Hi everyone, I have mini excavator Volvo ECR28 2009 year. It was running fine, but the problem start to come more often than before. The glow plug lights is not showing on the dash (i-ecu) , the starter turns but it doesn’t start the engine, because the solenoid on the pump is not pulled. It doesn’t start , if I do not bypass the solenoid valve on the pump. I am connecting the pull coil on the pump solenoid to the positive (live) wire on the starter when engaging after 2nd key position, and it starts right on. But the hydraulics the offset boom, the hammer (3rd function) and the auto idle don’t work. It is like the ecu is bypassed. I have checked every single fuse and relay in the fuse box, I checked the wires connections as far I can see and all seems fine to me, but I do not know what to look for. There is live on the glow plugs when I turn the key on second position. I have checked the key switch also and it sends signal. I took out the V-ECU to look at it, but is seems fine. I have all the wiring diagrams from Volvo Prosis, but not quite sure what to look for. In twenty starts sometimes the yellow glow plugs appear on the dashboard and everything works fine , the offset hydraulic, the third function everything and it could work fine for the next 3-5 starts and then just the button for the offset become inactive and that’s it, if you turn off the engine you won’t be able to start it again, if you do not bypass the solenoid on the pump. If someone can give me a suggestion what to check for, I would be very much grateful.
Found the problem ! Checked all the wires again and the only unit the give instructions to the glow plug, the pull coil on the pump and the hydraulics is the V-ECU. I opened the V-ECU and the chip is burned. The chip is 4 way switch (pull start coil, glow plugs, prop hydraulic, offset boom ). I have to change it , and hopefully it will work again.