There is a separate little motor I believe that turns the little gears. The gears are broken so the odo doesn't work

I have not checked the ovp relay yet. The tach does work after I bypassed the signal through the egr control module.

Whats the use of a speedo cable if its electronic .The cable is not turning ,The poster as fitted 2 other speedos to the car that are the same, so ,, take it for a spin and look at the cable simple ..see if it turns . I have repaired 4 of these W124 and W123 and i have never come across a motor inside yet.

Just been reading about the speedos for this car , and shure enough as above post they did make some fully electronic speedoes in 1981-2 .And after a time they went back to manual cable drives But i have never seen one of the electronic types speedos . The cause of most problems with the gears , is setting the oddo on the move .

This is the speedo head and how to remove the drive cable fron gearbox ..

Attached Thumbnails

   

And all the information i found about this is sitting on this forum .Just do a search .

Please stop arguing about a chassis you have no experience with.

The S class w126 is all electronic.

The cable is wires, not z spinning cable.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Op...
There is a power connector under dash above accelerator that must be plugged in...

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Hmm there is good chance it has come unplugged after I replaced the expansion valve. I'll look around for any connections.

Also I checked the ovp and it is working fine.

Edit: I'm not sure if this is relevant but my tach takes a few seconds after startup to actually work.

I took a quick look and didn't see any loose connectors near the accelerator.

All 126 chassis were electronic. It would be nice if people stopped arguing and paid attention. If you don't know what you're talking about, please stop putting out incorrect information.

There is no speedometer cable in a 126. They did not "go back" to using one either. The OP is having an electronic issue of some sort, plain and simple. The challenge is finding out WHERE the electronic problem is. Bickering about cables that don't existing on the car is progressing the discussion nowhere.

OP- See the attachments for a diagram of where your speedometer is getting power/ground/signal from.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

Hey Ncbenz,

If you would like to have your speedometer/odometer tested/inspected/repaired I would be happy to help out. I can bench test the unit for you and probably help you narrow down the problem.

I've seen a number of problems on these units including capacitor failures, fuses blowing (some model unit do have a small fuse built in), resistors getting hot and failing.


Just thought I'd chime in and make the offer!

--Kris

__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k

Hey thanks man. I'm going to try to exhaust some more testing but more than likely I will have to take you up on that.

I recently drove my electronic speedo on the bench. 1982 300sd is electronic and required a signal generator and 12v power supply.

Details here

Fixed 1982 300SD odometer slip at high speed

Getting it up and running on the bench was priceless for troubleshooting. My problem was in the stepper motor portion of the speedometer (that is the odometer I guess).

a drill won't work on this style of odometer.

__________________
79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles

Here is the schematic for the Speedometer. Page 120/2
https://www.startekinfo.com/StarTek/outside/12253/program/ETM/126td83-85.pdf

I noticed the impulse generator picks up a ground behind the instrument cluster. Usually grounds are where many of the electrical problems come from. Have you looked at the transmission end of things?

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )