Pagoda SL Group

W113 Pagoda SL Group => Electrical and Instruments => Topic started by: Ross Parker on June 17, 2015, 14:00:17

Title: Not Charging Light is on, and "it's not charging"
Post by: Ross Parker on June 17, 2015, 14:00:17

Hi everyone....I could use some help. I've checked the previous threads and can't find what I'm looking for.
Bottom line is: where is the voltage regulator on my '68 280SL, US model, auto trans?
Here's the background...
-everything was fine, until the battery went dead because there was a big dead short.
-fixed the short, replaced the battery.
-in the process of replacing the battery, I inadvertently shorted the hot and ground on the little terminal block that sits on the front of the oil pan.
-car starts fine, but now "battery not charging" light is hard on...and it's true, it's not charging.
-when engine is running, and I remove the grounding wire off the battery, engine instantly stops.
-all fuses in the firewall panel are fine.
-took alternator off the car, had it bench tested. It is working fine.
-I believe alternator is original. The 'alternator bench test' guy said "you've got an external voltage regulator on that car. Check it"
So, I can't find another 'in-line' fuse in the charging circuit, and I can't identify the voltage regulator to check it out...maybe I fried it with that momentary "shorted at the little terminal block".
Any help in pointing me would be appreciated......Ross

Title: Re: Not Charging Light is on, and "it's not charging"
Post by: Jonny B on June 17, 2015, 14:24:47

Voltage regulator is mounted on the inner passenger side of the engine bay. It is a small metal box and should have a band of yellow tape around it. I am traveling this week and am not able to post a photo.

I replaced the alternator in my 250 SL a couple of years ago due to a short, and when we purchased the new alternator, we also got the recommended solid state replacement regulator.

Title: Re: Not Charging Light is on, and "it's not charging"
Post by: ja17 on June 17, 2015, 14:31:38

The voltage regulator is the silver box on the left side of the engine compartment. It is near the left shock tower. It has a three-pronged plug hooked to the bottom of it.

Title: Re: Not Charging Light is on, and "it's not charging"
Post by: Ross Parker on June 30, 2015, 12:41:26

Thanks everybody.....FIXED !!
It was the voltage regulator !!
The "alternator bench test" guy, tested the regulator (which was original) and said "it's not working properly, and, it gets hot"
I took it apart, and it seemed ok, except for a slight build up on one side of the points.
I decided not to file it down, but rather to get a new voltage regulator.
NOS on E-Bay $110 usd, sourced in USA.....likely 3 weeks away.
Parts supplier near my home found a new one (not OS) in Calgary supplier's warehouse.....$70 cdn, here in 3 days !
Installed it (same style of wiring connection plug) and alternator.
Connected battery, and fired it up !!
No flippin idiot light !
Wahoo....just in time for the July 1 Car Show tomorrow!!
Thanks again....this is a great Forum site !! ;D

Title: Re: Not Charging Light is on, and "it's not charging"
Post by: Ross Parker on June 30, 2015, 21:42:04

....oh, in case yer interested....the $60cdn voltage regulator that solved the problem, and had the perfect line up of plug connectors and bolt holes to the fender, was from Intermotor, VR 124....Ross