission change to N while driving and the fuel feed pressure only 180kpa at idling....

 

lot of people mention that volvo cabovers 90 % is wiring issue...is true.
hello Pablo, Do you have skype ?? can I add you?

 

just replace engine crank case pressure sensor and everything ok.