R230 bizarre electrical gremlins

[oilydave]

Hi everyone

I've been scratching my head about this one:

(1) Left-hand xenon headlamp cycles on/off rhythmically like an indicator flashing when I rev more than about 1000rpm When the car is standing idling or moving very slowly the headlamp is fine. Rev it (moving or standing still) and it flashes until it faults out, sometimes giving an error message on the instruments. I have changed (a) entire headlamp, (b) igniter, (c) bulbs. No effect.

I have never heard of this before.

(2) When standing idle for a day or two I get the message (picture of battery) "electrical consumers switched off". Usual shutdown of high power accessories. I have changed the rear battery. When I go for a drive the message stays on and the electrical consumers stay off - in other words it doesn't reset itself. The only way to remove the problem is to charge the rear battery.

Might the two be related? Car is 2003 SL500

I suspect the battery stabilisation / charge split unit, but could be completely wrong.

Does anyone have any ideas? I am baffled.

cheers

Dave

 

[Craiglxviii]

You have the right car for electrical gremlins...

Faulty earth, or lighting ECU as a starter for ten.

 

[oilydave]

You have the right car for electrical gremlins...

Faulty earth, or lighting ECU as a starter for ten.

Thanks - "lighting ecu" - you mean the xenon control unit under the headlamp? I've replaced that. Earth is definitely worth investigating.

 

[television]

The starter battery can for yours for years, mine is still good from new, just replaced the main battery 4 years ago.

 

[oilydave]

The starter battery can for yours for years, mine is still good from new, just replaced the main battery 4 years ago.

I think the previous owner had let the rear battery go so dead that it was unrecoverable, so I got a new one. Local garage tested it overnight and say it's good. When I charge it, it takes a good 25 amps but only for an hour or so then seems full, so I'm not entirely convinced that it's a battery issue

Starter (front) battery seems fine

 

[John Laidlaw]

You could be unlucky and your replacement consumer( rear) battery could be faulty- won't be the first time, we had a member on here very recently with this issue -
Otherwise a major battery drain happening which will take a while to pin down

 

[oilydave]

You could be unlucky and your replacement consumer( rear) battery could be faulty- won't be the first time, we had a member on here very recently with this issue -
Otherwise a major battery drain happening which will take a while to pin down

Thanks for the reply, john. I used a clamp-on meter and measured (from memory) about 100-130mA on the battery drain when the car was "awake" and about 20-30mA when the car was "asleep".
I did find an old tracker/bluetooth thing under the dash (wired into a spare fuse on the drivers side front fusebox) and removed this. The battery seems to stay charged for longer (previously it drained overnight) but still does so over several days.

 

[Goliath]

Have you checked the voltage on both batteries with the engine running to see if the alternator is charging the batteries?

 

[television]

The current drawn is 60ma max, other little points can come up say door ECU say 15ma and a few others should give nearer that mark. With a current why not ad them all up, a simple current check only effect under load.


I have about 7 days max, but I do charge when not in use.

 

[oilydave]

Sorry for the slow follow-up, I've been away with work.

I use a "battery brain" automatic isolator on this car and this morning (after 2 weeks) it had disconnected the rear battery. On reconnecting, I tested about 12.6v on the rear battery.

The "consumers disabled" message came up and on tickover the voltage stayed at about 12.5-12.6v. When I revved the car to about 1200rpm the voltage went up to about 13.6, but dropped back to 12.5 on tickover.

I have a Talex jump starter and I connected this (about 15v) and re-started the car. The "consumers disabled" message went off. Once the consumers (I have a Pioneer Appradio connected via the cigarette lighter circuit) and the engine running the rear battery tested at about 11.9 volts.

I had the battery tested at the garage and it tested absolutely fine.

I'll test drain currents with the car "awake" and "asleep" today

 

[oilydave]

Drain on battery about 40-50mA

 

[oilydave]

OK, more tests today.

I pulled the wiring trunk cover off on the left hand side of the engine bay and found the wiring to the headlamp. The 1.5 Yellow & black was listed as going to the left low beam from the SAM unit on the right hand side.

This tests at 12 volts with the headlamp on .... but when I rev the engine so the light flashes the voltage keeps dropping to zero and of course the headlamp goes off.

Faulty SAM unit 230 545 08 32 ??

Does anyone know if this light output is driven from a relay? There are a number of relays on the top of the fuse box/ SAM unit.

cheers

Dave

 

[oilydave]

OK, I have a dirty bodge for now:

I took 12 volts from the empty fuse 7 via a spade connector and (via a 10A inline fuse) fed that to the yel/blk cable that goes to the l/h low beam. I took a feed from the yel/blk cable on the right headlamp and fed a 12 volt relay with it, earthing the relay at the earth point near the right side fuse/sam unit. The original wiring is all in place.

I "seems" to work without fault messages. When U put the switch on BOTH headlamps come on and the left one doesn't flicker any more. Yay!

What puzzles me is that the voltage on the front lights etc (from the right side front SAM) gradually decreases in tickover.

Like the rear battery, it only seems to charge once I'm revving well above tickover - say 13-1400 rpm.

Front battery is 15 volts.

Faulty charging unit in the boot? Any ideas, anyone?

 

[Doug1234]

A fully charged battery is meant to be 12.6 volts or a touch over.
Your getting 12.5 at tickover , which should from my experience be 12.7 to 12.9 on a good alternator, and at least 14 or over when revved to about 2k.
So something is amiss with charging voltage.
Check the alternator brush pack , one of the brushes may be on the point of completely wearing out and not hardly making contact.

 

[oilydave]

A fully charged battery is meant to be 12.6 volts or a touch over.
Your getting 12.5 at tickover , which should from my experience be 12.7 to 12.9 on a good alternator, and at least 14 or over when revved to about 2k.
So something is amiss with charging voltage.
Check the alternator brush pack , one of the brushes may be on the point of completely wearing out and not hardly making contact.

Thanks. Just checked again and I get 12.1v on tickover, then 13v at 2000rpm. Probably easier to fit a new alternator then I know it's right.

 

[Submariner1]

Thanks for the reply, john. I used a clamp-on meter and measured (from memory) about 100-130mA on the battery drain when the car was "awake" and about 20-30mA when the car was "asleep".
I did find an old tracker/bluetooth thing under the dash (wired into a spare fuse on the drivers side front fusebox) and removed this. The battery seems to stay charged for longer (previously it drained overnight) but still does so over several days.

How long did you leave the car before taking the "asleep" reading ? Was it more than 4 mins.
By asleep I mean tested, shut down and locked, ( boot or bonnet latches shut .. to simulate they are closed .. leaving my bonnet clips up,can add a few mins to when it really is shutdown.)

They (Mobilo) say 40ma is fine on mine, but after say 5 mins can hover between 2 and 4 ma.

 

[brick10]

Nothing surprises me with 230s.

 

[John Laidlaw]

What, apart from it's ability to lighten your wallet considerably?

 

[triumphstag]

What, apart from it's ability to lighten your wallet considerably?

Mine just bypasses my wallet and goes directly to my bank account.

 

[SL63 Mark]

Mine just bypasses my wallet and goes directly to my bank account.

Fortunately mine does not have my bank details. Mind you it's been pretty good recently, except for the strange PSE pump pulsing.