Bulb failure indicator light, function - GF54.15-P-1520A
MODEL 202 up to 31.5.97
The lamp monitoring unit (N7) in the fuse and relay box (F1) monitors the function of the bulbs in the following circuits of the exterior lights:
- Low beam
- Standing lamps
- Tail lamps
- Stop lamp
In the case of the low beam, standing lamps and tail lamps, the lamp monitoring unit (N7) also monitors the function of the fuses.
The status of the bulbs and fuses is sensed by means of constant current measurement. If all the bulbs are in order, there is a positive signal (12 V) at the lamp monitoring unit (N7). If a bulb or a fuse has failed, there is a negative signal.
The failure of a bulb or fuse in the circuit of the low beam, standing lamps or tail lamps is indicated by the bulb failure warning lamp (A1e14) in the instrument cluster (A1), but only when the exterior lights are on.
The fail of a bulb in the stop lamp circuit is indicated by the bulb failure warning lamp (A1e14):
- With "Terminal 15 ON", when the service brake is applied.
- While driving, only for as long as the engine is running.
As a self-test, the bulb failure warning lamp (A1e14) lights up for approx. 30 s when the ignition or glow start switch is in position 2 "Terminal 15 ON"; it goes out immediately if the engine is running. Because a bulb failure is indicated after individual measurement, an incorrectly installed bulb with an insufficient power rating may also be indicated as a failure. A bulb with an excessively high power rating is not indicated.
When retrofitting additional lights, such as additional headlamps, auxiliary stop lamps, trailer hitch etc., care must be taken to ensure that these are connected to the fuse upstream of the lamp monitoring unit (N7). Other types of connection may lead to false indications of the bulb failure warning lamp (A1e14) and to damage to the lamp monitoring unit (N7).
| Removing and installing fuse and relay box | Model 202.01/02/12 up to 30.11.94 | AR54.15-P-1255EA | |
| Model 202.01/02/12 as of 1.12.94 up to 31.8.96 | AR54.15-P-1255ED | ||
| Models 202.01/02/12 as of 1.9.96 up to 31.5.97, 202.07/08/18 up to 31.5.97 | AR54.15-P-1255EE |