SL/R230: Power Control Module Experiences?
Thread Starter
Senior Member
Joined: Mar 2021
Posts: 285
Likes: 23
From: Rocky Mountains, Colorado
Just sold my '11 Porsche TurboS cab for an '03 SL55!
Power Control Module Experiences?
Still sorting through various issues on my recently acquired '03 SL. I've been fooling with the 'Consumers Offline Message' for awhile and am close to buying a new Vehicle Power Control Module (eeek $600+). But am trying to gain confidence before making a bad decision. This module is variously call the Battery Control Module and Power Control Module etc. and is located in the trunk near the back of the right wheel well. I see there are one or more p/n upgrades and no used parts out there so it seems to be a chronic failure point??
My STAR DAS gives me code B1832 "faulty starter battery". Both batteries are new, the Starter Battery is MB OE, and the Systems battery is a premium Gel from Napa. They both have near full charge as judged by putting my smart trickle charger (normally on the systems battery) on either; it quickly turns OFF indicating full voltage of 13.9-14.1V or so. I also had the Starter Battery checked at the local tire shop (not a full load test like I've seen before) his hand held tool indicated 773 CCA and no bad cells.
Other symptoms: It will barely (sometimes not at all) recover the consumers after a 10 mile drive, or two 10 mile legs. Recently it wouldn't unlock the doors (luckily the window was down), sometimes the trunk won't open with the key fob, and lately after clearing the battery fault code, I started have trouble starting it - I'd get a red dash message "release brake pressure and the start" or something similar. Fiddling around seems to overcome the problem......but its pretty erratic.
Also after such an event, and 10+/- miles, I checked STAR again, no fault listed for this module (possibly not soon enough to re record it as I'd cleard it 20 mi before and 4 ignition cycles) but with the ignition on, engine off, STAR showed 8.9V!!!
Alternator seems ok as with engine on, I'm getting 14+/- volts.
Any ideas? Help appreciated.
MK19
My STAR DAS gives me code B1832 "faulty starter battery". Both batteries are new, the Starter Battery is MB OE, and the Systems battery is a premium Gel from Napa. They both have near full charge as judged by putting my smart trickle charger (normally on the systems battery) on either; it quickly turns OFF indicating full voltage of 13.9-14.1V or so. I also had the Starter Battery checked at the local tire shop (not a full load test like I've seen before) his hand held tool indicated 773 CCA and no bad cells.
Other symptoms: It will barely (sometimes not at all) recover the consumers after a 10 mile drive, or two 10 mile legs. Recently it wouldn't unlock the doors (luckily the window was down), sometimes the trunk won't open with the key fob, and lately after clearing the battery fault code, I started have trouble starting it - I'd get a red dash message "release brake pressure and the start" or something similar. Fiddling around seems to overcome the problem......but its pretty erratic.
Also after such an event, and 10+/- miles, I checked STAR again, no fault listed for this module (possibly not soon enough to re record it as I'd cleard it 20 mi before and 4 ignition cycles) but with the ignition on, engine off, STAR showed 8.9V!!!
Alternator seems ok as with engine on, I'm getting 14+/- volts.
Any ideas? Help appreciated.
MK19
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Joined: Aug 2020
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From: Gretna, NE
'03 SL55 Black, '03 SL500's Aegean, Mars Red, Tazanite, Alabaster, '11 S550 Flint Gray
Have you actually put a voltmeter on the systems battery? A smart charger will generally not charge a battery below a certain voltage. It might be kicking off from low voltage instead of a fully charged battery.
Member
Joined: Oct 2018
Posts: 86
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SL500 R230
These cars need an AGM consumer battery. A gel battery is not the same thing. Some owners get away with using non AGM but on a car with those problems then I would change the battery for an AGM before anything else.
Thread Starter
Senior Member
Joined: Mar 2021
Posts: 285
Likes: 23
From: Rocky Mountains, Colorado
Just sold my '11 Porsche TurboS cab for an '03 SL55!
Thx Keith,
Yes, it's fresh AGM from Napa. 760 CCA. But I am going now to have it laod tested as it seems like it could be my issue. My smart charger can't seem to get it to full charge.
More to follow.
MK
Yes, it's fresh AGM from Napa. 760 CCA. But I am going now to have it laod tested as it seems like it could be my issue. My smart charger can't seem to get it to full charge.
More to follow.
MK
Thread Starter
Senior Member
Joined: Mar 2021
Posts: 285
Likes: 23
From: Rocky Mountains, Colorado
Just sold my '11 Porsche TurboS cab for an '03 SL55!
Solved it!! Finally. Bad rear battery was the cause so the BCM was doing it's job. It baffled me because the batteries were new. But in the end I noticed that the rear battery voltage would fall like a rock after the engine was turned off. The AGM battery got very hot on the trickle charged and the sides bulged out just a bit...........not sure what that means but I hope my smart trickle charger isn't the cause.
Super Member
Joined: Aug 2017
Posts: 520
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From: Scottsdale AZ
2015 SL550 & 2012 S550 4matic
This is not the first “bad battery “ purchased off the shelf at chain part stores. I’m not sure why people avoid Oem batteries. I replaced both starter and consumer batteries this spring. Local dealer was pennies more but had both batteries in stock saved me a trip. Mb Parts guys said Interstate made them for MB in USA.
MBWorld Fanatic!
Joined: Mar 2018
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From: Netherlands
2005 R 230 SL350 (M112 3.7). Sold the 1966 W113 230SL recently
Mike was spot on again. Btw I bought my SL with a non AGM systems MB battery installed and the car isn’t fuzzy about it. Roof works without engine running etc. But I’ll stay alert.
