Test Alternator Diodes - AR15.40-P-9301-02CW
WARNING: This page is about a different car, the 2023 Mercedes-Benz GLC300, 2022 Mercedes-Benz GLC300, 2021 Mercedes-Benz GLC300, 2020 Mercedes-Benz GLC350e, and 2020 Mercedes-Benz GLC300. However, it is still accessible from the selected car via links, so may be relevant.
Engine 156, 271 in model 212
Engine 156, 271, 272, 274, 642, 646, 651 in model 204
Engine 271, 272, 273, 642, 651 in model 207
Engine 271, 274 in model 172
Engine 274 in model 205, 253
except code ME05 (HYBRID DRIVE 80KW VARIANT (INCLUDING PLUGIN))
Engine 274 in model 213
except code ME06 (Hybrid drive 60 kW variant (incl. plugin))
Engine 274 in model 238
Engine 276.8 in model 205, 253
Engine 276.8 in model 213, 238
Engine 642, 651 in model 218
Engine 651 in model 205, 253
Connection scheme, shown on model 172
 Courtesy of MERCEDES-BENZ USA
|
Connection scheme, shown on model 205.002
 Courtesy of MERCEDES-BENZ USA
|
- Connect Engine tester with oscilloscope (030).
- Start Engine.
- Switch on low beams.
It is not possible in this test to assess the exciter diodes.
- Assess diode harmonic content at 3000 RPM (Engine speed).
Example: Diode harmonics OK (voltage spikes possible, but not significant).
 Courtesy of MERCEDES-BENZ USA
|
Example: harmonics when a positive diode is defective.
 Courtesy of MERCEDES-BENZ USA
|
Example: harmonics, when a negative diode is defective.
 Courtesy of MERCEDES-BENZ USA
|
Example: zero line, if the alternator (G2) fuse is defective.
 Courtesy of MERCEDES-BENZ USA
|