FG MK2 Vehicle Speed Source can not be altered.

[Mick]

Hi

I have been chasing the ability to adjust the displayed speedo reading in FG Mk2 ZF for a long time and have got nowhere and it has been said that the reading most likely comes from the ABS module, so it may not be adjustable using any tuning software.
I decided my next best option was to adjust my trans data if possible, so that the vehicle speed reading was accurate in any datalog that I do, and I live with the speedo inaccuracy.

Today I came noticed that when logging the car, that the Vehicle Speed Source (VSPEED SRC) displays the source as ABS via CAN, even though I have changed this is several places and I have the VID Block disabled.

This is displayed when logging the ECU only, so it is not the trans displaying it.

This does confirm that the signal is coming from the ABS module, but as it’s in the ECU, why can’t it be changed?

I’m sure if it was accessible to be changed, then I could adjust things as I have been trying to do

My strategy is HAER1UB but I have never been able to adjust the speedo over various FG MK2 strategies, there was no problem adjusting them on the previous models.

 

Should I have the ability to be able to change this source?

 

I have sent a ticket but thought I'd see if anyone here has come across this and may be able to shed some light on the issue

 

 

[Roland@pcmtec]

This comes from the cluster in the CCC block in the cluster, it may be relayed from the ABS module but the source of truth is the cluster.

To trim your speed you would need to decode the CCC block the cluster. If you have a paid forscan edition read the AB data from the cluster on two different vehicles (with different wheel sizes or sources) and post the binary data here. This is not documented anywhere but we may be able to decode it (or break your cluster, unlikely but a risk you need to be willing to take).

[Mick]

Thanks Roll's
I can't get Forscan to read my cluster and have tried 3 different dongles.

My question was more about that there is a choice of "VSS_Source  Speed Control Source" in the VID block section and also there is "auF16589  Vehicle Speed Source when VID BLock is not selected" in the system switches, these appear to be in the ECU but have no affect to be able to change the actual VSS that is in control.

I understand that the speed signal appears to come from possibly the ABS module, but I guess maybe a better question would have been, are these disabled somewhere and can it be overwritten? or is the software not able to implement the change?