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Old 09-25-2013, 10:21 AM   #1
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Crank position sensor testing 93 4.0

Howdy! My 93 Wrangler with 4.0 and five speed manual shut down while backing up and has not run since. I checked connections, swapped relays, and the ignition coil. I have no spark from the coil. The coil tests out with the ohm meter. I need some guidance on testing the crank position sensor. (I found a tutorial posted in 2011 by 2000 XJ Cherokee on another forum for which I am grateful.The image below came from his post.)

I have a Fluke 175 with a fresh battery. The red lead is plugged into the red socket marked for ohms. The black lead goes to the black socket marked COM. I tested by the diagram below. When I put the red lead of my multimeter on C and the black lead on B, I get OL for overload which I take for infinity. Reversing the leads takes a reading of 440 something or other. I read that any reading other than infinity (in this case OL) finds a bad CPS, but I am too ignorant to know if the placement of the leads matters. Does it?


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Old 09-25-2013, 01:03 PM   #2
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picked up a new one. tested the same as the old one. thanks.

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Old 09-25-2013, 06:19 PM   #3
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OL measns Out of Limit, change the scale on your meter.

Better yet, get a scope, test it while cranking, should look like this (this is dual trace matching cam (cam @ Distrubitor) to crank):


Ref:http://www.justanswer.com/jeep/2obfz...park-coil.html

^ you might fond some good information in that link ^
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'93 Black YJ, 4.0L AX15 - UNDER CONSTRUCTION!
http://www.wranglerforum.com/f330/2x...ad-490865.html
'04 SV1000s:
http://www.svrider.com/forum/showthread.php?t=280873
Old Jeep that was totaled (and SOLD!):
http://www.wranglerforum.com/f330/2x...ad-101879.html
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Old 09-27-2013, 10:41 AM   #4
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I get OL on all settings using manual or auto scaling. Since then I tried it with an analog that has only a dial. Same deal.
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Old 09-27-2013, 12:12 PM   #5
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Quote:
Originally Posted by howl View Post
I get OL on all settings using manual or auto scaling. Since then I tried it with an analog that has only a dial. Same deal.
Yes, you ar still out of limit, probably an open circuit.

Key on, with the engine off, you should have 5V on the engine side between 2 and 3 (power supply). Once you have verified you are getting power as needed the rest is all about verifying signal, and part integrity.
Oh and make sure the signal wire is ok, this normally is not the case, but on a 20~ year old vehicle anything is possible.

Here is a GREAT article explaining the sensor and how it works, I would skip to the 3 wire sensor part.

Part 1 -Crank and Cam Sensor Diagnostic Basics
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'93 Black YJ, 4.0L AX15 - UNDER CONSTRUCTION!
http://www.wranglerforum.com/f330/2x...ad-490865.html
'04 SV1000s:
http://www.svrider.com/forum/showthread.php?t=280873
Old Jeep that was totaled (and SOLD!):
http://www.wranglerforum.com/f330/2x...ad-101879.html
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Old 09-27-2013, 05:38 PM   #6
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Got if fixed! Thanks!
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Old 09-27-2013, 06:27 PM   #7
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Got if fixed! Thanks!
What did you end up having to replace/repair?
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'93 Black YJ, 4.0L AX15 - UNDER CONSTRUCTION!
http://www.wranglerforum.com/f330/2x...ad-490865.html
'04 SV1000s:
http://www.svrider.com/forum/showthread.php?t=280873
Old Jeep that was totaled (and SOLD!):
http://www.wranglerforum.com/f330/2x...ad-101879.html
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Old 11-16-2013, 08:57 PM   #8
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The main thing was the coil. The cap, button and coil wire looked rough, so I replaced those too. I did not realize is had been running so rough until afterward. Thanks again!

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