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Discussion Starter · #1 ·
I've decided to start diagnosing my lagging speedo. Last summer, I replaced the rear left speed sensor but it didn't solve my lagging speedo. (it indicate about 80kph when I drive anywhere between 70 and 110kph or so...)

On the wheel speed sensor page of INPA, the speed value for each wheel is set at a maximum of 20kph by default. I've looked and I can't seem to find where I could edit this value to increase it to 100 or 120 so I can test at higher speed.

At the moment as soon as I go past 20, the software crashes and stop...

Hints?
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I've decided to start diagnosing my lagging speedo. Last summer, I replaced the rear left speed sensor but it didn't solve my lagging speedo.
Do you have all the ABS and DSC lights on? If they are fine then likely all your sensors are fine. Does your cruise control work and maintain proper speed?
Edit:
I just happened to have to do a test on another car so lets save some time. I was working on something else and have to check things as I go but did not check the secret menu test #. On this car it is 2 and IIRC it is 2 on an E39 but find the secret menu thread in the FAQ thread which is a sticky and get the details.
Open the secret menu and go to test 2, this tests the cluster all the lights and the gauges. The tach and the speedo sweep at the exact same speed and go to max from zero and back in a controlled manner.
If they don't then it is probably your cluster,(these can be fixed by a board member) there are some other tests in the secret menu like ground speed that can help but lets start here.
 

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Discussion Starter · #3 ·
No the ABS and DSC are off, car works normally, appart from the speedo who doesn't closely follow the actual speed of the car. From what I could test yesterday, from 0 to 20kph all four sensor read fine with no fluttering or loss of signal.

I'll check opn the secret menu and do a cluster test as you suggested.
 

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Discussion Starter · #4 ·
Just tested the function and both needles are in sync. No hesitation or weird stuff.
 

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Just tested the function and both needles are in sync.
If there was any flaw in the speed signal going to the DME then there would be an ABS or DSC error and your first failure would be cruise control of the creature comforts if it was anything other than the cluster or coms.
Go to the secret menu thread and find the road speed test and check that is working different than the speedo. Sorry my memory is failing but I have read this complaint before, just don't remember what the exact answer is. Pretty sure it is a bus error or straight cluster error. This guy has a service to repair clusters and has a standup rep here so lets tag him and see if he can likely fix it,
@blackknight530i
 

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Discussion Starter · #6 · (Edited)
To go back to my initial question, can we adjust the 20kph value in INPA graphic to 100 ? That would help identify if my sensors start acting up or diverging only at higher speed, which seems to be what's happening.
 

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To go back to my initial question, can we adjust the 20kph value in INPA graphic to 100 ?
The reason I jumped in was because of that question. I doubt INPA can do it, I suspect you would have to use a sister program. That said if you have to ask you may not know all the other questions or answers before you start changing values with a program. The number of posts that I have read that start with and end with, I just changed .... and now the car is broken. Do you know what that 20 value represents? If you are guessing at the answer or assuming something, you should not touch it.
 
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