New guy w/ quick question

[nedc]

Hi- I have mated a 2010 SH150i drivetrain w/ a 2011 Honda PCX...don't ask me why, but it seemed like a good idea at the time. Anyway, having bought the SH150 as a stand alone drivetrain with no prior knowledge of if it ran or not, I can't get it started. It has good compression, spins over quickly and fuel pump primes, but no spark. I am thinking the Crank Position Sensor is the culprit. So...my question is- should the two wires coming out of the CKP have continuity? I think they should and mine doesn't. I get real erractic voltage readings on the sensor when spinning the engine. Thanks for any help.

[TommyXP]

My bet would be that you should measure continuity through the CKP wires, as it is only but an inductive iron core 'coil' according to the wiring schematic......
If the weather wasn't so brutish at the time, I'd measure mine to be sure for you....
Good Luck.

[waspmike]

Could be Hall Effect in which case simple resistance testing won't work.

[nedc]

i think it is hall effect. If someone with a running motor could tell me if there is continuity present or not that would simplify my troubleshooting process.

[robber57]

From the service manual,

CRANKSHAFT POSITION (CKP) SENSOR PEAK VOLTAGE
Check all system connections before this inspection.
Poor connected connectors can cause incorrect readings.<<<<<<<<<<<<<<!!!!!!!!!!!!!!!!!!!!!
Remove the luggage box (page 2-5). Turn the ignition switch to OFF.
Disconnect the engine control module (ECM) 32P connector by releasing the lock lever.
Connect the lmrie diagnostic tester or peak voltage adaptor probes to the ECM connector terminals.
TOOLS: lmrie diagnostic tester (model 6251 or with commercially available digital multimeter (impedance 10 MQ/DCV minimum)
CONNECTION: Yellow (+) - White/yellow (-1 Turn the ignition switch to ON and squeeze brake lever fully.
Crank the engine with the starter switch and mea- sure the CKP sensor peak voltage.
PEAK VOLTAGE: 0.7 V minimum If the peak voltage measured at the ECM connector is abnormal, measure the peak voltage at the CKP sensor connector.

Turn the ignition switch to OFF. Disconnect the CKP sensor 3P white connector.
Connect the lmrie diagnostic tester or peak voltage adaptor probes to the CKP sensor side connector terminals.
In the same manner as at the ECM connector, mea- sure the peak voltage and compare it to the voltage measured at the ECM connector.
If the peak voltage measured at the ECM is abnormal and the one measured at the CKP sensor is normal, the wire harness has an open or short circuit, or loose connection.
If both peak voltages are abnormal, check each item in the troubleshooting chart (page 18-4).
See page 12-9 for CKP sensor replacement.
Install the removed parts in the reverse order of removal.
------------------------------------------------------------------

Please observe; the ckp voltage is at 0,7 volt quite low, this means that this pulse signal is susceptable to bad connections,check the voltage at sensor and ecm to make sure you dont have a rotten connector.

To measure the ckp sensor you need either the dedicated imrie tester,an osciloscope, or a regular multimeter with 10 mohms impedance (any decent multimeter will have this) and a so called peak voltage adapter which boils down to a diode/capacitor T at the probe end of the multimeter, a fluke (http://www.amazon.com/Fluke-85RF-II-Fre ... B00937VAW8 )will cost $242 but luckily they provide us with the schematic: https://www.instrumart.com/assets/85RF-II-manual.pdf
You need a little bit of skills in controlling the electrons ,hour sinister evil symbiose, and thats not everyones cookie so heres a link to the tube that will get you started easier and better i can ever explain: http://youtu.be/MmFOPjHqL7Q , making one yourself requires in a basic version 2 /3 parts found in any old radio but you can make it more accurate ending up with the fluke design which requires calibrating with a scope and if you have a scope you dont need a peakvoltage adapter

The fluke is, although a nice instrument, a bit off the scale for measuring a sensor and if you dont want to build something yourself buying on the cheap end is an option, it will cost $80 and upwards which is decent considering the price of the fluke gadget.

Although not a replacement for a real pva you may try the min/max or peak function on your multimeter if it has one,as the cranking speed is low the sinusoid of the ckp sensor will be a low frequency and the max/peak function may capture it to a reasonable accuracy.

[robber57]

After reading more i realised theres a catch; the sensor voltage is so low that a peak voltage adapter may not capture it.
It has to do with the rectifier diode in the pva, this has a voltage drop meaning if you put 1 volt in a diode only 0.3 to 0.8 volt comes out, this drop value depends on the diode type but if you put 0.7 volt in the diode nothing mnay come out so youre measuring 0 volt while the sensor is working well.

Hm.....

I would try the home build variant with a scottky low drop diode And see what this does.

[nedc]

Thanks for your help- I do have the service manual and the testing procedure for the CKP is confusing and I do not have a peak voltage adapter. A simple continuity test will tell me what I need to know and allow me to proceed with my testing. My CKP has NO continuity and I suspect it SHOULD have continuity between the two wires. If I could find out how a known good CKP from a running scoot tests for continuity I will be a happy man and be closer to getting this thing running.Right now, it's looking like a bad CKP or a bad ECM but i don't want to start throwing parts until i know for sure which it is.

[robber57]

I understand your problem, unfortunatly i cannot help you for now as my own broken 2006 sh is in storage and i cannot reach it.

But even so, the pickup is a inductive device and not resistive , measuring the ohm resistance of an inductive device could just lead to measuring a broken device (infinitely high resistance) while in fact the pickup can be perfectly fine.
If you measure ohms the meter is sending a small voltage to the pickup to measure its resitance to this voltage, on a inductive device the device will send a inductive voltage BACK TO THE METER confussing the meter giving a false reading, how "false" this will be depends on the voltage the meter applies to the inductor.
In other words; theres no way to tell the state of an inductive pickup by measuring its ohm resistance, if that would be a possibility honda would have put it in the service manual like they indeed do for other parts.
I am sorry but i cant change the laws of physics for you
There is a fair chance that i will also measure infinitly high resistance at my own pickup.

There should come 0,7 volt out of it when cranking and thats the way to destinct a bad pickup from a good one but you need the pva adapter to measure, in the most simpel form you need to get hold of a (any) germanium or schottky diode and a small capacitor in the region of 20 uFarad , watch the youtube video how to connect and you can measure something usefull.

On just about any other instance of trying to find an electrical error(the dynamo) on a motorbike or car you need this pva adapter so its a tool which you defenitly need if your trying to sort a electrical problem, so imho it is something to look in to as i almost certainly know you will need it more to find your problem.

The measuring itself; just measure the voltaga at the pickup and measure the voltage at the ECM socket to verify you have a good connection between pickup and ecm, both measurements should give 0,7 volt, if the one at the ecm is LOWER it means you have a bad connection between pickup and ecm.

[nedc]

robber57, I appreciate your detailed response. I will try and make one of those devices to measure peak voltage. I used my digital multimeter on ac volts setting and did see voltage when the engine was spinning but it is changing so rapidly (as it is supposed to I guess) it is hard to get any kind of reading. I guess that fact that it seems to be showing some kind of voltage is a good sign. Maybe my ecm is bad...I'll keep looking.