Go Back  MBWorld.org Forums > Mercedes-Benz SLR & SL Roadsters > SL-Class (R129)
1990 300SL not shifting into overdrive 5th gear >

1990 300SL not shifting into overdrive 5th gear

Notices
SL-Class (R129) 1990-2002: SL 280, SL 300, SL 320, SL 500, SL 600, SL 60 AMG

1990 300SL not shifting into overdrive 5th gear

 
Old 04-05-2013, 08:11 AM
  #1  
Newbie
Thread Starter
 
Join Date: Apr 2013
Location: Tampa, FL
Posts: 3
Likes: 0
Received 0 Likes on 0 Posts
300SL
1990 300SL not shifting into overdrive 5th gear

I recently purchased a 1990 300SL R129 automatic with 60K actual miles. The car looks like it just came off the showroom floor. When I was test driving it everything worked fine until I got it home and after a couple of days I noticed that it was shifting into overdrive. It will when I first drive the car but won't once it warms up.

I took it to the local MB dealer (Fields) and they replaced the solenoid but that didn't do the trick. I complained to the service manager that I was out $560 and the tech explained to me he knew nothing about this vintage.

Two weeks later it is still at the dealership and they still have no clue. The cruise is working. Shifting from 4th to 5th doesn't work. They reviewed all the suspected problems and I was wondering if anyone else had this problem. BTW, they aren't charging me anymore money!

Last edited by pristine300sl; 04-05-2013 at 08:33 AM. Reason: error
pristine300sl is offline  
Old 04-07-2013, 01:21 PM
  #2  
Newbie
 
Join Date: Oct 2012
Location: Central Nevada
Posts: 4
Likes: 0
Received 0 Likes on 0 Posts
2001 SL 500
I'm not 100% sure with the 300 but I think 1990-1995, SL's only came with 4 speed automatics.
certz656 is offline  
Old 04-07-2013, 05:43 PM
  #3  
Newbie
Thread Starter
 
Join Date: Apr 2013
Location: Tampa, FL
Posts: 3
Likes: 0
Received 0 Likes on 0 Posts
300SL
I will take a pic of the shifter, but it does have OD. The dealer is still working on it.
pristine300sl is offline  
Old 04-14-2013, 04:09 PM
  #4  
Newbie
 
Join Date: Jul 2007
Location: Minneapolis, MN
Posts: 1
Likes: 0
Received 0 Likes on 0 Posts
1991 Mercedes 500SL
1990 SL 300 transmission

The 300's did have a 5 speed auto trans, but the V8's only had the 4 speed auto.
Doctor2687 is offline  
Old 04-16-2013, 03:25 PM
  #5  
Newbie
Thread Starter
 
Join Date: Apr 2013
Location: Tampa, FL
Posts: 3
Likes: 0
Received 0 Likes on 0 Posts
300SL
It is the 722.5 transmission. I was able to get it working better?...by putting in a new crusie control module, not I have cruise control. I also checked the three prong plung and actually moved it away from the valve cover. Shifted perfectly this morning, crusie works perfect but after stop and go driving, it stops working again. I removed the N15/1 module and it skips 4th and goes directly to 5th smoothly which rules out a tranny probelm. I don't have the proper diagnostic equipment so off to the shop.
pristine300sl is offline  
Old 10-16-2013, 10:03 PM
  #6  
Newbie
 
deak60's Avatar
 
Join Date: Oct 2013
Posts: 1
Likes: 0
Received 0 Likes on 0 Posts
Mercedes 300 SL 91
Deak

I have the same problem as you on your 300SL with it not shifting into 5th gear. Did you solve the problem. It is a 91
deak60 is offline  
Old 12-09-2014, 04:53 PM
  #7  
Newbie
 
Join Date: Dec 2014
Posts: 1
Likes: 0
Received 0 Likes on 0 Posts
1990 300SL-24 5-spd auto 722.5
Smile ME TOO!! ME TOO!!

Pristine 300sl & Deak60 ~

Ive got the same issue. What did you guys do to remedy inoperable 5th gear?

THANX MUCH : )
kramps is offline  
Old 10-15-2018, 12:41 PM
  #8  
Junior Member
 
Join Date: Apr 2018
Location: Calgary
Posts: 29
Received 0 Likes on 0 Posts
'90 300SL , '05 S500
Does anyone have an update on this - I've the same issue - someone told me their is a small switch that contacts the shift lever in the console that could be an issue - I'm going to gingerly remove the beautiful wood console to see if I can see anything. This car only has 74,000 KM ( 46,000 miles ) on the highway it's revving at about 3500 RPM @ 110KPH ( 65 MPH) which seams to be high... someone mentioned the N15/1 module removing to trick it moving into fifth ( where might that reside )

I just had the transmission serviced - new fluids and gaskets etc...
DM914 is offline  
Old 10-15-2018, 04:46 PM
  #9  
Junior Member
 
pjacobs55's Avatar
 
Join Date: Nov 2017
Posts: 19
Received 4 Likes on 4 Posts
MY2000 SL500
Red face

It took me a while to figure out where overdrive (5th) was. I simply moved the shift lever over to the right and it switched up! Keeping it on the left side of the "Drive" slot keeps it in 3rd or 4th, depending on which trans you have.
But this may not be your problem ... just mentioned it because I had a "Doh" moment when I read this in the owner's handbook.
pjacobs55 is offline  
Old 10-15-2018, 11:03 PM
  #10  
Member
 
Join Date: Jun 2017
Location: Austin, TX
Posts: 171
Received 20 Likes on 17 Posts
1997 SL600, 2017 AMG GTS
Did the 1990 have a 5-speed? I thought it was 4-speed.
sneezix is offline  
Old 10-17-2018, 12:32 PM
  #11  
MBWorld Fanatic!
 
Join Date: Jan 2006
Posts: 1,070
Received 131 Likes on 113 Posts
'03 SL500, '03 SL55, '00 S500, (5) R129s
Originally Posted by DM914 View Post
someone mentioned the N15/1 module removing to trick it moving into fifth ( where might that reside )
It resides with the other electronics under a plastic cover in the right-rear engine compartment. Atop it is a black plastic knob which you twist to remove it. The module should have a white label which reads "HGS".
bobterry99 is offline  
The following users liked this post:
DM914 (04-24-2019)
Old 11-04-2018, 04:23 PM
  #12  
Junior Member
 
Join Date: Apr 2018
Location: Calgary
Posts: 29
Received 0 Likes on 0 Posts
'90 300SL , '05 S500
I will try to remove the module and see if it moves into 5th - My gear selector has a D and then if you move lever to the left it locks into 4th - driving at HWY speeds no difference in RPM in either 4 or D ( which should be 5th )

I do have a Obd1 code reader but I do don't have any dash lights on - will the code reader identify a problem with a part even if no dash light is on?

the local dealer hasn't been much help as they don't know much about these vintage units,

The solenoid they speak about will that throw a code that you can read to know that is your issue... Is the solenoid external to transmission or do you have to pull the pan?
DM914 is offline  
Old 04-24-2019, 09:38 PM
  #13  
Junior Member
 
Join Date: Apr 2018
Location: Calgary
Posts: 29
Received 0 Likes on 0 Posts
'90 300SL , '05 S500
so i pulled the N15/1 module and the car skips right into 5th when driving skips over 4th. so my question is do i replace that module? or do I pull the console out to check the operation of the switch? i can find the replacement module fairly easy but don’t want to replace if that part isn’t a common issue...
DM914 is offline  
Old 04-24-2019, 09:51 PM
  #14  
Junior Member
 
Join Date: Apr 2018
Location: Calgary
Posts: 29
Received 0 Likes on 0 Posts
'90 300SL , '05 S500
mine is a 300sl and it has the 5 speed the V8 cars had 4 speed
DM914 is offline  
Old 04-24-2019, 10:45 PM
  #15  
MBWorld Fanatic!
 
Join Date: Jan 2006
Posts: 1,070
Received 131 Likes on 113 Posts
'03 SL500, '03 SL55, '00 S500, (5) R129s
Originally Posted by DM914 View Post
so my question is do i replace that module? or do I pull the console out to check the operation of the switch?
I would see if the HGS module is receiving the signal from the "D" switch on the shifter gate.

You remove the electrical connector to the HGS switch and use a multimeter to check continuity between sockets #17 and #21 with the selector in "D" and also in "4". In one position you should see a short circuit and in the other an open circuit.

If no signal, then I would suggest that you remove the "D" switch and clean its contacts. If you have the signal, then the control module is suspect.
bobterry99 is offline  
The following users liked this post:
DM914 (04-25-2019)
Old 04-25-2019, 08:28 AM
  #16  
Junior Member
 
Join Date: Apr 2018
Location: Calgary
Posts: 29
Received 0 Likes on 0 Posts
'90 300SL , '05 S500
thanks much .. i’ll will give that a try...
DM914 is offline  
Old 05-31-2019, 11:13 PM
  #17  
Junior Member
 
Join Date: Apr 2018
Location: Calgary
Posts: 29
Received 0 Likes on 0 Posts
'90 300SL , '05 S500
I tried removing the module and checking the continuity on the sockets when moving the shifter from D to 4th and yes the switch at the shifter does work - so the HGS module is bad - I bought a used replacement and installed still the same problem won't shift into 5th gear - so my question is do you have to perform some kind of "reset" to initialize the new module or should it just work when installed - I'm hoping I don't have a second dud unit... but maybe I just need to do a reset ? if so what is the procedure to do one... thanks much
DM914 is offline  
 

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 

Thread Tools
Search this Thread
Rate This Thread
Rate This Thread:
You have already rated this thread Rating: Thread Rating: 0 votes,  average.

Quick Reply: 1990 300SL not shifting into overdrive 5th gear


Contact Us - About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: