Teambas

I am a true Mercedes Benz fan. I just purchased a very nice 1992 300SL. Only (Documented) 102,000 miles, about 4,000 miles per its 25 year life!
I picked up the car from the previous owner. Drove it home, 50 miles . Basically everything worked: Both Heated Seats, Cruise Control, Radio, Both Power Windows, Heat, Air Condition, Rear Window Defroster, etc. No lights on the dash. All seemed well. EXCEPT, I went to the car wash. The car went through fine. I put the car in park. (Left it running), as they vacuumed. When they were done, I got back in, & put the car in reverse, to back out of the spot, & IMMEDIATELY, the ASR, the ASD & the Snow Chains lights lit up!

I am not concerned; it was maybe a coincidence? Maybe the car does need front brakes? I have not brought the car to my mechanic (good friend) yet. But I always think it is good to "know" a little something beforehand. Since this is a 25 year old car, the dash lights are not the same as todays Mercedes. (My everyday drive car is: 2014 E250 Bluetec 4Matic)
Another friend told me that the "Snow Chains Light" not being able to be turned off, is a Transmission problem. He says, that will not let the car shift into 5th gear. Is that true? Again, I will have my mechanic look at the car next week or so.

Any help you can offer is certainly appreciated!

bobterry99

If the car drives normally, then perhaps a wheel speed sensor is failed or requires attention.

You are in New Jersey -- a state that has legalized gambling. Here is an idea. Get this friend to accompany you in your SL for a brief experiment.

Start the car and drive-off with the gear shifter in position "4". Attain a steady speed of 50+ MPH. Now propose a bet on whether the transmission will upshift to 5th gear when you move the shifter right to position "D". If he asks for odds, give them. Risk dollars to quarters or even nickels if necessary.

Teambas

I did just that. But it doesn't shift into 5th.

Teambas

I did just that. But it doesn't shift into 5th.

bobterry99

Your car has only 4 gears -- are you sure it's 5th you are missing and not 4th?

If you have lost 5th gear, then I would begin diagnosis by reading codes from the transmission ECU. Depending upon codes that were found I might remove the electrical connector to that ECU and check input signals with a multimeter. On the chance that all the problems you have described are somehow related to a single cause, then I would troubleshoot the transmission problem first, since for me its diagnostics are simpler.

Teambas

Everything I have read states the car has 5 forward gears, not 4.
Yes, my mechanic (friend) will read the transmission ECU. I know it's probably (hopefully) minor.

bobterry99

According to your prior post operationally you have only 4 gears. An electrical problem can cause the transmission to not shift into 5th, or it can cause it to never shift into 4th (3rd gear upshifts to 5th).

hogdad

If your still interested the car has 5 gears. It starts out in 2nd. 5th gear is controlled by an ( somewhat adjustable) module under the hood on the passenger side. If you need to know where it is let me know Ill take a pic of mine.

Teambas

A picture would be GREAT!
I have not "fixed" it yet, because it is the winter, & it is not driven in the winter.
However, Spring is coming up really quickly. So I would love to get it taken care of ASAP.
Thanks very much!
Joe

hogdad

https://www.ebay.com/itm/90-91-92-93...xZyg2O&vxp=mtr

This is the part, it is under a screwed on big black plastic cover on the right hand passenger side firewall Right by the hood hinge - When I go out later Ill take a pic of the cover for you to show you where it is.

hogdad

Im not selling it, Im just saying i would try and adjust your first and if you or a mechanic determine thats what wrong, here is a source to find one...

hogdad

https://www.bing.com/images/search?v...=67&ajaxhist=0
here is the location, Its one of these two modules if i recall correctly..this is an internet pic i found

hogdad

I think the pic is a different car and I would disregard the N30 or whatever that says, but this is where it is on my 1990 300Sl- hope this helps when your ready to drive it in the spring, regards

Insbroker

bobterry99

It starts in either 1st or 2nd gear depending on the action or position of the shifter.

Typically, the transmission starts in 2nd gear. But if the vehicle is at rest and the shifter is moved to "2", then the transmission shifts to 1st gear. It remains in 1st even if the shifter is subsequently moved to one of the other forward-gear positions.

Back in the day Mercedes rationale for the 2nd-gear start included reducing "creep" at idle and improved fuel economy.

Insbroker

Thank you for that. After I read the first post I finally found the gear I had been looking for! I thought it was a dog off the line, but its much better starting in first! thanks.