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XJ Rail Sale!The Ruffstuff NOT Universal 4 Link Kit!Vanco Big Brake Kit Promotion!

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Unread 07-17-2013, 10:09 PM   #46
2tall2slow
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Join Date: Jul 2013
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I got a compact dmm from the local radio shack. Probes are wired into meter itself.

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Unread 07-18-2013, 12:35 AM   #47
Uniblurb
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Quote:
Originally Posted by 2tall2slow View Post
I got a compact dmm from the local radio shack. Probes are wired into meter itself.
That will work. In retesting your cranks sensor, and if it turns out to be bad, you'll have to go to the dealer for the OE Mopar replacement. Or you can order a Mopar one online for a less expensive price. Some use Mopar-Wholesale listed below but you'll need to open an account, supply all your info, and use a credit card for purchase. While the Mopar CKP for your 98 4.0 is $48.30 not sure how much shipping is. Don't know if they even supply that info w/o first opening an account.

http://www.mopar-wholesale.com/mopar-parts/catalog.html

Evidently the site won't let you lock in the product in a link so you'll need to search it out.
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96 4.0 ZJ Laredo, 2004 4.7L WJ Limited, 93 4.0 XJ (spare), 96 4.0 XJ (son's)

-Stalling ZJ? 12 things to check before replacing a sensor; the Dirty Dozen
-Crankshaft position sensor multimeter test. & video of testing.
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Unread 07-18-2013, 07:12 AM   #48
2tall2slow
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Good deal. Btw, for future reference, what is a typical resistance reading on a good one?
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Unread 07-18-2013, 08:42 AM   #49
dellis
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Quote:
Originally Posted by 2tall2slow View Post
Good deal. Btw, for future reference, what is a typical resistance reading on a good one?
On a good Crankshaft Position Sensor? It should be "high", above 10,000 ohms.

When you set your meter on the 1K to 10K resistance range, your meter should read "OL" or "1." The OL stands for "Open Loop" and is the reading you should see when the two probes are not touching anything.
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Unread 07-18-2013, 08:56 AM   #50
2tall2slow
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Oh ok. I got the open loop then, when i tested it.
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Unread 07-18-2013, 11:01 AM   #51
Uniblurb
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Quote:
Originally Posted by dellis View Post
On a good Crankshaft Position Sensor? It should be "high", above 10,000 ohms.

When you set your meter on the 1K to 10K resistance range, your meter should read "OL" or "1." The OL stands for "Open Loop" and is the reading you should see when the two probes are not touching anything.
This is where things get a little confusing. Per the last part of the text on the testing diagram posted; "The meter reading should be open (no resistance). Replace sensor if a low resistance is indicated.". So not quite sure how a good crank sensor should "be high, above 10,000 ohms" but maybe you aren't referring to the test?

Believe the wording in the test is a little vague when mentioning to replace the sensor with "low resistance". I tell people to replace the sensor if any resistance at all is indicated since it's supposed to be an open loop between pins B (ground) & C (power). Same thing you just posted about an open loop is the same as the probes not touching anything.

And just to show how imperative it is to not have your probes switched I just tested a brand new Mopar crank sensor for a 93 4.0 XJ not yet installed. I put the red probe on the middle B pin (ground cavity) while placing the black probe on C pin (power). On the 2000 ohm scale the reading was 1860 which is a false reading because the probes are connected to the wrong pins. In placing the black probe on B pin and red probe on the C pin, as they're correctly placed, the reading was "1" which is an open loop, the same as if the probes weren't touching anything, which shows it's a good sensor.

Believe the hall effect crank sensors on these Jeeps, with an internal magnet, has to be one of the most finicky electronic devices they ever created.

Quote:
Originally Posted by 2tall2slow View Post
Oh ok. I got the open loop then, when i tested it.
What does your meter read on the ohm scale when the probes aren't touching anything? And you're saying the reading is exactly the same when having the black probe on the B pin and red probe on the C pin? If so then your crank sensor is testing good.

While somewhat difficult you may want to try moving your wires around on the connector and sensor itself while having the probes/clips attached. Believe I already mentioned testing my CKP on the passenger side which read good and then read bad when moving the connector over to the driver's side for easier access.

I still have that bad crank sensor and with the probes attached correctly it will read "1" as an open loop and good. But once I bend the wires at the back of the sensor itself my meter reads "0". Wires are shorted together and it's a bad sensor. Whole lot easier to bench test than when installed in the trans bell housing.

BTW, while you may pay less for a crank sensor online, if you need one, often it may be better to buy it from a dealer where you're seeing someone eye-to-eye.
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96 4.0 ZJ Laredo, 2004 4.7L WJ Limited, 93 4.0 XJ (spare), 96 4.0 XJ (son's)

-Stalling ZJ? 12 things to check before replacing a sensor; the Dirty Dozen
-Crankshaft position sensor multimeter test. & video of testing.
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Unread 07-18-2013, 11:52 AM   #52
2tall2slow
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O L is what meter read before testing, and with black pin to middle and red to far right power pin, still read 0 L. I was told that meant dead sensor, you are saying O L is in fact a good reading..i already purchased the new sensor and installing myself after work. i dont want any resistance in my sensor, correct?
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Unread 07-18-2013, 02:00 PM   #53
dellis
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Quote:
Originally Posted by 2tall2slow View Post
O L is what meter read before testing, and with black pin to middle and red to far right power pin, still read 0 L. I was told that meant dead sensor, you are saying O L is in fact a good reading..i already purchased the new sensor and installing myself after work. i dont want any resistance in my sensor, correct?
The language of reading resistance confuses about 80% of people, it seems, and open loop also confuses people. There is actual electrical resistance that can be present in a circuit, and then there are resistance numbers that are displayed on your meter. Two different things. You no resistance displayed on your meter - that is, you want no actual numbers being displayed. No resistance displayed is NOT zero resistance.

The resistance test will "pass" if the measurement reads a very high resistance (like 100,000 or more ohms), and the resistance test fails if the measurement reads zero or very little ohms. The sensor is clearly bad if this test fails. Other tests will need to be done if the sensor passes this test.

So, if you have your meter setting on the 1K to 10K setting, you should see OL (for open loop) or 1. or flashing. If, instead, you are actually seeing some resistance numbers, then your sensor is clearly bad.

Is that clear?
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Unread 07-18-2013, 02:19 PM   #54
2tall2slow
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Indeed confusing, but clear. Thanks again, will update my progress soon.
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Unread 07-18-2013, 02:33 PM   #55
Uniblurb
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Quote:
Originally Posted by dellis View Post
The language of reading resistance confuses about 80% of people, it seems, and open loop also confuses people. There is actual electrical resistance that can be present in a circuit, and then there are resistance numbers that are displayed on your meter. Two different things. You no resistance displayed on your meter - that is, you want no actual numbers being displayed. No resistance displayed is NOT zero resistance.

The resistance test will "pass" if the measurement reads a very high resistance (like 100,000 or more ohms), and the resistance test fails if the measurement reads zero or very little ohms. The sensor is clearly bad if this test fails. Other tests will need to be done if the sensor passes this test.

So, if you have your meter setting on the 1K to 10K setting, you should see OL (for open loop) or 1. or flashing. If, instead, you are actually seeing some resistance numbers, then your sensor is clearly bad.

Is that clear?
I'll take your word for it dellis and I may be one of those confused people while I'm sure you know a whole lot about resistance/metering than me.

Have to give you credit 2tall2slow for installing that new Mopar crank sensor all by your lonesome! And you said you weren't mechanically inclined...huh. Hope that fixes your problem but if for some reason it doesn't your crank sensor was bound to fail sometime anyhow.
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96 4.0 ZJ Laredo, 2004 4.7L WJ Limited, 93 4.0 XJ (spare), 96 4.0 XJ (son's)

-Stalling ZJ? 12 things to check before replacing a sensor; the Dirty Dozen
-Crankshaft position sensor multimeter test. & video of testing.
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Unread 07-18-2013, 03:16 PM   #56
dellis
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Uniblurb, I did some checking (to make sure that I'm not the confused one).

(1) I have two good CKPS in my private stash (a Mopar and Standard) ... the Mopar was OL across all connectors, but the Standard was 3,800 ohms across 1 & 2 and OL across 2 & 3. Neither resistance value is "low", but the Standard would have caused me to replace it had I done a resistance measurement on it since it would have clearly displayed on a 1K to 10K setting.
(2) Now, these CKPS units are for a '98, and the test procedure that you had on the previous page is identical to the tests I see in my 1993 manual. But, when I look at my 1998 manual, the resistance tests for a CKPS are not there. Perhaps they proved unreliable???? Anyway, there is only the voltage test from the PCM and a signal monitoring test while engine running (scope monitoring the signal) or slowly turning the engine (multimeter monitoring the signal).

Also 1998 CKPS connectors do not have A B C terminals, and they do not have the same design as what you show on the prior page (and I have in my 1993 service manual). This leads me to believe that Chrysler changed the CKPS design, specs, and testing procedures sometime between '93 and '98.
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Unread 07-18-2013, 05:43 PM   #57
2tall2slow
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Dellis, i should have probably asked you 2hours ago, but can u let me in on those " secrets" to removing my crankshaft sensor? Laying on my back under the jeep holding my ratchet w 12in extenstion and swivel sprocket for hours, my arms are getting tired. I think i loosened in haha. Plz help.
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Unread 07-18-2013, 05:51 PM   #58
dellis
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On a 1998 4.0 .... took me about 15 minutes the last time I did this.

(1) Disconnect CKPS near the firewall.
(2) Tie a long string onto the CKPS connector (you will use this for threading).
(3) Use a long extension (mine was 24"), a swivel style universal joint (NOT a knuckle style universal joint), and 13 mm regular socket to loosen the bolt. Without these tools, it will be a loooooooooooooooooong day.
(4) Pull out CKPS and bracket ... be careful not to lose that bolt.
(5) You will be able to put your arm vertically in a space between the CKPS location and the front of the Jeep. Move the shifter cable out of the way close to the CKPS ... you will be able to lodge it in a position where it will not interfere.
(6) Make sure your new CKPS has a cardboard spacer. If not get one on it.
(7) Disconnect the string from the old CKPS and tie it onto the new CKPS connector - I would suggest you tie to the connector and not the wire so as not to accidentally damage the wire. Go back up to your engine compartment and gently pull the new CKPS up so that the connector is close to it's mate. You may need to reach behind the valve cover to dislodge it if it becomes bound. Tie off your string.
(8) Going back through that access between the CKPS position and the front of the Jeep, reach your arm up and position the new CKPS in it's hole. Place the bracket in its position, aligned with the hole.
(9) While holding the CKPS and bracket in place with your right hand, raise the extension/swivel/13mm with the bolt and insert into the hole. Press down on the CKPS as you are tightening to ensure it is in its proper place.
(10) Check torque ... move shift cable back into place (touching bracket).
(11) Remove string and connect CKPS to harness.
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Unread 07-18-2013, 06:26 PM   #59
ZeeJay1997
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If you have a helper up top it goes a lot better. Seems like I took the bolt out of the dipstick tube and moved it aside.
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Unread 07-18-2013, 10:18 PM   #60
2tall2slow
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You know, within the last twelve months i've taken on the responsibility of repairs on both my '94 and my '98. With the direction of my dad(whos more racer than mechanic) i have diagnosed and replaced starters, alternators, distributers, disc brakes, etc. Actually last week was the 1st i'd ever changed plugs and wires! As of today i have a greater respect for the common mechanic..its work. Today i tackled my '98's crankshaft sensor replacement. Hours..i am officially in the curse word inventers hall of fame. Wanted to quit, kept thinking of a way out..you guys KNOW what i mean. Eventually i got to hear the prettiest sound i've heard in days, my engines' crank. Big big thanks and appreciation to zeejay, dellis and uniblurb!! U GUYS walked me thru and stuck with me. Knowledge is power.
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