Crankshaft position sensor

Folks,
Anyone know a definitive way to test the crankshaft position sensor<
Also , who is likely to have the best prices for the sensor .
I have a 2000 540I6 and a 1997 840Ci. I just had the 840 refuse to start and my troubleshooting is pointing at the CPS, but the problem has not been recorded by the DME according to the Peake code reader.
Anyone have a similiar experience ?
Mike

according to Bentley, your car will not start with the CPS Malfunctioning and the ECM should throw a code if it does not receive any signal from the CPS

Originally Posted by Mike's 5040I

my troubleshooting is pointing at the CPS

From the BMW E39 glossary (1) ...

Originally Posted by Ryan M

Although it is accepted on this board that "CPS" means camshaft or crankshaft position sensors, that's actually incorrect. CKP is the correct acronym for crankshaft position sensor and CMP is correct for camshaft position sensor. Just some FYI.

Unfortunately, there's not much about testing the CKP in the VERY best of E39 Links.

Here's all I found:
- HOW TO REPLACE THE CRANKSHAFT POSITION SENSOR ON A BMW 2002 530i e39

To the OP:
Since every thread is supposed to further our tribal knowledge, when you do solve this problem, please either write it up or tell us where you found the best references ... so that we can augment the VERY best of E39 Links for the next person to stand on your shoulders.

All CPS's (crank or cam :-) ) should be OEM and nothing else. You may find them cheaper on ebay and the like, but you will probably be replacing it again within a month.

Originally Posted by Quackers

All CPS's (crank or cam :-) ) should be OEM and nothing else. You may find them cheaper on ebay and the like, but you will probably be replacing it again within a month.

I can relate to this. Get the OEM BMW brand. Even the BavAuto generic brand will fail in a matter of weeks.

Thanks to all of you that replied.
The electrical diagrams seem to indicate that it is a passive variable - reluctance pick up , not a hall - effect sensor , so it should have a measureable coil resistance . I'll send my measurements back to the forum.
Thanks!
Mike

I did both cam and crank.. very easy to do...

Cam was about $130 and crank was $80

Yes, you can test this sensor. You will need a graphing type meter. I use a Snap On Vantage meter.

At the sensor connector (underneath the car near the bell housing), backprobe the connector. You should have a two wire connector. CKP + is yellow, CKP - is black.

KOEC (key on, engine cranking) should produce a sort of sine wave pattern.

KOER (key on, engine running), should generate an AC voltage from 11 to 17 volts. As RPM increases, so should voltage. (If the car is not running, then this test would be tough to do.....)

As you noted, you can do a resistance test. Should be about 500-600 ohms between the terminals identified above.

Originally Posted by mtnbimmer

Yes, you can test this sensor

So that every thread builds upon the diagnostic misfire thread, I added this to the classic tests:

- How to diagnose a BMW E39 engine misfire (1)

Test the CMP (aka CPS) camshaft position sensor (1) (2)

• The CMP will set a fault when it is bad (per bimmertec)
• If bad, replace the CMP

I just learned how to test a CPS from an engineer I know that works for Bosch. With it removed, attach leads from a multimeter to the positive and negative terminals on the plug. The third terminal is the signal. You should get a reading around 500 to 600 ohms. Take a heat gun and begin to heat the CPS up. The ohms will go to 700 to 900 but not continue to climb on a good one whereas a bad one will continue to climb till it reaches a point where it goes offline, meaning open circuit.

Originally Posted by TemporarySanity

I just learned how to test a CPS from an engineer I know that works for Bosch. With it removed, attach leads from a multimeter to the positive and negative terminals on the plug. The third terminal is the signal. You should get a reading around 500 to 600 ohms. Take a heat gun and begin to heat the CPS up. The ohms will go to 700 to 900 but not continue to climb on a good one whereas a bad one will continue to climb till it reaches a point where it goes offline, meaning open circuit.

Cool!

mw

Originally Posted by TemporarySanity

I just learned how to test a CPS

I'd like to add this to the diagnostic misfire thread ... but before I do that ... can you confirm whether you're talking about the CMP (camshaft position sensor) or the CKP (crankshaft position sensor) when you say CPS?

TIA

Hi Blue Bee ,
I am having the problem with the Crankshaft position sensor . The power supply on the fuel pump fuse is not set to +12 V, so the process is to see if the crankshaft position sensor is operating , as a non - functioning sensor inhibits the fuel pump relay. The supply should be applied for 3 seconds when cranking is initiated , but the DME looks for crankshaft pulses or it releases the fuel pump relay. Apparently , the DME does not want the engine operable if the Crankshaft position sensor is inoperable.
I have a DMM and an oscilloscope , so when I get the time to fully diagnose I will send in pictures and measurements for my fellow E39 brethren.
Mike

Originally Posted by Mike's 5040I

Thanks to all of you that replied.
The electrical diagrams seem to indicate that it is a passive variable - reluctance pick up , not a hall - effect sensor , so it should have a measureable coil resistance . I'll send my measurements back to the forum.
Thanks!
Mike

WDS says that the crank position sensor is a hall effect device.

*****************
Crankshaft Sensor

The current engine speed is transferred via the crankshaft position/rpm sensor to the engine control unit. The crankshaft position/rpm sensor is designed as a Hall-effect sensor. An incremental wheel indicates the current crankshaft position. The crankshaft position/rpm sensor sends out a square-wave signal as the engine turns over.

Steps taken by engine control unit in the event of a fault in the crankshaft position/rpm sensor.

If the crankshaft position/rpm sensor is faulty, a corresponding fault code "crankshaft position/rpm sensor" is stored in the fault code memory of the engine control unit. The camshaft sensor signal is then used as the engine speed signal (emergency operation).

Possible effect: Misfiring is possible and start characteristics deteriorate.
*****************

EDIT: I should have noted this is in the MS43 section. MW7.2 and MSS62 say the same thing
EDIT2: Cam position sensors are hall effect also.

Regards
RDL

I'm sorry, I was referring to the crankshaft sensor. I believe the same technique would work on a cam sensor but the ohms may be different.

The less post count they have, the more acronyms they use.

I can understand why. It's interesting though.

mw

To always improve our diagnostic procedures with value extracted from every thread, I added the crankshaft position sensor information to the misfire diagnostic DIY:
- How to diagnose a BMW E39 engine misfire (1)

Should I stick with whole words so not to confuse the masses and to be more precise? I do realize there are people here that don't know what all the abbreviations refer to, but when I'm posting, I know what I mean and tend to forget that there are so many similar ones. No harm though.