When you need to measure the voltage on the Ultimate MPU Board you have some very useful test points that make this very easy to accomplish. TP1 (5v IN) is for the red lead, positive voltage. TP3 (Gnd) is for the black lead or ground. Notice in the picture below not to use the ground strap for the black lead. The reason for this is if your ground is bad on your MPU connector you won't catch it if you use the ground strap. Any 5v reading of 4.85vdc or less is something that needs to be repaired.One other thing to check while you are doing this test is to check your AC voltage leakage.  What can happen on the old original Solenoid Driver boards is the main capacitor or the regulator can go bad.  Keeping the leads of your voltmeter on the same test points that you just measured, switch your meter to AC mode.  If that voltage is over 100mv AC then consider replacing the Solenoid Driver board