Testing Slow Cranking Speed Prob
Testing Slow Cranking Speed Problems
Evaluating Grounds and Battery Wiring
Quality of your vehicle main wiring, as well as cranking problems, can be isolated through
a few quick, simple, measurements. All that is needed is a simple inexpensive digital volt
meter, a clip lead or two to attach the probes, and someone to crank the car
while you read voltages. With a few basic readings, you can use an Excel sheet I
made to evaluate both grounding and battery wiring.
Ignore any negative sign and just record the absolute voltage. Use the lowest
meter scale possible. Use a clip lead if necessary to assist you in holding a
connection. In my car, the starter current is over 350 amperes on initial hit.
The start current quickly drops to about 175 amperes after the engine starts
spinning. Record the steady voltage as it spins, not the initial hit.
Measured While Cranking (unless
Voltage from the probe
placed on physical center point on battery
negative post to vehicle chassis on the opposite side of vehicle is ____________ volts. This
measures battery grounding. Lower is better, should be less than 0.5 volts.
Voltage from the physical center
point on battery positive post to chassis opposite side of vehicle is
______ volts. This measures battery charge (no crank should be over 12.5 volts
at full charge)
and cranking supply voltage (should be over 10.2 volts with a good battery).
Voltage from the engine block or manifold to vehicle
chassis away from, and forward of, any engine ground points is ____________ volts.
measures block grounding, and should be less than 0.5 volts.
Voltage from the starter solenoid battery terminal post
terminal stud to the vehicle chassis is ____________ volts. This is voltage available for
starter at relay, and should be over 10.5 volts for best starting.
- Voltage from the starter positive post stud to bell housing or block is
____________ volts. This measures actual starter voltage, and should be over 10
Note: Download the Excel page, and edit only the Green areas!!
My car results using Excel sheet are shown. You can see my wiring results.
Download Excel sheet CLICK HERE
|B- to chassis||B+ to chassis (no crk)||B+ to chassis crnkg||Block to chassis||Start Sol + to chas||Starter to block|
|Battery loaded||11.45||good bat|
|Battery Lead drop||0.27||good|
|Solenoid to starter||0.06||good|
Note: If multiple results are bad, starter could be drawing excessive
current. Normal start current is less than 200 amperes. This requires a
special test meter.
Please give me feedback using this test. Type this in: