Mercedes-Benz Forum banner

280SL Speedo Sending unit.

11K views 68 replies 14 participants last post by  grahamandbea 
#1 ·
'83 280SL 5 speed. Speedo and odo were working intermittently. Then all are dead.

Anyone know where the elec. sending unit for this one is? Trans? Dif?

Also could the problem be in the head unit. Any fuses on this circuit? I don't have the cd or EPC on this puter.
 
#4 ·
Thank God... I was afraid we'd failed you again. :D

It could well be fuse 5 which powers both. The speedometer & tach have different inputs. The tach coming from the ignition switching unit and the speedometer from an impulse transmitter on the transmission.

Keep in mind this is for a 380sl auto....

BTW, love the new avatar!
 
#7 ·
Hello.

I own the 1983 MB 280 SL. 5 Sp.
VIN WDB 10704210014754 Euro. Grey market.

Recently, the speedo/odo/trip milage all stopped moving.
They were intermittent for while.

MB Classic center says speedo is elec. If so, where is
the sending unit ? Is fuse # 5 involved ?
BTW. My fuse box listing is in german. Does anyone
have an English fuse list you could post ?
It does seem as if one issue is stopping all the
speedo/odo/trip indicators.

The fuse panel is located on the pass/side footwell area
so it necessary to crawl down there to see the fuse
and then discover the list is in German....

TIA.

Dr Rx. In sunny Northern Calif.
1967 MB 250 SE Coupe
1983 MB 280 SL 5 Sp
1991 MB 300CE
1950 MG TD
 
#8 ·
If you will carefully take the fuse panel cover and remove the paper fuse list you will see that the reverse side is printed in English...I also have a 280 SL 5 spd....I have had intermittent speedo but I don't think it's a fuse issue...I have not been underneath to check for sending unit off the transmission but I remember someone saying something to that effect...
 
#12 ·
Check / replace / clean the fuse.
Pull the gauge cluster check the seating of the plug.
While the cluster is out........add a ground wire from the cluster housing to something steel under the dash.
If that solves nothing.....then I would consider crawling under the car.
 
#14 ·
To remove the instrument cluster, must the steering wheel be removed ?
I wonder if Rusty is lurking. He might even have the part...
Fellow lister provided # 1075400508
I like simple. Will do the fuse # 5 trick first.
While there, I'll turn the list from German to English, if it's accurate.
My tach also works fine...

As this spins out, I'll post more info.

Many tks for the replies.
 
#15 ·
Just in case you can not remove the German side paper so you can see the English names for the fuses, here is what it says on my 1977 280SL.
1 1 Clock, antenna, glove box light, boot light, foot well lights, doom light, entrance light – 8A
2 2 Auxiliary fan – if equipped – 16A
3 3 Power window motor (front right) – 16A
4 4 Power window motor (front left) – 16A
5 5 Horn – 16A
6 6 Blower motor – 16A
7 7 Heated rear window – 25A
8 8 Back up lights – 8A
9 9 Fog lamps, rear fog lamps – 8A
10 10 Stop lamps, turn signals, instrument cluster, tachometer – 8A
11 11 Windshield wiper, windshield washer pump, optical horn – 16A
12 12 Cigar lighter – 8A
13 13 Tail/parking/standing light right, lighting for license plate, dash board, shift indicator, hazard warn flasher. – 8A
14 14 Radio – 5A
15 15 Fog lamp, rear fog lamp – 8A
16 16 Tail/parking/standing light left, parking tail light left – 8A
17 17 High beam right, high beam indicator – 8A
18 18 High beam left – 8A
19 19 Low beam right – 8A
20 20 Low beam left – 8A

Jerry - 1977 280SL (Euro) Edgewood, Washington
 
#18 ·
I re-checked the sheet on the fuse panel that indicates 16A and the other item listed is "schiebedach" or as interpreded = "Sun Roof" of which I did not figure many R107 convertibles had, so I did not include it. The main item was "Horn" which in German and English is "Horn".

Jerry - 1977 280SL (Euro)
 
#21 ·
If it is the original MB steering wheel then yes it does have to be removed to remove the instrument cluster. This applies to all 107's.
A paper manual is not available for the 280. You need an M110 engine manual and a 107 Chassis. Manual.

Cool, you have a manual trans.
 
#22 · (Edited)
As for service manuals I use the Haynes Mercedes-Benz 280/123 series #983. I purchased it from a used book store for $3.95 + tax. For the body etc. I use the Haynes Mercedes-Benz 350 $ 450 manual # 63030 (698). I don't remember where I got it but it was about 6 or 7 bucks used. An nother good manual is the Bosch Fuel Injesction by Charles O. Probst published by Robert Bentley and covers all Bosch systems for testing and repair. This manual cost me about $25 several years ago.
 
#24 · (Edited)
Many tks for the Manual info/data.
While this 280 SL is a 5 Sp, it is not a swift MB...
My 88 VW Cabriolet. 94 hp. 5 Sp can zip past the MB at all speeds.
Is there a governor/restrictor on the Euro/Grey Market 83-280SL ?

The MB has been adjusted to meet the Calif emissions requirements
and has passed without any problems or adjustments during the past
8 years. The engine purrs and the exhaust hums, but it's a bit slow
for a 6 cylinder FI, 185 hp.

Your thoughts..
 
#25 ·
Make sure the parking brake is off.





Kidding.





You want more acceleration from your SL? Let the revs get up there before shifting.
Mine seems to really surge between 3300RPMs and 4500 RPMs.


Off the line? Well, I'll let you be the judge.


 
#29 ·
re: 280sl 107

I have the same car and same problem and same characteristics
as others with intemitent operation,

I was told by my indy that what may cure the problem is a new wireing
harness and thats if one can be located.

Sturg

'84 280sl 5 speed stick - 192k:D
 
#30 ·
vacuum/electric speedometer

I have the same car and same problem and same characteristics
as others with intemitent operation,

I was told by my indy that what may cure the problem is a new wireing
harness and thats if one can be located.

Sturg

'84 280sl 5 speed stick - 192k:D
only problem is i can't seem to figure out what anything is, is electrical behind the instrument cluster but from the tranny up into the engine compartment it is a vacuum line. i'm sure if i can find the component that changes it from vacuum to electric and change that out i could solve my problem. any ideas what it is that changes it from vacuum to electric or if there is a way to convert it all the way to electric without having to take apart the trans?
 
#33 ·
Speedo trouble

its an auto, the vacuum line comes up into the fuse box area and the vacuum line continues through there and through the firewall but where it changes to electric i can't seem to find it. mech.ox@hotmail.com i can send pics of what i'm talking about. would probably help out so much more. anyways, no one i talk to seems to know anything about this. they have never heard of a vacuum operated speedo even if only part of it. is there a way i can take out the vacuum from the trans and change it to electric without having to take apart the trans?
 
#35 ·
its an auto, the vacuum line comes up into the fuse box area and the vacuum line continues through there and through the firewall but where it changes to electric i can't seem to find it. mech.ox@hotmail.com i can send pics of what i'm talking about. would probably help out so much more. anyways, no one i talk to seems to know anything about this. they have never heard of a vacuum operated speedo even if only part of it. is there a way i can take out the vacuum from the trans and change it to electric without having to take apart the trans?
The vacuum line operates the gas economy gauge at the bottom of the instrument cluster ....the speedo gets its power/ pulses through the cable that plugs into the the center of the instrument panel in the back....everything else including the tach gas gauge etc are operated thru the multi-pin connector on the back (about the size of a silver dollar)
 
#39 ·
ok i looked again one of the air hoses goes down to the doors but another couple go through the firewall behind the dash. i've uploaded pics not sure if they will help. but maybe
Okay in pic #4..that is the connector for the speedo there should be a single plug that slides onto that...do you have a pic of the front of your instrument panel and the entire back of it...please post if possible
 
#38 ·
speedo trouble

also to mention i do have a manual on the vehicle but it shows nothing of the speedo other than "take caution when taking out instrument cluster to unplug speedo cable" thats it no other mention in the book what so ever on the speedo. its a chilton manual so u know
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top