Help ! VSS and EST Monitor error

[Axel-F]

Dear all,

I am submitting this request for a friend M100 driver, we need your help !

After usualy around 20mn driving, when releasing the accelerator, check engine light turn on, and engine rev is limited to 3 800 rpm.
Need to stop and restart the engine to exit safe mode (rev limited to 3 800rpm).

An elanscan has been ran, and show 2 faults codes :
- VSS : and as a mater of fact, the scan didn't record any speed during recording (despite very fast drive !)
- EST Monitor error.

Here is the scan :

M100 Gerarld.zip

What is surprising is that VSS has just been changed ( same for MAP)...

Any help is welcomed !!

[Giniw]

Hello,
Have you searched in the engine management manual? There are usually the voltage one is expected to measure on the sensors.

[Axel-F]

Hello,
Have you searched in the engine management manual? There are usually the voltage one is expected to measure on the sensors.

You mean checking voltage to ensure VSS is not damaged ? Shouldn't be easy, cause need to do it while driving... isn't it ?

VSS.png

[Giniw]

That is not easy indeed ... Maybe on a bridge?
But with a square wave signal it will not be easy anyway ... unless you have an oscilloscope
---
What is the lower code of the VSS and EST? The workshop manual tells to address the lower code first when multiple error codes are reported.

[Simon_P]

EMK4 - 42 tells you how to test the VSS.

[Axel-F]

EMK4 - 42 tells you how to test the VSS.

Yes thanks ! 42 is for EST, VSS is 24, but it should help to do some testing !

[Fredjohn]

EMK4 - 42 tells you how to test the VSS.

Yes thanks ! 42 is for EST, VSS is 24, but it should help to do some testing !

I think you may have misunderstood Simon's comment.

He is suggesting you look at the Workshop Engine Management Manual and read section EMK4 Page 42 (and 43). These pages tell you how to diagnose and test.

Similarly EST code 42 information is shown in Section EMK4 Page 52 and 53 in the same manual.

Hope this helps.

[Simon_P]

Sorry - Not clearly explained - Thanks Fred

Axel,

EMK4 page 42 describes how to test the VSS with the wheels in the air and the engine switched off.

Before doing anything check the base timing and set the idle - These are reference points if you haven't checked them you are guessing.

i did look at your scan but the EST and VSS flags were set before you started the scan.

[Axel-F]

Sorry - Not clearly explained - Thanks Fred

Axel,

EMK4 page 42 describes how to test the VSS with the wheels in the air and the engine switched off.

Before doing anything check the base timing and set the idle - These are reference points if you haven't checked them you are guessing.

i did look at your scan but the EST and VSS flags were set before you started the scan.

Ok, understand, EMK4 code 24 is page 42, we are aligned !
Thanks !

[GeoffSmith]

No speed output at all indicates a VSS signal is not getting to the ECU. I would do as the manual says (but in the reverse order ) and check the output of the VSS then the input to the ECU.

PS Why was the VSS replaced Axel?

[Axel-F]

...
PS Why was the VSS replaced Axel?

To try to solve the fault code 24 "VSS"... but it didn't work !

[GeoffSmith]

That's what I suspected hence the suggestion to make sure it is working then following the signal through to the ECU.

Can you confirm that the CEL lights (as it is on a common supply to the VSS)?

[Axel-F]

'...
Can you confirm that the CEL lights (as it is on a common supply to the VSS)?

From what I understand :
- fault code 24 (flag 0) and 42 (flag 8 ) are read "on" by elanscan
- elanscan does not read any speed, despite car is obviously driving (fast)
- CEL does only lights from time to time, usually after several minutes driving, and when releasing the accelerator, then the engine is in safe mode ( turning off the engine reset the safe mode)

From the scan provided above, fault code 24 & 42 are on, but CEL didn't lights ( this time...)

[GeoffSmith]

Axel, the reason I asked if the CEL was lighting was because the CEL light is shown with the same supply as the VSS.

http://wikilec.9600.org/images/1/1e/MJ2 ... rbo%29.gif

Note: Ignore the above as I've just realised that the supply is common throughout the instrument panel.

http://wikilec.9600.org/images/9/99/MJ2 ... uments.gif