Electrical issues spreading like a cancer, help please?

[GrahamA]

My problems began with a flickering nearside headlight but has now started spreading to other areas so any help would be greatly appreciated, I initially replaced the bulb, then the igniter, then the ballast on the headlight all to no effect. Then this evening the lights in the passenger door for the seat controls side started flickering and this was followed by the script on the dash of 'consumer electronics offline' , which had randomly come up on it's own two days previously and me fully charging the rear battery.

There is also a smell that I would describe as similar to burning plastic in the engine bay, but for the life of me I cannot find where it may be coming from and this may in fact be hot oil from a slightly weepy rocker cover gasket?

I've checked for water in the airbox and the drains either side just ahead of the front windscreen suspecting possible water ingress but all these are clear, so if anybody has experienced this and can point me in the right direction it would be greatly appreciated.

 

[mersum1es]

Measure the current draw. How much car is charging (from battery poles)?

 

[mioba]

I would be checking your fuse box(es) for signs of water ingress.

 

[GrahamA]

Measure the current draw. How much car is charging (from battery poles)

Which battery, or do you mean both?

 

[GrahamA]

I would be checking your fuse box(es) for signs of water ingress.

I looked in the fuse box under the bonnet on the drivers side near the base of the windscreen and that's as dry as bone and there's no smell of burning coming from there?

 

[GrahamA]

Sorry I should have said in the title, my car is a 2003 R230 SL350.

 

[mioba]

Check that the connectors to the headlight are all snug, the burning plastic smell could be indicative of a loose connection and some sparking, you need to do some detailed inspection and follow all wires you can see and fing the culript. seems you have a short somewhere whihc has melted through some insulation and giving you all the issues you describe..

Check also your earths are clean and well ground

 

[sausage]

Poor battery condition can play havoc with cars like the SL. Is the consumer battery the original? If so, it might be due a change.

The error linked to your consumer circuits - the consumer battery could be the first thing to check. Have you been for a LONG drive and I do not mean 20-30 miles. Doing so might give your consumer battery a good recharge.

I would start to look into what my options are with the consumer battery: Can I charge it? Can I borrow one? Do the errors match other peoples consumer battery issues? Can my local indy hook up something such as a spare one to see if that clears errors.

My Range Rover was similar, there were about 150 fuses, possibly more(some fuses are shared by up to four circuits). I removed the -VE battery connector put a multi metre between the -VE battery pole and the -VE battery connector and pulled the fuses one by one until I found the circuit that was causing my drain. Boring and tedious but easy. The problem with the RR is that there are three computers, and a body control module that all wait for shut down signals or time outs from the hundreds of circuits, and certain circuits take upto 40 minutes to shut down, and only when the last have shut down does the computer allow the car to power down and only then is it possible to check for a parasitic battery drain. However, I did this and removed 7 amps of parasitic drain which is enough to flatten the massive RR battery in a couple of days.

 

[mioba]

you can fathom poor battery simply with a multimeter, I am more concerned about the burning smell and the failing of further components.

 

[GrahamA]

Check that the connectors to the headlight are all snug, the burning plastic smell could be indicative of a loose connection and some sparking, you need to do some detailed inspection and follow all wires you can see and find the culprit. seems you have a short somewhere which has melted through some insulation and giving you all the issues you describe..

Check also your earths are clean and well ground

Myself and a friend, who's pretty good with this stuff, have looked and looked but can't see where it's coming from, sadly my local indy who are excellent and my go to place are closed for at least another week due to Covid. I phoned a local auto electricians who are usually excellent but with Mercedes they recommended my local indy so a catch 22 situation.

 

[GrahamA]

Poor battery condition can play havoc with cars like the SL. Is the consumer battery the original? If so, it might be due a change.

The error linked to your consumer circuits - the consumer battery could be the first thing to check. Have you been for a LONG drive and I do not mean 20-30 miles. Doing so might give your consumer battery a good recharge.

I would start to look into what my options are with the consumer battery: Can I charge it? Can I borrow one? Do the errors match other peoples consumer battery issues? Can my local indy hook up something such as a spare one to see if that clears errors.

My Range Rover was similar, there were about 150 fuses, possibly more(some fuses are shared by up to four circuits). I removed the -VE battery connector put a multi metre between the -VE battery pole and the -VE battery connector and pulled the fuses one by one until I found the circuit that was causing my drain. Boring and tedious but easy. The problem with the RR is that there are three computers, and a body control module that all wait for shut down signals or time outs from the hundreds of circuits, and certain circuits take up to 40 minutes to shut down, and only when the last have shut down does the computer allow the car to power down and only then is it possible to check for a parasitic battery drain. However, I did this and removed 7 amps of parasitic drain which is enough to flatten the massive RR battery in a couple of days.

I replaced the consumer battery when I bought the car just over 3 1/2 yrs ago, this is my only car so it doesn't always get long journeys but it does get regular use. Perhaps something is dragging the battery down as when the car was at my local indy, who are currently closed due to Covid, recently for it's service they said they'd had to charge the auxiliary battery as it was testing low, their report said 'Main battery state of health - 78%/charge 20%'

It looks like I could be in for a tedious morning tomorrow pulling fuses although with the accompanying burning smell it could as suggested be a short somewhere, if only I could find the darn thing!

 

[LostKiwi]

Where are you based. Maybe we can suggest another Indy.

 

[GrahamA]

Check that the connectors to the headlight are all snug, the burning plastic smell could be indicative of a loose connection and some sparking, you need to do some detailed inspection and follow all wires you can see and fing the culript. seems you have a short somewhere whihc has melted through some insulation and giving you all the issues you describe..

Check also your earths are clean and well ground

D you know of a diagram anywhere please that would show where the main earth points are to check please?

 

[GrahamA]

Where are you based. Maybe we can suggest another Indy.

Hi Alastair I'm in Ipswich, Alex Crow would be my next nearest I would guess, as the lights on the passenger door controls were also flickering I'm wondering if it's something to do with the lighting circuit on that side of the car rather than perhaps the battery. Although I have no idea why this problem would suddenly develop, perhaps it's just old age?

 

[sausage]

I don't want to send you on a wild goose chase.
The first reply suggesting checking your charge rate. So this means engine running, what is the voltage on the main battery during charge. Do be ****** careful of the battery it carries huge amounts of amps which is enough to do some serious damage to you or other components. So, the charge on your main battery when the engine is running should be about 14.x volts if your alternator is doing it's job properly. Not sure what the charging voltage should be on the consumer battery when the engine is running, but someone might be able to offer an answer, or google might. But, that would be my first thing - ensure that the car is charging both as it should be.

After that, I would likely try and find a way to try a different consumer battery, in light of the comments from your mechanic. IF I were able to determine the car is fine and it is just the battery then I might start to look at a drain. With the multimeter across the -VE side, and all fuses in, and the engine off, you will see the full extent of the drain. The purpose of pulling fuses is to try and see which circuit reduces the drain. There might be more than one.

 

[GrahamA]

So I checked the batteries with a multimeter to check the alternator output.
Straight after starting the engine the consumer battery showed 11.47 volts, which is obviously low and the 'consumer electrics offline' inscription had come up on the dash.
I checked the main battery straight afterwards and it was 12.49 volts. I returned to the consumer battery still with the engine running and it was literally within that short time now reading 13.0 volts and rising so I'm assuming the altermator is OK.
So I'm thinking that leaves me with a short somewhere, quite possible given the accompanying smell, or a defective consumer battery?

 

[GrahamA]

Maybe worthy of a mention or not but the nearside headlight works fine for several minutes when you first turn it on before flickering and going off.
If you turn the lights off for around 10 minutes it the process repeats itself, fine for a few minutes and then goes off again.
If there was an outright short somewhere I would have thought it would the headlight would not reset itself so to speak?

 

[LostKiwi]

Have you had a Star session? This sounding like a SAM or CAN issue.

Check the CAN bus connection in the drivers side door sill isn't wet or corroded.

 

[SL63 Mark]

It all comes back to proper diagnosis I am afraid. Until you can book it into Alex, I would leave it safely tucked away in the garage.

 

[sausage]

Yep, worth checking the basics but there comes a time to go to the experts.
You should note that starting the engine and stopping it without at approx a 20 mile run is a good way to dent your batteries.
Battery charge can settle after a while. Might be worth doing another read after the car has sat for an hour or so and seeing how low this reads have dropped. This would be an indicator as to how well your battery is holding charge, and therefore some level of insight into it's health.