how to test a crank position sensor

[MW2469]

does anyone out there know of a way to test a crank position sensor to see if its sending a signal? please see my question under CUSTOM BIKES... "custom bike no start" for the reasons I need to find this out-I'm stumped-anyone out there with ign knowlage willing to take a stab at my problem?[sm=headbang.gif][sm=feedback.gif]

[wlbowers]

Put an oscilloscope on the sensor leads and spin the engine. You should see a pulse coming from the sensor.

[MW2469]

Thanks for the reply.what do I do if I can't lay my hands on a o'scope? Any other options?

[piniongear]

I have sent you an email about getting the Position Crank Sensor procedure to you. If you respond to that I will be glad to forward it to you................piniongear

[wlbowers]

ORIGINAL: MW2469

Thanks for the reply.what do I do if I can't lay my hands on a o'scope? Any other options?

The CKP sensor has a B+ power supply, a ground, and a signal circuit.

As the crankshaft rotates, the wheel teeth interrupt a magnetic field produced by a magnet within the sensor. The sensor's internal circuitry detects this and produces a signal which the ECM reads. The ECM uses this signal to accurately measure crankshaft velocity which is a variable used in order to detect misfire, spark and, fueling.

Looking at your service manual find the wire that goes to the B+ Measure from this wire to ground for the DC supply voltage. Measurement should be taken on the sensor side of the connector. Ground connection as well.

On my Dyna this wire is marked BK for Black. Do this test at rest and with the engine spinning. A loose connection could break as the motor shakes.

If you have voltage present with the key on and with the engine spinning move the positive meter lead to the Signal wire. This is marked R for Red on my Dyna. With the engine spinning you should see a voltage signal on that wire.

You should measure the signal at the sensor connector and the ecm to verify it is reaching the brain.

Good Luck

[FXDWG2002]

Originally Posted by piniongear

I have sent you an email about getting the Position Crank Sensor procedure to you. If you respond to that I will be glad to forward it to you................piniongear

Piniongear, I hope you still monitor this thread. Would you mind sending me that Crank Position Sensor procedure to me?

fxdwg2002 at verizon dot net

[rbabos]

Is there no across the terminal resistance check that will varify it's condition, like ignition coils?
Ron

[Old Gunny]

And the crank has a skipped tooth so the ECM knows where TDC is.

Most of these sensors work by majec, sometime the spell wares off.

[FXDWG2002]

For those of you that don't know, 0v-5v is TTL logic used in 100% of digital circuitry. This is digital because the red wire and black wire are independent of any power source or ground on the bike.

Ok, I do not have an o'scope to test this with. But it is my understanding that the magnet in the CKP sensor will produce a 5v pulse every time the missing teeth come around. This can be seen on a multimeter as a change from zero (actually 2.81v) to 5v. Do I understand correctly?

It takes 2.81v just for the ECM to register the presence of the CKP sensor.

I kept the plug hooked up between the CKP and the ECM. I pushed straight pins into the connector so I could see the operation (or lack there of) in circuit.

[rbabos]

Originally Posted by FXDWG2002

For those of you that don't know, 0v-5v is TTL logic used in 100% of digital circuitry. This is digital because the red wire and black wire are independent of any power source or ground on the bike.

Ok, I do not have an o'scope to test this with. But it is my understanding that the magnet in the CKP sensor will produce a 5v pulse every time the missing teeth come around. This can be seen on a multimeter as a change from zero (actually 2.81v) to 5v. Do I understand correctly?

It takes 2.81v just for the ECM to register the presence of the CKP sensor.

I kept the plug hooked up between the CKP and the ECM. I pushed straight pins into the connector so I could see the operation (or lack there of) in circuit.

Sounds good to me.
Ron