Speedo Error Correction & ABS Safety Issues?

[noelb]

The VSS (Vehicle speed sensor) on my Burb is giving a reading about 3mph different to the speedo. I believe, but have not tried as yet, that I can reprogram the PCM via my OBD II interface to correct the speedo. The VSS will then think the vehicle is going 3 mph slower actual speed -- What safety issues will this cause with the ABS? Any thoughts?

[More Power]

Could be the VSSB was altered. Is it possible to alter the speedo calibration using your OBD II interface? I can't imagine a safety issue if both speeds agree.

Jim

[noelb]

Jim, YES it is possible to correct for changes to tyre size and final drive changes - you just calculate the percentage change and follow the procedure and it should work. (It may depend on what type of VSSB you have and whether it contains the jumpers)

I haven't tried it on my burb yet because I know that the PCM needs to know the actual speed of the vehicle and I suspect by adjusting I will change both values on the VSSB and the Speedo. The VSSB will then be registering a speed lower than actual by about 5%.

I am not sure of the safety issues that may occur particularly with the ABS.

I hope someone can provide someone can provide some advice.