so i have just ran a 12v line with 15amp fuse straight from my battery to the microtech to the Batt line on the plug in connector.

... i have 14.15 volts at the cable with the car running.
the microtech only displays 13.70 to 13.80 volts on the hand held display or with the laptop connected.

is there any reason for this ???? common problem? where are my volts going ???

 

ground offset issue.. pay attention to the factory diagram for the earths.. no shortcuts

 

sighs..

...ground offset calibration error ....ground loop .. earth potential....

this is what happens when you force multiple or insufficient paths to ground all with different resistance paths

you need to check the B+ and earth wires for pinch or bad connection .. and be sure the earths are placed as directed by microtech themselves

.. so many times this is caused by lazy install straight off the alt and then earthed just to engine block

there is two earth wires on a microtech,,, one in the ignition bundle and goes to engine block
-this is engine earth-


the other. the thick one . goes back to the battery .. this is ground ..
NOTE...this is not the engine block ..



the micro should also be fed B+ directly from the battery ..

fail to do any and all of these things and you will get funny results for lots of things and not just in the voltage reading

NB
the chassis ground point at the end of the battery strap is acceptable as the full ground for both wires if all the earths tie at this one spot ( include engine strap )