APP Ohms Law

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Automotive Applications > Application Note 5. > Diagnosing Fuel Pressure

Automotive Applications

Diagnosing Fuel Pressure on GM Vehicles

Example of Ohm's Law

If you measure 0.5V across a ground connection in a starter circuit, and the starter draws 100 amps, calculate the resistance as follows:

Ohm's Law E = I x R
0.5V = 100A x R
Solve for R
0.5V
R=100A
Therefore R = .005 Ohm

.005 ohm is too much, so clean the connection. .5 Volts tells you the same thing—the connection is dirty or corroded.