MT855C Throttle and Engine Info Issues CHRYSLER 300M Saloon (LR) (07.1998 - 09.2004)

Hi everyone,

My father-in-law owns an MT855C, and I’ve been trying to troubleshoot some issues with it. Here’s the situation:

The engine ECU was recently replaced, and I used Cat ET software to run diagnostics. However, during a bench test, the software couldn’t establish a connection. A new control unit had been flashed on the test bench, then installed by the customer. A technician was sent out afterward to adjust the injector codes and engine controls.

After checking the settings, the throttle wasn’t working. The technician left it overnight, but now the machine has no throttle control. The display, dash, and armrest provide no engine information except RPM. While the engine runs, shifts, and the hydraulics work, the RPM is limited to 1000.

Are there any MT800C experts here who can share some tips or guidance? I’d greatly appreciate your input!