|  |  | Results of the tests | 
| 1 | CONTROLS CHECK | All OK | Problems met | Operation | 
|---|
|  | Check
that the + / - mode buttons on the Computer left controls panel
are working properly:  See   E2530  INSTRUMENT LIGHTING | Continue to Step 2 | Switches faulty | Replace the left control panel  Op.   5560B56   Continue to Step  2 | 
| 2 | CHECKING ELECTRICAL CIRCUIT | All OK | Problems met | Operation | 
|---|
|  | Verify: Connections between left control panel and NQS;Connections between controls panel and junction unit
 | Continue to Step 3 | Connections / supplies
not correct | Restore correct connections / supplies:  See   E2530  INSTRUMENT LIGHTING | 
| 3 | CHECKING  WITH DIAGNOSTIC EQUIPMENT | All OK | Problems met | Operation | 
|---|
|  | Connect
an Examiner to the diagnostic socketCheck the operation of the panel light through the active diagnosis
of the instrument panel. | Continue to Step 4 | Light does not change,
instrument panel defective | Replace instrument panel  Op.   5560B11 | 
| 4 | CHECK ON CORRECT OPERATION | All OK | Problems met | Operation | 
|---|
|  | Check
that the fault is no longer present |  | Fault persists | Search for the fault starting from another symptom' |