Hi guys,

I'm having some serious issues with a GL420 CDI 4matic that I recently exported from the UK to Africa - basically when it arrived the battery was completely dead so I had to buy a new one. The trouble is I'd only just bought the car from a dealer and hadn't had a chance to drive it much when I sent it over so don't know if the issue was already there. Anyway the new battery lasted a few days then was dead again as well as the fact that the cigarette lighters all weren't working nor was the after market DVD player, the boot lock makes locking and unlocking noises whenever I open any of the other doors and the tiptronic manual shift doesn't work as well as the airmatic suspension not going up fully.

We don't have any really good MB service agents here in Zimbabwe but the guy I took it to said the rear SAM needed changing and wanted US$1,000 which MIGHT fix all the problems...the trouble is I've been reading up on the forums about this rear SAM and it sounds like it can be damaged by removing the battery and replacing which I obviously had to do. So I'm worried I'm going to pay this guy to replace the part only to have the original battery flattening issue which I also tried tracing myself thinking it was a dud fuse causing the cigarette lighter not to work but the fuse was fine so a side of the road mechanic I was with said it was an earth problem so he put in a temporary earth wire from the large grey relay(at least I think that's what it was) directly on to the main brown earth which meant I could use the 12v cigar lighters but then the battery went flat again so i was worried it was that wire and removed it but battery still goes flat AND all those other things still don't work.

I have another GL20 but 08 model that I could swap out the rear SAM for and see if that works but not sure how easy it'd be and possibly risk messing with the programming of it and then I have 2 faulty cars instead of one.

SO (thanks for bearing with me) my question is,which came first - the battery draining issue which resulted in us changing it and damaging the SAM or is the the SAM that causes the battery to drain? I've read these GL's have water penetration issues on the rear lights then leaking on to the SAM and shorting it ao that might have been the cause but would a faulty SAM drain a battery?

Unfortunately I just don't trust anyone in this part of the world to get it right - however there is one EXTORTIONATELY expensive place that has a STAR machine so would that be able to tell me everything that's wrong with it and see what the root of the problem is or will it just show the obvious things like the rear SAM and not the actual loose earth wire that I think is draining the battery which we had to bypass to get the cigarette lighter to work in the first place?

Sorry for such a lengthy drama but thought that knowing all the facts might help narrow it down... Many thanks! And incidentally if I wanted to order a new SAM online how do I know which model I'm looking for - I gather it's X164 but my chasis no is WDC1648282A136053

 

Hey Johnny, have a 2007 GL and never had the water penetration issue that you're talking about. Can't help you with the battery question, but probably next week I'll will have written a blog on how I added some LED's to the rear lights on my GL Modder's blog. There I'll show how to remove the rear lights which is very easy, maybe you can use that to patch it up a little if you are afraid of water penetrating the SAM. Did you check the fuses ? Any smells that you pick up from the compartments where the SAM is located ? Maybe if you look for something in the motor compartment that might interact with the battery... Anyhow usually you can find rear SAM units in Ebay (just checked, couldn't find a GL one though) but they shouldn't go for more than 150 GBP. Maybe better to order a second hand one before you do screw up the other one. Sorry can't be of more help...

 

Have your rear sam flashed to the new code. The battery drain problem is a known problem traced to the rear sam and it is a software fix.

Charge your battery. Until your battery is in top shape nothing will work right on your truck.

A gl in Zimbabwe? You are a brave man.

 

Thanks guys, I did actually go for the second hand option in the end although the garage I took it to said the front SAM was also faulty so had both replaced but all seems to be working now thankfully! I did have a good look/smell for moisture but couldn't see anything obvious so hopefully it won't re-occur...especially as the storms here are hectic!

Anyway, very helpful thanks and I'll ring on Mon to make sure they gave me the new software so the new batt doesn't go the same way. I'm debating selling both GLs as they're dbl the price here and buying Toyotas but it'll be a very sad day to part with them...

 

Wow GL in Zimbabwe! Awesome. Are you the only one there with GLs? How does the GL handle the off roading there? Do you have the off road package?

 

Nope not the only GLs - well Mercs in general are very popular here because of the old reliability so there are a few GL's around - well I've seen 2 so far. And yes one of mine has the offroad package...although honestly I can't tell the difference between them, and from what I read online does that only really mean that it has an extra plate on the undercarriage? But what of the 'optical' offroad package then? Either way they both handle very well being so powerful and the diff lock is great so I haven't been stuck yet although the rains have just started so we'll see...

 

Off road pack makes it so your air suspension can raise even higher. I think you also get the locking transfer case/ diffs.

Optical offroad may be referring to the metal skid plates on the front and rear bumpers that are visible (purely cosemetic).