Unable to change RPM via S86 in Liebherr wheel excavator A904C 1004-6xxxxx

[nashink]

Hello,

I am having a very peculiar problem.

So when the machine starts fresh in the morning the excavator works just fine. However, once its turned off and on again the problem starts.

The problem being we are unable to change the RPM via keyboard. The S86 (mode selector) blinks ( as per manual it means that the engine rpm is not responding to input). And the engine runs below low idle rpm with sort of in load. However we can increase the engine rpm via acclerator pedal

So far we have checked the following variables that is checking the continuity to flywheel sensor (B12) from U16, Checking and swapping the control module U16, Reconnecting the each connector on A1001 & A1010 circuit. Changed the injectors and fuel pumps on the engine, however the problem still persists

Any suggestions regarding solving this problem would be extremely helpful as we are trying to fix this problem for over 7 days.

 

[KisstDiagnostics]

It could be something simple, or it could be the keyboard isn’t sending out the signals to the allocated pins on the circuit, if everything checks out then maybe there is a software update for the can bus communication between the on board ECUs.

 

[nashink]

It could be something simple, or it could be the keyboard isn’t sending out the signals to the allocated pins on the circuit, if everything checks out then maybe there is a software update for the can bus communication between the on board ECUs.

Hello,

I thought that the keyboard wasn’t sending signal, however once the machine is let to cool down for some hours or started after overnight, it works just fine.