The following table provides an overview of the alternator check procedure.
Battery Check
| Electrolyte level at least 5 mm above the | no | Fill with distilled water up to marking or | |
|---|
| plate or separator | | 5 mm above the plate. | |
| OK? | | | |
| | yes | | | |
| Check electrolyte density if possible | | Charge battery | |
| Minimum thickness 1.24 g/cm 3 | no | Measure control voltage | |
| OK? | | Replace defective battery | |
| | yes | | | |
| | | Charge battery | |
| Test battery with tester KM-J-42000 | no | Measure control voltage | |
| | | Replace defective battery | |
| Battery OK? | | | |
Alternator Check
| Is battery connected to vehicle electronics? Ground connection battery/engine/body has good connection and is free from corrosion/transfer resistance? All alternator-related wiring harness plugs are properly seated and free from corrosion/transfer resistance. V-belt tension OK | no | Connect battery Clean/replace ground connection battery/engine/body. Clean/replace wiring harness plugs Ensure V-belt tension complies with auto manufacturer data | |
|---|
| OK? | | | |
| | yes | | | |
| Measure control voltage: | | | |
| Start cold engine (no consumers) Engine speed 2000 rpm Measure control voltage at alternator B+ connection and alternator housing (not at battery terminals). Control voltage: 13.7 - 14.8 V | no | Replace regulator/alternator | |
| OK? | | | |
| | yes | | | |
| Output check: | | | |
| Position clamp-on ammeter as close to alternator B+ connection as possible Measure voltage at B+ and alternator housing Start engine Engine speed approx. 2000 rpm Switch on all consumers in vehicle During this time, control voltage must not drop below the test values. | no | Replace alternator | |
| OK? | | | |
| | yes | | | |
| Check alternator with oscilloscope | | | |
| Oscilloscope image when alternator OK | | | |
| OK? | no | Replace alternator | |
| | yes | | | |
| Alternator OK | | | |
