we have two linkbelt 290 excavators and both have the issue where it throws an alarm says it has an alternator fault but when you check the cables coming off the alternator it is charging fine i believe they both are putting out 27 to 28 volts. just wondering if anyone else has had this issue
welcome to the site! i have a case 9040b which is also a sumitomo, i thought i had an alternator issue for about 2 years because it sounded an alarm that said check battery level. come to find out, guys on here pointed to the issue, it was a sensor that detected electrolyte levels in the batteries. hook that dude up and no more fault.
How may hours on the 290s.
The wiring on a case 290 should be similar. Check the alternator diode, case part#231959A1. You will have to follow the alternator harness, and there should be a connector for the diode. Its probably corroded or failed.