90' 560SEL speedometer problems
 

Hello everyone,

My buddy just got a 560SEL. The speedo doesnt work. I tried two different clusters and it would just seem that there is no signal coming up from..wherever it originates.

He sent it to the shop as it needed some other things worked on. We had them look at it and they said that the transmission was worked on and something was put in wrong inside the transmission.

I've been looking through all my documents for the location of the pickup sensor. Originally I thought it was actually on the differential however the FSM's Electrical Troubleshooting Manual tells me is on the the transmission, left side rear.

I also have the 722.3 transmission manual and haven't found any mention of the pickup sensor.

Any one have any ideas?

quite often it's the pickup sensor that goes bad requiring a new harness.which includes the sensor.

david, you wouldnt happen to have a part number for the sensor/harness, I wasn't able to find one in the EPC

it is a 126-540-46-13 hope this helps.

thanks, hmm they dont give a number for the pickup sensor weird

alright, so we finally picked up the car from the shop. $1150, new chain, both ball joints, fuel lines, fuel pump mounts, tie rods.

They said that something is wrong in the transmission, they said the sensor works fine. Does anyone have any idea whats might be up in the transmission?

I have two 722 manuals but I cant find anything that points to the speedo pickup...

I know the sensor is hall effect so somewhere theres a shaft with something on for the sensor to pick up...

if the sensor is good that means that someone had the trans apart and didn't put the pcs back on the shaft in the correct order.this problem can be corrected by taking off the tailshaft housing and correcting the mistake.

david, do you have any info on this procedure? diagrams? pictures? how difficult is this task?

it is not difficult.remove crossmember,flex disc and let trans hang down.you will need 27mm deep socket to remove nut holding flange on rear shaft.there are about 7or8 13mm head bolts holding the tail shaft housing on to trans [of varying lengths].you will have to take out the parking pawl so take pictures or notes.be careful of the gasket where the housing joins to the trans body.look at how the various components are lined up on shaft and it should be obvious what is in the wrong place.the speedo will be a wheel with segments on it that is supposed to line up with hole where the sensor fits. NOW this could only have happened if the trans was taken apart so be very sure that the sensor is working before going to this much trouble.

david,

I found this diagram, which part is the speedo wheel?

http://imgur.com/5gG4ul.jpg

Hmmmm

Also found this mentioning electronic speedo:

http://imgur.com/O7O8ul.jpg

it appears that you answered your own question with second set of pics.

So the sensor picks up on the parking lock gear? or the rotor atop the gear? Hm, I would think if the rotor was gear was installed wrong you wouldnt have park?

FIXED.

X49/2 Connector. On driver side of center console by accel pedal. Houses a 7 pin connector for reverse lights and speedo. This was somehow pulled apart. Fixed the problem now speedo works, reverse light and cruise.

YAY no need to tear into transmission!

David, thanks for all your help. I am very glad to say that we didn't need to dive into it though :)