VDO Speedo in '92 Breakaway

Speedo read 10% over GPS (actual )speed. Decided to calibrate to read accurately.
Removal simple. Make sure to identify wiring connections. My 4 speedo wires individually plugged into wires that were all the same color (white) so identification is essential. Unscrew bracket thumbnuts to remove speedo outwardly from face of dash.

To access the calibration one needs to separate the speedometer. To do so the bezel retaining ring needs to be removed by lightly prying the back edge of the ring. And once the wires retainer is released the guts can be lifted from the housing.

Reference:
http://www.mwrench.com/barth/S...DO%20speedometer.pdf

and

http://www.mwrench.com/barth/S...metercalibration.pdf



Ed reduced his gauge speed reading by increasing the pulse range. I did the same - decreased my gauge reading by increasing the pulse range.

Again, my gauge read 10% high. Using my original 10 position settings I determined my original pulse range. I mathematically increased that original pulse range by 10% and located that higher range on the chart, then set the 10 positions accordingly.

Winterized so Spring will reveal if I did this correctly.

Incidentally, my 13.2 average mpg (thought) has been reduced 10% - 12 still isn't bad. And the actual total mileage on the coach is 3982 less.