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Old 10th January 2015
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Default Crank Position Sensor Testing

Introduction/Basics/Other CKP applications
Many crank position sensors (CKP) are 3 wire hall effect sensors, such as used on a Dyna or my Jeep Wrangler TJ. Middle lead is ground, one outside lead is power and the other is the 0-5 VDC signal.

This type is best checked with an oscilloscope or a quality multimeter which measures root mean square (RMS). It can, however, be tested with a basic multimeter in the low voltage DC range: If functional, if a good ground and if adequate voltage to the power lead, it will produce the following approximate (~) voltages:

While cranking: ~0.5 VDC
At idle: ~0.3 VDC
Static (key on, bumping starter until a close signal is received): 5 VDC

The signal is 0-5 VDC square wave, thus the average voltage read is rather low.

When a vehicle is not starting, this basic test will validate a functional CKP. A failed unit (or poor connections) will not provide a 5 VDC square wave (digital) signal. However, this is not sufficient to test for a failing unit with inconsistent output. An oscilloscope, while cranking or motor running, should show the hiccup of a failing unit.

Sportster CKP
Sportster crank position sensors are 2 wire units, which may be described as variable reluctance sensors or magnetic pulse generators, etc. They do not have as clean a signal as hall effect, but generally more durable (simple coil). As with the hall effect, they are typically rated -40 C to 150 C (300F). It would be interesting to use a temperature gun aimed at the CKP area after a hard ride in hot weather.

For 2004-2006 Sportsters, the red lead is connected to ICM position 8 and the black lead to ICM position 9.

For 2007-2013 Sportsters, the read lead is connected to ECM position 30 and the black lead to ECM position 12.

Output is measured by probing the two connections, while cranking.

Insulation piercing probes may be used, or just probe the ICM or ECM connector at the correct positions. The black and red leads are twisted pairs.

The above is basic info from 2004-2006, 2007-2009 and 2010-2013 schematics.

Following is from research without opportunity to test on a Sportster. Any Forum member with actual voltage reads is invited to provide multimeter readings.

While cranking: ~ 0.3 VAC (note this is a sine wave and requires the AC scale)
At idle: ~ 1 VAC
Static: N/A

When your bike is not starting, this basic test will validate a functional CKP or indicate a failed CKP. A failed unit will not provide a signal. However, this is not sufficient to test for a failing unit with inconsistent output.

Although CKP issues are common, maybe the above info will save some unnecessary replacements.

Last edited by sportsterdoc; 10th January 2015 at 22:37..
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