Mercedes-Benz Tech Tip: Insufficient Alternator/Generator Output

Mercedes-Benz Tech Tip: Insufficient Alternator/Generator Output

On select Mercedes-Benz model vehicles, if you encounter insufficient alternator/generator (G2) output, the voltage regulator, integral to G2 output, may be malfunctioning. The voltage regulator may be replaced as a separate part and the procedure in this Tech Tip should be followed.

Affected vehicles: All model 203, 209, 211, 215, 220 and 230 with M112/113 engine, all model years

On the above model vehicles, if you encounter insufficient alternator/generator (G2) output, the voltage regulator, integral to G2 output, may be malfunctioning. The voltage regulator may be replaced as a separate part and the procedure below should be followed.

1. Check regulation voltage of the generator (G2) as per WIS instructions:

– Model 203/209: AR15.40-P-5010P
– Model 211: AR15.40-P-5010T
– Model 215/220: AR15.40-P-5010I
– Model 230: AR15.40-P-5010R.

2. If the generator fails the above test procedure, then remove the unit from the vehicle for repair on a workbench. Refer to WIS Group 15.40 for the correct instructions, depending on the model and body variant.

Fig. 1

3. Remove the plastic cover from the rear of the generator, by first removing the two nuts from the studs (Fig. 1, 1) and the one Philips head screw (Fig. 1, 2). Note which nut is removed from either stud.

4. Remove the voltage regulator (Fig. 2, 1) from the generator, by removing the three Philips head screws (Fig. 2, 2 and 3).

Fig. 2

5. Check the following prerequisites to ensure that only the regulator needs to be exchanged. If any of the following items fail, then the entire generator needs to be replaced and you may proceed to step 8.

a. There are no scorch marks or damage on the slip ring of the generator rotor (Fig. 3, 1).

Fig. 3

b. The carbon brush length of the defective regulator is at least 5 mm (Fig. 4, 1).

c. The wear on the two brushes of the defective regulator is even (maximum 1 mm difference).

6. Install the new voltage regulator and tighten the Philips head screws to:

Fig. 4

a. Fig. 2, 2 = 2.0-2.4 Nm.
b. Fig. 2, 3 = 1.0-1.4 Nm.

7. Install the plastic cover on the back of the generator and tighten the Philips head screw (Fig. 1, 2) to 2.2-2.6 Nm and the two nuts (Fig. 1, 1) as follows:

a. Long stud to 29.0-32.0 Nm.
b. Short stud to 11.0-13.0 Nm.

8. Reinstall the repaired generator or the new generator in reverse order and verify proper operation as described in step 1.

Note: Due to the several versions of alternator/generators used in production on all the above models, please refer to EPC for the correct voltage regulator part number application. The correct part numbers may be found in group 15 and/or 54 in EPC.

Courtesy of Identifix.

You May Also Like

TEXA Releases IDC5 CAR 76.5.0 Update

IDC5 CAR 76.5.0 is characterized by over 2600 new possible selections for the major makes on the market worldwide.

TEXA has released a major update IDC5 CAR 76.5.0 which enhances Car, Supercar and Light Commercial IDC5 diagnostic features & coverage. This latest software update enables more efficient troubleshooting, enhances existing special functions and topology module mapping features, while increasing technical information accessibility that is essential for accurately completing complex workshop operations. IDC5 CAR 76.5.0 includes the update of 37 makes, including electric and hybrid vehicles, while increasing the coverage of ADAS calibration, enhancing the visual live data "DASHBOARD" screens and other interactive technical information features like wiring diagrams, maintenance guides and component location diagrams.

TechShop, ShopOwner Offer $50 For Good Guesses

Guess the Tool for a chance at cold hard cash!

TS Toolbox Guide February 2024

Here’s a look at some of the core feature and modern frills to consider when it’s time to move into a new office.

toolbox guide illustartion
Embracing Cutting-Edge Solutions the Industry has to Offer

Embracing cutting-edge solutions is strategic and imperative for technicians navigating the constantly changing landscape of automotive maintenance and repair.

Nadine Battah
TPMS: Are Retrofits in Your Future?

Installing a retrofit kit can be performed with the tools and equipment you already own and use on a daily basis.

Tire tread

Other Posts

New Snap-on Limited Edition Speed Demon Roll Cab

Features include next-level organization, durability, security, mobility and exclusive Speed Demon emblem.

ISN Expands Freedom Program for Mobile Tool Dealers

ISN’s Freedom Program is designed to provide experienced, successful mobile tool dealers with support to become an independent mobile dealer and expand their growth.

Snap-on Continues to Offer Free Weekly Product Training Sessions

The online training and question and answer sessions are free of charge.

Repairify Announces Executive Leadership Changes

The company has named Craig Edmonds as president of asTech among other executive appointments.