2888395 - K21 FUEL RESERVE WARNING LIGHT NOT WORKING

With the ignition key in the ON position, the fuel reserve warning light does not come on when the tank is empty or comes on when the tank is full.
When the ignition is turned ON, the fuel reserve warning light comes on for about 4 seconds as a self-test, then goes out. If it stays on flashing, and at the same time the gauge goes to "0", this means that there is a fault in the connection (short circuit to earth or A.C.) or in the fuel gauge sender unit.
Results of the tests
1CHECK INSTRUMENTAll OKProblems metOperation
Check the instrument is working properly, particularly the fuel level signal check device see DESCRIPTION AND OPERATION: 5560 INSTRUMENT PANELContinue to Step 2Instrument not workingChange the instrument Op.   5560B10 
2CHECKING CORRECT OPERATIONAll OKProblems metOperation
Check that the fault is no longer presentEnd of diagnosisFault persistsSearch for the fault starting from another symptom'