W124 Speedometer Problem
 

I recently had to pull the gauge cluster to change the N2/4 relay in the dash on my 1995 E300 Diesel and ever since the speedometer hasn't worked right. The speedo cable was very tight and I had to pull very hard to get enough room to detach it from the back of the cluster so I was afraid I broke it internally. The speedo would stick and randomly jump to speeds slower than I was actually going but today it stopped moving at all. I was prepared to replace the cable but noticed that the odometer still works. Through my searches I could only find the opposite happening and it now has me wondering if the cable is truly at fault. If anyone could help I would greatly appreciate it. The car has over 275,000 miles, so the cable was probably due for replacement anyway, but I just want to make sure that is the issue. Thanks

The speedo head is mechanical, so if the odometer is working, your cable is functioning. When you have a tight cable, it is wise to disengage it from the transmission before pulling the IP and damaging the cable/speedo head.

Question:

You say the odometer works. Is it accurate or recording less than the true miles driven?

Jim

I did disengage the cable from the trans to reinstall the gauges as I couldn't get it to thread onto the speedo without some extra slack, but in hindsight I should have realized the problem earlier. The odometer did seem to be working normally but I'll have to check it to make sure if it really was as accurate as it looked. It's starting to sound like I damaged some gears inside the speedo itself.

When I pull my cluster on my E300D I can free a bit of cable just beneath the emergency brake pedal. It's not much but enough. This is on a RHD and may be different on LHD.

I've got a different problem with my speedo which I'll have a look at soon. It jumps around between 40-60.

Ok, so I let the car sit for a few days and just now when I drove around a bit the speedo worked normally up until around 40mph. Once I got above 40 it would stick somewhere and not go back down until I dropped to below the speed it was stuck at. I got one or two jumps from the needle below 40 when accelerating but the needle always fell smoothly. The odometer is still working properly. I now believe the cable is fine but some of the speedo internals must have some sort of problem. Does anyone know what the inside of the gauge looks like or what the problem might be?

I pulled the cable out of the little clip in the footwell and that gave me a little, but underneath someone had zip tied the cable to a ground strap which restricted its movement and gave less slack.

This will give you a general idea of what is involved.

How to Repair Your Broken Odometer

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