vladc77

I got a nasty surprise from my Mercedes GL450. Suddenly, my front and rear wipers stopped working while washer system is working fine. In addition, I started getting SRS error. Then, I also found out that cigarette lighter and glove box light has no power anymore. It seems like all started at once. I did some investigation and still cannot find the source of the issue.

1. The wiper switch brings rear wiper icon on the instrument cluster while I engage it. It seems like the combo switch is still working.
2. I checked wiper on/off and 1/2 relays and they seems to be working properly. However, the wiper on/off relay does not click while it is in the fuse box. It works well outside fuse box when I feed it even with 9v battery.
3. I checked the voltage on the lines to the wiper on/off relay and found out that lines 85 - 86 get 4.5-5.2v only. However the line 30 and 87 get 12.
3. I connected directly 30 and 87 and wipers started to work.
4. I checked the front SAM on all actuations available and all of them work solid, except wipers.
5. Removed тhе front fuse box and checked all of thе connections. All of them аrе in a great state.

Now, I am lost and not sure what is causing the issue. I still cannot solve the problem. Wipers do not work. The only finding is that one of the lines is getting 5v instead 12v. I also do not see the relationship between SRS, cigarette lighter and glove box light.

I am wondering if anyone had the same issue and were able to solve it. Any advice is highly appreciated. Thank you!

islandbeef

It could be the steering column module. Apparently, it may be a short. From what I've heard in the past, these type of problems usually end up at the Stealership Service Center.

alx

They are all powered by the front sam.

But... Check the fuses again : http://www.mercedesmedic.com/gl-fuse-chart-x164/

vladc77

I will check all fuses again. I did check the fuses before and all looked fine.

I wanted to ask about front SAM. I used Star Diagnostic tool to perform all available to SAM actuations including wipers. The instructions say to turn off wipers combo switch and turn on Terminal 15R (ignition position to on). Then, I used computer to start/access wipers. When I click F3 (Wipers On/Off relay), then no click sound from the relay, but switch graphic in the program goes to position ON. When I used F4 (wipers 1/2 relay), then I hear the click sound from the relay. I am trying to figure out if front SAM can be a problem. My logic is that I can use SAM to switch relays, SAM sends commands to do it. The relay on/off does not respond. The other functions available to SAM are working perfectly. As a result, I ruled out SAM as a failure. DAS provides a list of possible problem where SAM never in the list. The only suggestion is to check On/Off relay and lines from SAM to X25/2 component and from X25/2 to the front fuse box. I;d like to hear your opinion about front SAM. Based on all info provided, would you also make conclusion that SAM is not a problem or not? I tend to believe that maybe relay is a problem but I checked it outside the the fuse box and it seems like it is working correctly. I also replaced my relay with another relay but results the same.

vladc77

Yes, it potentially can be the issue. I checked the wipers without the steering wheel involvement via diagnostic tool and results the same. As a result, I need to fix something else before going to this route.

vladc77

Alex, I tent to believe that it is the front SAM issue. I removed front SAM, got access to the board and found out that some pins on few microprocessors were covered with some sort of dirt. I believe the water got in somehow. I cleaned them and now all looks like new. I put it back but the problem remains the same.

I may need to get new SAM but wondering if I may be able to recover it by reprogramming it as fresh new unit using star diagnostic. My idea is that it is still may be a good hardware piece but something happened on firmware level. Do you have any opinion on that? Thank you in advance!

alx

If you can read the front sam the software is ok. This is a complex issue. I would pay the dealer for one hour of troubleshooting to pinpoint the issue. Money well spent imo.

Don't remember, but I believe your front sam also needs scn coding if replaced.

vladc77

Thank you! I believe I need to order new SAM. I am not sure if more cleaning of SAM's circuit board will help anyhow. However, I am not sure yet but I heard that SCN coding is possible in SCN offline mode too for front SAM. I will need to check on it.

OC BIG B

Did you happen to check the battery compartment under the passenger seat for water? I have had water get in there and cause some electrical havoc. I still have to find the source of the water. Maybe the moon roof drains or A/c drain, not sure yet.

vladc77

Yes, I checked that area. Everything is clean.

vladc77

I wanted to share my experience resolving the issues I described earlier.

I went through the standard diagnostic procedures using Xentry/DAS. At the end, the only pointer from DAS was is to replace the faulty front SAM. However, I accidentally found out that if someone will occupy the front passenger seat, then everything like a magic will go back to normal and work as usual including the front and rear wipers, SRS error gone, cigarette lighter and glove box light. I checked it again without a passenger seat to be occupied and everything stopped working. Then, I pushed hard the seat bottom cover few times and everything started to work. My conclusion is that SAM is not in faulty and the SRS/weight sensor has a faulty. I am going to check all of the connections there and replace the sensor mat if necessary.

Unfortunately, the sophisticated diagnostic tool as Xentry did not help here at all. In addition, I have trouble understanding how faulty SRS sensor mat affects the work of front/rear wipers. To me, it is a bad design or some sort of mystery. I hope it helps.

vladc77

Still looking for the tips. Any help is highly appreciated.

Everything worked great for a couple of days and then it stopped working again. The first suspect was the seat sensors. Seat buckle seems to be working. At least, I don't see any unexpected errors on the dashboard. I removed the passenger seat out of the car and checked/cleaned everything there and was not able to find anything suspicious. Finally, I tested the weight system via STAR/DAS. All sensors communicate with STAR/DAS and provide the correct weight values. No issues reported. Now, I am sort of lost with this German engineered mystery. Initially, I thought the front SAM module is the problem but then all worked fine for few days. Das does not see any issues with SRS at all. I just don't know what is the failure. Still looking for a clue. Thank you in advance.

alx

i dont think they are related in a logical way, but simple physics. you prolly have some harness under the pass seat / in/around cushion and pushing the cushion unbinds harness and all starts working. look in there. it is pressure/ deformation related- not circuit- related... wiggle things, remove seat look underneath... you get my idea

vladc77

Thank you Alex!
Yes, I agree it should be some contact issue. I hope that my front SAM did not play a bad joke on me and did work just intermittently exactly at the time I had a passenger on the front seat. I sort of ruled out front SAM. Unfortunately, this issue is very difficult to trace.

I took the passenger seat apart and cleaned the weight sensors as well as checked all of the wire contacts. No results. The weight sensors worked perfectly anyway. I don't see any harnesses below the seat other than to the seat. I will keep looking.

vladc77

I finally found out what was the issue. It is all because of the faulty relay in rear SAM - (K) Circuit 15R relay with the part number Mercedes 002 542 2619.

Ironically, the relay was working intermittently. As a result, I did much more work that I should be. I checked this part as the first step. During that time it worked. I hope it will save you a time and money.

DaBenzGL550

How does one access the rear SAM? I'm having trouble finding it. I need to check it due to a Malfunction warning for the air matic suspension, and also for a/c not cooling.

easylife2002

Vladc77, I am having these same issues you described in your post. I already replaced the same fuse or relay you mentioned but no success unless if I didn't replace the right one. I actually bought it from the dealer in order to make sure I got the right relay. Please any help from you will do. My email is aoel2006@aol.com