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michel bertin
Veteran
Date registered: Jun 2006
Location: SFO Bay Area, CA
Vehicle(s): '02 G500, '14 G550
Posts: 124
| transmission output speed sensor
2002 G500, had the transmission today go into a mode where it stays into a fixed gear (maybe different than limp mode, but likely feels the same). Took the G to my trusted mechanic (I was only 1mi away). No check engine light on while I was driving.
My mechanic later restarted the G, the check engine light came on, the transmission was then working perfectly normal. Later today, the G was just fully normal, no light or transmission behavior.
2 codes showed up:
- B49 transmission output speed sensor (mounts externally to the rear of the transmission). I understand the G is the only Mercedes vehicle to require that additional speed sensor for the 5-speed transmission. If the trans does not get a speed signal, it stops shifting. Very easy to replace though.
- N36 transmission output speed sensor ballast (located in the rear under the CD changer). This is the relay that controls the sensor, has a long cable that routes through the car and takes more labor to replace.
Apparently, at least one of them at some point today was "bad" and caused the transmission to stop shifting. Don't know which one.
I searched the forum and did not find comparable posts, nor do I remember reading one about these parts.
Looking for input from P3 members please.
I very likely will get both replaced just because I don't want this to re-occur while on a highway or on a trail.
Thank you in advance,
Michel
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G-AMG
G-Class DIY Host
Date registered: May 2006
Location: South Texas
Vehicle(s): '04 G55, '80 280GE, '99 S420, '98 E320, 2011 E350
| Re: transmission output speed sensor
99.9% probability it is the "Electronics Pack"/Conductor Plate, gone bad.
The Repair is the first one listed in the DIY section. |
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AlanMcR
Expert
Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
| RE: transmission output speed sensor
Got to agree with G-AMG. The symptoms point to the conductor plate, a relatively common failure. The part that fails on that plate is also called a speed sensor. What were the observed numeric codes?
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michel bertin
Veteran
Date registered: Jun 2006
Location: SFO Bay Area, CA
Vehicle(s): '02 G500, '14 G550
Posts: 124
| RE: transmission output speed sensor
Thank you G-AMG and Alan. Not sure this is the same issue here though.
Code is P2206. It specifically identifies the external output speed sensor. We have no indication of an issue with the internal speed sensors. My mechanic says that they already have seen the issue with the external speed sensor a number of times. Also my transmission shifts wonderfully smoothly, partly because of the frequent oil/filter changes I have had done. |
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Ertech
Veteran
Date registered: May 2016
Location: Montreal CA
Vehicle(s): 2011 G550
Posts: 156
| Re: transmission output speed sensor
Got the same problem. Anyone else had this?
Thanks |
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michel bertin
Veteran
Date registered: Jun 2006
Location: SFO Bay Area, CA
Vehicle(s): '02 G500, '14 G550
Posts: 124
| Re: transmission output speed sensor
I ended up having both the sensor and the relay replaced for ease of mind. The latter requires more labor.
Never had the problem again. The 5 speed trans on this G shifts wonderfully smoothly, but I did get the oil and filter changed frequently since it was new. |
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Ertech
Veteran
Date registered: May 2016
Location: Montreal CA
Vehicle(s): 2011 G550
Posts: 156
| RE: transmission output speed sensor
Isn't the relay super easy to replace? |
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AlanMcR
Expert
Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
| RE: transmission output speed sensor
Ertech - 12/11/2016 8:16 PM Isn't the relay super easy to replace? Yes it is. The problem might be finding it. Just today I was browsing around the EPC and ran into the description of a "mystery module" I'd been wondering about. It turned out to be this speed sensor relay. Didn't know I had one.
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ILIAN
Veteran
Date registered: Sep 2014
Location: Boston MA
Vehicle(s): 2000 G500 1999 CL500
Posts: 181
| Re: transmission output speed sensor
Where exactly is that located Alan? |
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Ertech
Veteran
Date registered: May 2016
Location: Montreal CA
Vehicle(s): 2011 G550
Posts: 156
| Re: transmission output speed sensor
it is located where the cd player on the rear left . its one of the 3 relays < the taller one>
thanks |
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AlanMcR
Expert
Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
| Re: transmission output speed sensor
ILIAN - 12/13/2016 8:59 PM Where exactly is that located Alan? See above for the 2001+ MBUSA models. For pre-MBUSA, it is in the electronics box under the hood (see arrow below). Seen from the side is a funny looking thing, about 3" tall and the plastic has a pattern of indentations making it look a bit like a toy apartment building.
Edited by AlanMcR 12/14/2016 1:20 PM
 (K40-3-Replacement.JPG)
Attachments
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 K40-3-Replacement.JPG (81KB - 26 downloads)
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ILIAN
Veteran
Date registered: Sep 2014
Location: Boston MA
Vehicle(s): 2000 G500 1999 CL500
Posts: 181
| Re: transmission output speed sensor
Thanks! |
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