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Unread 07-30-2015, 10:50 PM   #1
variable
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1993 ZJ 
 
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CPS Question

So, when I picked up my ZJ and started going through the whole replace this and that rigamarole, it was equipped with this guy:


When I went to replace it, all I could find was the usual metal bracket one... so thinking there was some change over the years, I modified the bracket so that it fit (extra washers etc.)

I picked up a snapon mt2500 and one of the diag screens said "11 no crank reference signal". From googling, it looks like the original CPS was from a Dodge 1500 (95 ish?)... I'm going to pull it this weekend and take a closer look, but I'm wondering now which side I put the washers on... :-P Seems to run ok, but is hard to start.

Anyhoot, was curious if anyone else had that type of CPS?

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Unread 07-31-2015, 09:36 AM   #2
MrRoundel
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It would seem to me that using anything other than the proper Mopar part for your ZJ is an unnecessary gamble. Anything that either uses a weaker magnet on the sensor, or perhaps sets it further out from the "tone-ring" than spec., may weaken the signal and confuse the computer. Never having been inside my engine and/or bell-housing, I can't say exactly what damage might be caused by having the sensor set too deeply, but something damaging, at least to the sensor itself, will probably occur, depending on the end depth. Good luck.
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Unread 07-31-2015, 09:39 AM   #3
ZeeJay1997
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I'm not going to be a lot of help here but if you dont get the spacing from the fly wheel correct, it's going to have a bad outcome. also, the reference voltages changes to 5v on the later ZJs.
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Unread 07-31-2015, 09:40 AM   #4
variable
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Well, keep in mind, thats what was installed when I got it. I took a look this morning and fortunately I didn't do something completely stupid, and the washers were just to make up for the bolts being too long, so it has the 'correct' replacement part.. just weird that the original was so visibly different. But makes me wonder what differences (if any) there are internal to the sensor itself. Maybe the plastic housing is nothing more than a vibration damper or some sort of protective piece due to some odd difference in something completely unlrealted in the 1500's - more prone to heat in that area..etc..
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Unread 07-31-2015, 09:43 AM   #5
variable
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Quote:
Originally Posted by ZeeJay1997 View Post
I'm not going to be a lot of help here but if you dont get the spacing from the fly wheel correct, it's going to have a bad outcome. also, the reference voltages changes to 5v on the later ZJs.
Changes to 5v from what? It didn't seem to make a difference (pre-rebuild) when I replaced the CPS to the one thats on there now, and I remember when installing it checking to make sure that where it mounted would put it [the sensor] in the same place as the original (1500). So positionally I think they came out the same. Functionally... *shrug*
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Unread 07-31-2015, 09:44 AM   #6
variable
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I'm also still very curious about the message in the scan tool about no crank reference. No codes are thrown... if its referring to the CPS, I'm curious what it would do if I unplugged it (I'd test this but I'm tired of cutting up my hands reaching back there..)
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Unread 07-31-2015, 10:16 AM   #7
MrRoundel
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Not everyone realizes that ZJ's are very finicky when it comes to the sensors. The PO, and/or his/her mechanic, may be one of those who thinks "a sensor is a sensor", providing it lines up with the bolt holes, and looks close. With yours, the bolts may not actually be too long, but the part itself is too thin. Or, as ZeeJay1997 mentioned, it may generate a signal with a different voltage value. This may, in turn, make the computer disregard its input as if it's not there. Again, from everything I've read here over the past couple of years, it's best to use Mopar or true OEM that is made for the particular vehicle. Otherwise it adds extra uncertainty to the troubleshooting equation. At least it would to me. I'd want to check it off, not circle it in order to come back to it later if all else failed. The fact that your nice scan tool points to the CPS, and yours is a bit different from OEM spec's, would make me lean heavily there as it being the problem. Of course, it's not my money or time we're talking about. Good luck.

Oh, and BTW, I think that your computer may already be unplugging it. Maybe not though, and perhaps you would find that it ran differently with it removed. That would tell you that there must at least be a signal from the part, and that the scanner may be in error, at least in its wording of the problem.
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Unread 07-31-2015, 10:34 AM   #8
variable
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Oh, I've definitely noticed the finicky-ness... As for the bolts - I say bolts because the name of the 'bolt' that requires an allen wrench and actually has a round top is eluding me at the moment (thus cut up hands...) - I'm pretty sure they were intended to go with whatever the previous owner had on there. You can see from the pic above that the mounting holes are actually quite thick. The washers I added (and glued together...) were only there to make up that difference. Though now that I know what the deal is, (and am feeling motivated), I'll replace them with real bolts that don't require several beers and some whiskey to remove (and lots of cursing).

The sensor that's in there now - while not a mopar part - looks identical to the mopar part, so while I may not be getting mopar quality and accuracy (and the possibility its not working at all..), I'm now 99% certain that at least the size and alignment is correct. I'll have to trace the wires back and see if there's a better location for me to tap into them and see what kind of readings I can get. There's like 1 position in which I can get my inspection mirror back there and actually see the damn thing.

I may replace the sensor anyway.. I installed it after rebuilding the engine, but before installing the engine, so I wouldn't be surprised if it got banged around pretty good when trying to shimmy the engine in there (that f*cker is heavy!)

On an entirely unrelated note, while attempting to troubleshoot the air conditioning, I found it laughable just how much data is fed to the climate control display. I cracked up when I found the bit about being able to read the engine RPM on there. More so when I tried it. Still haven't found the leak though..
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Unread 07-31-2015, 11:37 AM   #9
ZeeJay1997
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The older ZJs have 8v sensor reference from PCM. The newer ones use 5v.

I really can't visualize the physical aspects of it cuz i've never messed with a 93 V-8.

What i was trying to get at is that if someone made something fit, it could be the wrong sensor.

Pic of newer model sensor.

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Unread 07-31-2015, 11:47 AM   #10
variable
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Wow, thats way different... This is what I get when I look for my year:


Whats interesting is on Amazon, I actually see both the version you show and the one in this post as "fitting" my ZJ... I'm not actually sure how I'd mount yours (I'm guessing there's a bolt hole I've not noticed...) Also, the one I posted seems to 'fit' in a hole that seems almost molded just for it..
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Unread 07-31-2015, 11:56 AM   #11
ZeeJay1997
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That one looks correct from what I find. Your Jeep takes a Mopar 56026701 / 70104291

It it fits

DODGE B150 (1990 - 1993)
DODGE B250 (1990 - 1993)
DODGE B350 (1990 - 1993)
DODGE D150 PICKUP (1990 - 1993)
DODGE D250 PICKUP (1990 - 1993)
DODGE D350 PICKUP (1990 - 1993)
DODGE DAKOTA (1990 - 1993)
DODGE RAMCHARGER (1990 - 1993)
DODGE W150 PICKUP (1990 - 1993)
DODGE W250 PICKUP (1990 - 1993)
DODGE W350 PICKUP (1990 - 1993)
JEEP GRAND CHEROKEE 1993
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Unread 07-31-2015, 12:02 PM   #12
variable
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Looks like the one you posted fits some odd combos:
2002 Ram 2500/3500 5.9l v8
1994/95 Cherokee 4.0
1994-96 Grand Cherokee 4.0

The 5.9 is interesting.. ah well..
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