1995 GMC Jimmy SLT 4.3 L Vortek

When I apply the brakes at a stop light or other, the Battery Voltage as monitored at cig lighter or Voltmeter on dash drops from 12.74 volts to 11.65 volts.

Quite a few weeks ago I remember re-organizing my EVAP Emission hoses
and connecting / disconnecting the Window Washer pumps.
Window Washer pump is currently un-connected.
After doing this re-organization of EVAP / EMission hoses the Brakes would not
cause the Battery voltage to drop while applied.

It appears either of these two items was cause of Brake Booster creating this
drop in Battery Voltage when brakes are applied. When Brakes are released
then Battery Voltage returns to normal.

IS THIS NORMAL ? ? ?
Thanks for any help.

 

The brake booster runs on vacuum from the manifold and nothing electrical. There is no way the booster was causing the drop in voltage. The brake lights could be doing it, the ABS module possibly but I doubt either being as you aren't having the problem any more.

Hook up the wipers and see if you are still having the problem.