staggs

Hello,
joined as I am at a loss with my current ML320 2002
developed intermittent starting issue ( not turning over first time)
eventually it now attempts to turn over, immediately does and then I have a pretty depleted battery. And the start error message on the dash
so the car has not gone anywhere
prior to this and maybe connected, if the vehicle isn’t driven everyday the battery will deplete
( have had 2 new batteries in the last 2 years)

initially replaced the started motor- nope
then the immobiliser module (ring and matchbox sized thing) -nope
not sure where to look next, fuses all ok
was going to check earths, as there seems to be a drain somewhere, but I’m not a mechanic, so trying to work through it.
any ideas on this please?
thanks in advance if anyone can offer help

Bezalel

Hi, I have had much the same problem, for a decade! My low cost solution is to keep the car trickle charged with a 20W 12V solar panel on the dash, plugged into the 12V power outlet in the footwell. This is active when the car is off, and so feeds in juice to the battery all the time. A 20W 12V PV panel is the largest that doesn't need a solar controller. For me, I think the mystery electrical short is either in the tow hitch electrics or the parking sensors, but being a) lazy and b) broke, a Ł40 solution seemed a good idea at the time! However, the PV panel will also charge up the battery from dead flat given enough time.

The long term idea was to put a 250W PV panel on the roof and run a big battery and inverter etc., for camping.

staggs

Hi, and thanks for the suggestion, I don’t have sensors or tow pack, removed the latter years ago because I wasn’t going to use it.. pretty sure it’s a bad earth or frazzled wire somewhere, but just can’t find it,
I have been able to jump it off with my noco but I never had the start error message until recently..
and neither the noco or a fully charged battery will do the trick now…
going to have to consign her to the barn I think!

streborx

How old is your battery? Just because a battery can start a car when fully charged doesn't mean it's capable of holding its specified amp hour capacity, and not self-discharging. Have it checked by a dealer or auto store.

Jerry Easley

Don't 'consign these W163's to the barn'!

First: I recently had an intermittent 'battery drain' problem. Found it to be the ignition switch. When I removed the key it would sometimes not disconnect the 'key present' circuit. Fixed it with a judicious dose of lock lube (not graphite!). It was a 2 year old brand-new lock tumbler. The original was well worn at 190,000 miles. (a VIN matched ignition tumbler and emergency key (Mickey Mouse) were available from classicparts.mbusa.com)

Second: Go to this tutorial attached. A fellow forum member I was helping with another problem used it to find his 'battery drain problem' and reported it to be 'excellent'.
"L35 in Colorado" has several W163 videos. These are well structured, professional quality narration, with still-shot annotations, and 'clear as a bell' we would say on this side of the pond. No click-bait antics nor distracting background sounds.
One of the best I have seen from L35 is on removing the dash to fix broken "climate-control" actuator arms. Major Dundee also has on this forum a good tutorial on how to remove only the upper dash to do the same repair.

Third: Here in USA, O'Reilley's Auto Parts carries in their loaner tool inventory an "Amp Hound" for finding parasitic drain. "Free" to borrow, or can be purchased. I used it once, it makes diagnosis much easier and more certain.
Not sure if your chain-store parts houses have this program, but it can be reasonably purchased as well. https://www.oreillyauto.com/detail/c...ter/ren1/67355
And they carry an affordable Circuit Tester. Both by EverTough

Please post back with what you find - others can use 'the rest of the story' as parasitic drain can be a frustrating puzzler.

You Tube

Jerry Easley

@Bezalel "A 20W 12V PV panel is the largest that doesn't need a solar controller."

Please explain for me, as I am setting my VW New Beetle aside (windshield facing south) for a few months, but want it to be driveable by family members if need be.

I was planning on a solar charger but was under the impression any could cause damage if not with a 'controller'.

Jerry Easley

No need to be at a loss.

Attached is a Starter Circuit with troubleshooting notes. Easy enough to do, Takes less than 1/2 an hour 'hands-in'.

Start with streborx post. A 'dead' battery just freshly topped to 12.6v may not have amp capacity to start the vehicle, especially if degraded by drain - charge - drain - charge cycles.
Get a load test on the battery (Best, and most definitive),
or 'will the W163 start if properly jumpered'? (Expedient only, not definitive).
Keys out both vehicles, connections made in order of owner manual, booster vehicle started, then given time - maybe 10 - 15 minutes @+1300rpm.


I added a 'shareable' how to article.

Good luck, post back results.

Bezalel

Buy another one then and use the old one as a parts car! : )

It might just be a microswitch faulty...

staggs

suspected electrical issues

it’s less than a year old, tried to jump with both a NOCO and a second fully charged larger battery but it almost turns over then dies, and start error on the dash

Jerry Easley

Did you remove the ‘dead’ battery and install the fully charged battery, or try to jump to the installed dead battery?

A dead cell in the “old” battery can stop current flow.

Complete the tutorial steps. That will point you to a solution either switch circuit, or hi-amp starting circuit.

Let us know what you find.

Diagnosis is your friend.