Alternator Replacement...
Thread Starter
Senior Member
Joined: Apr 2020
Posts: 390
Likes: 83
From: North Dakota
2021 G550, BMW X5M, 2020 Toyota Supra LE
Alternator Replacement...
Since I bought my truck about a month ago it had a hum when driving it, I figured the alternator was on the way out, but everything tested ok.
Fast forward you today, driving to work, turned on heated seat and steering wheel and I get a red battery warning light.
Manual states that light is illuminated when: the battery is no longer charging, a broken V-belt, battery was jump started or when the battery has insufficient voltage. I popped the hood and the belt is still there. Restarted the car without heated seats and heated wheel turned on and no warning light.
99% sure the alternator needs replacement, but won’t know until I get home to test it.
Anyway, a few questions for everyone:
1). Is there a vendor on this site with competitive pricing? Looks like Rock Auto has the Bosch OEM with lifetime warranty for 265.79.
2). Is there anything else I should replace, “while I am in there.”
3). Any tips/tricks on the swap out?
Thanks in advance.
Fast forward you today, driving to work, turned on heated seat and steering wheel and I get a red battery warning light.
Manual states that light is illuminated when: the battery is no longer charging, a broken V-belt, battery was jump started or when the battery has insufficient voltage. I popped the hood and the belt is still there. Restarted the car without heated seats and heated wheel turned on and no warning light.
99% sure the alternator needs replacement, but won’t know until I get home to test it.
Anyway, a few questions for everyone:
1). Is there a vendor on this site with competitive pricing? Looks like Rock Auto has the Bosch OEM with lifetime warranty for 265.79.
2). Is there anything else I should replace, “while I am in there.”
3). Any tips/tricks on the swap out?
Thanks in advance.
MBWorld Fanatic!
Joined: Nov 2002
Posts: 1,028
Likes: 133
From: Massachusetts
2018 GLE350, 2014 G550, 2000 SL500, 1980 TR8, 1995 E320 Cabriolet
I'm 99% sure you only need to replace the voltage regulator for about 40 bucks. The main body of the alternator (windings, diodes, and bearings) rarely fail, but the brushes on the VR do wear out. Use only a new Bosch regulator. I can't remember for sure on a G, but it may be possible to replace the VR with the alternator on the car.
Thread Starter
Senior Member
Joined: Apr 2020
Posts: 390
Likes: 83
From: North Dakota
2021 G550, BMW X5M, 2020 Toyota Supra LE
I'm 99% sure you only need to replace the voltage regulator for about 40 bucks. The main body of the alternator (windings, diodes, and bearings) rarely fail, but the brushes on the VR do wear out. Use only a new Bosch regulator. I can't remember for sure on a G, but it may be possible to replace the VR with the alternator on the car.
Looks like on the G500 the alternator needs to come out.
Thanks again!
Thread Starter
Senior Member
Joined: Apr 2020
Posts: 390
Likes: 83
From: North Dakota
2021 G550, BMW X5M, 2020 Toyota Supra LE
Man that alternator is a pain. Took the belt off, got the 2 E-14 bolts out, but was having a hell of a time wiggling the alternator out of the brackets. My hope was that I could just roll the alternator (front down) and replace the voltage regulator, as it appears to fully remove the alternator, you would need to remove the cooling fan, fan shroud, maybe even a coolant hose. D’oh!
After messing with it for a while, I gave up and threw it all back together.
It is getting a lift installed on Tuesday and I wanted to make sure the car was drivable by then. Lol
