onewhippedpuppy

I'm a long time Mercedes guy, two of my past favorite cars are a C36 AMG and C63 AMG and I've always loved the G-wagon. When I had the chance to get a great deal on a 2002 G500 with about 100k I couldn't say no, even though it was sight unseen. It arrived last night, and while the cosmetics are pretty good it has an abundance of problems. Go figure, right? For starters, it needed a jump to get off of the transporter on Tuesday. The battery was totally dead and wouldn't take a charge, period. I replaced the battery today, and the fun really started. Going down the list:

Stuff that doesn't work:
Turn signals
Fender top lights
Left front side signal
Both side marker lights
Left rear side marker light
Left rear tail light
Left rear window
Wiper motor buzzing, wipers don't work

Other issues:
SRS system fault message
Front left marker lamp message
Right tail light won't shut off, ever.
Finally, it is in limp mode. It starts and runs great but the transmission won't shift out of 2nd. Won't shift manually, transfer case is in H, no CEL.

No codes found with my OBD2 reader, I'm going to order a STAR reader tonight. Based on common G issues, any suggestions? Obviously the limp mode is a concern, but the lighting is odd as well. Worthy of note, the side signal lights have been converted to the later style G LED lights.

aerG500

More than likely you have a bad front & middle SAM (Signal Acquisition Module) unit, i dealt with it with my last G... learned my lessons the hard way... There are three in total in the w463 and they are about $1000 each. The SAMs control the vast majority of the lighting issues you speak of. Sadly, simply jump starting the G with the key in the ignition is actually enough to blow a SAM. Do yourself a HUGE favor and take it to either a Factory Dealer or a highly compatent w463 G independent specialist if you have one close by. Forget about the high labor charge the dealer will charge... if it's not done right, you'll end up being thousands in the hole.

Wiper motor sounding but not working is probably as simple as the nut at the base of the wiper arm having loosened. When you tighten it, use a drop of blue locktite as those loosen over time and actually allow water into the driver & passenger footwell when it rains too.

Left rear window not working... does the actual motor work (do you hear it in the door)? if so, you just need a new regulator. Get used to it as you will end up replacing all four. VERY common. Factory ones are about $500 each, there are aftermarket window regulators from Taiwan available for about $125-150 each (check eBay) and they work just fine.

For the limp mode, do some searches on google and you'll find the TCU reset procedure. seems to work marvels.

AZN Optics

obvious question, but you checked to make sure none of the fuses were blown right?

onewhippedpuppy

Thanks for the replies! I'll check the wiper nut. The rear window I suspect to be the motor, it is silent when I try to operate it. I've found several sources for the motor vs the expensive motor plus regulator.

After doing some research I was fearing the SAM module, all of the lights in question show as an "elektronik" fuse which appears to be internal to the SAM. aerG500, do you happen to know what functions correspond to which SAM? That is a piece of info that I haven't been able to find online.

I have ordered a more advanced OBD reader that can access all factory modules and gets good reviews from Mercedes guys, I'm hoping that will provide some clarity.

onewhippedpuppy

Nevermind, posted here: http://fourbyfourclub.com/Manuals/W463249Electrical.pdf

Hopefully that helps if someone else encounters the same issues. Per the diagram, the outside lighting issues would point to bad front and rear SAM modules.

onewhippedpuppy

Ran codes today, findings:
Not surprisingly the rear SAM module is not communicating.
Front communicates with no codes but I still suspect an issue, as many of the lighting functions that go through the front SAM are not working.
SRS shows a light but there are no codes.
Transmission shows no codes but is still stuck in 1st gear. Looking at the live data it shows selected gear correctly as I manipulate the lever but the target gear and actual gear stay on 1.
There is not a light for ESP but there is a code for the steering angle sensor calibration.

So any suggestions? I'm pretty well convinced that I need to replace/repair both front and rear SAM modules. What would cause the transmission to stay in 1st despite no codes? Why is there an SRS light but no code? Why is there an ESP code but no light?

Carnivor

We're your issues ever sorted out?

JCHbenz

Hi, I know your post is old, but I have almost the same problem and need your kind reply.
I bought a 2002 G500, black car with 137K miles. I have the same issues with the turn signals, rear lights, rear right will not turn off, SRS on dash, etc.
I was wondering if you ever solved these issues and if you had to change any of the SAM modules.
I appreciate very much your response.
jackcastro2000@hotmail.com
Thanks!!

onewhippedpuppy

It has been a LONG time but I believe replacing the rear SAM corrected most of the issues. I had to get the exact PN from Mercedes and have them code the module to my VIN.

Floobydust

Yes, I'm sure properly coded, replacement SAMs addressed most everything except limp home mode. On the 722.6 transmission in an '02, 2nd gear limp home mode is usually the conductor plate, the output speed sensor on the back of the transmission, or a damaged TCU from a leaking bulkhead connector.

JD101b

I'm a bit of a broken record on this, but check the truck for rust. Even well sorted and maintained/cleaned ones are prone to it. Some places to consider:

-Under the bonnet sound deadening. I just removed mine and the entire underside is covered in light surface rust. My guess is, moisture gets trapped in between the sound deadening and sheet metal and corrodes it over time.
-Along the door sills.
-Along the windscreen weatherstripping. Moisture gets trapped in here and can't drain out. I find that applying WD-40 Corrosion Inhibiting spray behind the stripping is an effective way of preventing rust. This is NOT regular WD 40. Here is a link: https://www.wd40.com/products/corrosion-inhibitor/
-Along the bottom of the doors. There are small drainage holes in which you can insert a straw and spray the aforementioned WD-40 to coat the bottom of the doors.
-The metal surrounding the moon roof.
-The metal surrounding the rear door hinges.

A good oil coating will go a long way to slow/stop rust formation. If you already have rust areas, spot treatments followed by oil application is your best bet, along with keeping the truck in a dehumidified garage. A couple of fans to circulate dry air under and over the truck will help to dry out any pooled moisture.

sxvohra

Hey, im dealing with the same issue, i was wondering if changing the rear SAM fixed the transmission as well?

were the electrical gremlins and transmission issue all caused by 1 problem?

ANY help would be greatly appreciated!!

Thanks

JD101b

Check for rust ASAP: https://mbworld.org/forums/g-class-w...lass-rust.html