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SpazzDMB 11-26-2013 10:39 PM

CPS and limp mode
Hey everyone,

My '05 grand cherokee 5.7L decided it was going to give up on its long streak of good health and have everything go bad at once, so I wanted to see what you guys thought, and see if the dealer is trying to screw me over.. more than usual that is..

While driving down the highway yesterday the engine felt like it downshifted, RPMs dropped to 0, a couple seconds later the RPMs went back to normal, "ESP disabled" came up in the display, the traction control light came on, and the check engine light came on and started flashing. From here on out the jeep remained in limp mode. The code associated with the check engine light was P0335 (crankshaft position sensor). Being in a new town and not knowing any reputable mechanics, I took it to the nearest jeep dealer and here's what they said..
In addition to the P-code it has about 50 other computer codes associated with it, apparently none of the computers in the vehicle are in sync. They said it would be about 5 hours just to trace everything down to figure out what the actual root cause of the problems would be.. (really? 5 hours at $100/hr just to find out whats wrong?)

My hope is that it's just the crankshaft position sensor that has gone bad and has caused all the other computer problems (especially since thats what seemed to kick all of this off). The first mechanic I talked to said its very likely that is the cause, but the guy that was actually going to be doing the work said there is 0 chance that the CPS is causing any other issues.
So with two majorly conflicting mechanics at the same dealer, and the $500 cost to determine the problem, I'd like to get some more opinions..


twistedlizard72 11-27-2013 03:01 AM

1 Attachment(s)
Is it similar to the video in this thread?

My suspicion would be the ignition switch.

SpazzDMB 11-27-2013 05:18 AM

That's not quite what it's doing. It's just the RPMs that drop to 0, and only the traction control/check engine lights come on (and remain on regardless of pressing the on/off button), and the ESP disabled message. I can't tell from the video, but also on mine, when the RPMs drop to zero there is a jerk forward like downshifting, and the engine actually sounds quieter for a second or two.

yzjwk 11-27-2013 02:28 PM

My usual 1st suspect with multiple module failures is power either from the battery itself or from the battery to one of the other main modules (FDCM, FCM,PCM etc) . I would guess that the engine did drop out for a second and then fired back up in which case the cps could possibly be the culprit . or maybe it just lost power or stopped communicating to the PCM . For them to figure out what happened first though would take some looking into . I personally need something to fail more then once for me to say there is a real problem . I would clear the codes and wait for something more conclusive and MHO is any mechanic should be doing the same in this situation . If you have a hard failure , then a quick clearing of the codes and a trip around the block should tell you . If they do that with the starscan connected , then they should be able to tell you if there are any large irregularities . If they don't find anything , take that money you just saved and buy yourself a superchips programmer or a good OBDII scaner/reader and start learning how to use it .

Good luck

SpazzDMB 11-30-2013 11:09 PM

An update on everything for anyone else who has this problem in the future, it was in fact the crank shaft position sensor. Haven't had any problems since getting that replaced and will never be going back to that dealership.. Thanks for the suggestions guys!

Texas WJ 12-26-2013 11:20 AM

Thank you for updating this thread. I just pulled P0315 and P0335 after some stalling issues and suspected it was the crank position sensor. I'm going to give it a shot today.

Jeepforthewin 12-26-2013 01:10 PM

I had the same problem a few months ago with multiple codes and all. A new CPS cleared it all up.

Texas WJ 12-26-2013 02:50 PM

Once I found the location for the sensor it was a 15 minute job. The crank position sensor on the '05 5.7 V8 is on the engine block, passenger side, about 2/3rds back. Pretty easy access but the connector was a pain.

For now it appears to have done the job. $49 for the part from the dealer. (144K miles on the Jeep)

tom19511 12-27-2013 06:54 AM

Replaced mine in a 20 degree garage after it failed almost 2 years ago.. It had rust buildup around it and almost couldnt get it out. Got it out with visegrips. then tried to put it back in it wouldnt fit. had to clean the hole out with a dremel......Good ever since..

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