Mercedes - Voltage Regulator DIY Change, Fail Symptoms, Testing - R129, W124, W140, W202 and Others

In this video I show how I replaced my Bosch voltage regulator, describe common faulty symptoms, what it does and a simple performance test. The regulator is attached to the alternator.

The main symptoms of a bad voltage regulator are a no start condition, loss of car power and poor battery performance. These symptoms are often confused with a failed alternator, which is very expensive to replace and difficult to install. Most of the time this cheap $20 voltage regulator is to blame. It is considered a regular maintenance item and is meant to last 100,000 miles (160,000 km), however earlier replacement is recommended.

I didn't know it when I began the video, but I learned that my voltage regulator was soon going to fail. Luckily I changed it because the old part would likely have left me stranded!

The video and part applies and is helpful to many Mercedes-Benz including: R129 SL (300 SL, 320 SL, 500 SL, SL 600) and W124, W140, W202, W210 including models 300E, 500E, E320, S500 and C220.

Mercedes Part number: 002 154 9206
Bosch Part number: 1 987 237 075
Tools: screwdrivers, socket set

Car shown: 1992 Mercedes-Benz 300SL with engine M104.980

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Disclaimer - The content of this video is available for informational and educational purposes only. It is not intended to be a substitute for professional advice. I do my best to provide accurate and complete information, however, I assume no liability for any property or personal damage that may arise from any of the information contained in this video. Due to factors beyond the control of Handy Val, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Handy Val always recommends safe practices.