Won't start. Crank Position Sensor issue? - Page 2 - JeepForum.com
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post #16 of 32 Old 06-12-2021, 06:20 PM
Dust Devil
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Yesterday I was shopping for an OBD-2 scanner and saw lots of not terribly clear information. I would love a $700 Autel but it sounds like most of the stuff I would need for a 22 year old Jeep is in an $80 scanner from Harbor Freight.

What I found when I was looking for that is that in a WJ, you can do: key on, key off, key on, key off, key on within 5 seconds, then the odometer LCD will list your OBD-2 stored fault codes. I did it this morning and got P0320: NO CRANK REFERENCE SIGNAL AT PCM.

On pages 140-144 of my newly acquired 1999 Jeep Grand Cherokee Powertrain Diagnostic Procedures manual, there is a list of possible causes and a flow chart style diagnostic testing procedure.

I'm going to go through the procedure but at this point it feels like the sensor is the likely cause.

I would have done the key thing before I bought the car if I had known about it...



p.s. I'm probably going to chop the harness and sensor sides of crank sensor wiring at the salvage yard so I can make a diagnostic connection. I might do the same for the cam sensor. If there is a way to make a sensor ground connection at the PCM, that would be handy too.


Last edited by Dust Devil; 06-12-2021 at 06:36 PM.
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post #17 of 32 Old 06-13-2021, 04:33 PM
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Originally Posted by Bigrigr View Post
Where did you get the Mopar reman unit? I didnt think there were any Mopar sources for these any more?
Mopar never "remanufactured" anything ~they bought used salvage pcm's from running wrecks out of chain salvage operations that test and tag them when they come in.

No repairs of any kind are done, they soda blast them to clean them up and on goes an orange Mopar reman tag in conjunction with a software update and vehicle specific flash programming.

The exact same thing I do for you guys when you slide into the pick and pull on the cheap and send a pcm to me, the difference is that dealer sourced reman is significantly more expensive all in.
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post #18 of 32 Old 06-13-2021, 08:50 PM Thread Starter
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Quote:
Originally Posted by Waterluvr View Post
Mopar never "remanufactured" anything ~they bought used salvage pcm's from running wrecks out of chain salvage operations that test and tag them when they come in.

No repairs of any kind are done, they soda blast them to clean them up and on goes an orange Mopar reman tag in conjunction with a software update and vehicle specific flash programming.

The exact same thing I do for you guys when you slide into the pick and pull on the cheap and send a pcm to me, the difference is that dealer sourced reman is significantly more expensive all in.
How much are yours? Seems like a great option to use yours if one is not in a hurry to repair.

Based on your experience, what's the average lifespan of a reman unit before it fails again?

What is a "soda blast?" What software update does Mopar do (beyond the VIN)? Thank you for your insights.
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post #19 of 32 Old 06-14-2021, 09:27 AM
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Originally Posted by Jeepsmsc2 View Post
How much are yours? Seems like a great option to use yours if one is not in a hurry to repair.

Based on your experience, what's the average lifespan of a reman unit before it fails again?

What is a "soda blast?" What software update does Mopar do (beyond the VIN)? Thank you for your insights.
Based on the input from member's here anything that's actually been repaired as a core return has nearly a 50% defect rate out of the box and the rest of them rarely run for long. These were NEVER made to the same standard of quality as Bosch or Denso modules and weren't constructed to be repaired.

I don't sell pcm's, pick and pull yards are full of them usually in the $50.00 range that haven't been molested. Soda blasting is a less evasive process than sand, great for cleaning corrosion off without damaging the substrate.

I conduct a full reflash with software updates thru Chrysler Tech what they charge varies on the make, model and year but it's very cost effective all in versus anything that's been tampered with.
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post #20 of 32 Old 06-14-2021, 10:52 AM
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So I was shopping for a new Mopar crank position sensor. The cheapest I found was $97 on Amazon.

I called up my local dealer and $186.

I told him I had to shop around, I found it on Amazon for $97 but wanted to shop local.

He said let me see what I can do: $112.

Sold.

In stock, no waiting, if I have a problem, I'll take it to them with a receipt rather than mess with Amazon. That's worth $15 to me.

It never hurts to ask.
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post #21 of 32 Old 06-14-2021, 04:50 PM
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I'm going to try one of the "easy" crank sensor swap procedures:


With this one the Jeep wasn't jacked up, the trans crossmember wasn't lowered, the transmission shift linkage wasn't taken apart and the interior wasn't disassembled.

It sounds too good to be true but it's worth a shot before I decide if I want to do the interior and maybe need a helping hand or do the crossmember or shift linkage.

There seems to be a lot of conflicting info on this sensor swap. I'm thinking motor mounts sagging or some other tolerance stack is making one method easier than another for some people.

I'm going to keep my fingers crossed and hope mine is easy.
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post #22 of 32 Old 06-14-2021, 05:51 PM
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I had to replace CPS in both my 97 and 02 Grand Cherokee's. The 97 was quite a pain, but nowhere near as bad as the 02. The 02 actually has an access plate behind the dash, I had to search multiple You tube vids before I found this out. Even so the hole is really in the wrong place, and nowhere near big enough to get a hand in there, while not easy to get out, it's a lot harder to get the new one in. My solution let a mechanic do it. Not worth the aggravation to do yourself !
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post #23 of 32 Old 06-15-2021, 08:10 AM
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So I got under there and I'm not going to say it's impossible but there is no way.

I'm not sure what it is but there is a hard line almost blocking the bolt head.

I could get my socket to the bolt head but I have no idea if I could get it to engage the head.

From on top I couldn't see a way to get my hand back there to put the new sensor in. I certainly couldn't get there from below.

My phone has a NWS Excessive Heat Warning...

Rather than tear my interior apart or get in too deep trying to drop the crossmember, I think I'm going to punt and see if I can find a sucker, I mean a shop to do the swap.
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post #24 of 32 Old 06-15-2021, 06:32 PM
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Quote:
Originally Posted by Dust Devil View Post
So I got under there and I'm not going to say it's impossible but there is no way.

I'm not sure what it is but there is a hard line almost blocking the bolt head.

I could get my socket to the bolt head but I have no idea if I could get it to engage the head.

From on top I couldn't see a way to get my hand back there to put the new sensor in. I certainly couldn't get there from below.

My phone has a NWS Excessive Heat Warning...

Rather than tear my interior apart or get in too deep trying to drop the crossmember, I think I'm going to punt and see if I can find a sucker, I mean a shop to do the swap.
This is one job , that I say pony up and pay someone else ! Get a price first ! And make sure they use OEM ! I paid a place to put one in my 97, it was not OEM and did not work. They lied to me ! Also pay by credit card, I paid cash back then, couldn't fight them. But if you pay by credit card and it doesn't work, you can deny the charge!
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post #25 of 32 Old 06-15-2021, 07:06 PM
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When I did my crank sensor I used a 3 foot extension and a swivel at the socket. I wrapped some tape around the joint of the swivel to keep it from just flopping and made the socket stand outward. I snaked the extension over the top of the cross-member, then undid the bolt. Then I unplugged the sensor from it's connection and wrapped about a 3' piece of bailing wire around the undone plug of the sensor. Then reached my hand down to the crank sensor and grabbed ahold of the wire, wiggled it out of the hole a little, then turned the sensor 180 degrees and pulled it out. You have to turn it for it to come out. Next I pulled the sensor out to the right side of the engine (when facing it). The bailing wire I twisted on the end of the plug followed though the back side of the engine as I brought out the sensor. Took the old one off the wire and twisted the bailing wire around the new sensor, and pulled the sensor connector back through behind the engine to its connector. Installing in new sensor was opposite, so it has to be 180 degrees off again, and when it got down low enough, twisted it into place. As far as getting the bolt back up into place, I put some axle grease in the end of the socket to hold the bolt in the end of it, then snaked the extension back and bolted it in. It's kind of a balancing act. For got I also put a shop light on top of the transmission and aimed it at the sensor to see where I was going.

I had it done in 1/2 hour and didn't struggle with any of it. I got barney rubble forearms didn't have an issue reaching behind the engine to get the sensor out. Just removed the airbox assembly.

I will admit I didn't put the little wire protector guard back on, but if someone can tell me why I really need that there, I'll pull it back out and put it back on.
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post #26 of 32 Old 06-15-2021, 08:33 PM
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I got a quote for $145 from the shop I was recommended to. Easy money for them, they probably have a lift and a rolling transmission jack. It's probably a 15 minute job when you have that. I'm providing the OEM sensor so no worry about a cheapo unless they try to keep mine.

I think $145 is reasonable, if the job turned in to 5 hours of pain for me, I would gladly pay $30/hour to avoid that since I would be working under a Jeep lying on rocks in 100+ heat.

Hopefully sooner than later, I'll have my own shop with a lift, AC and a rolling transmission jack, then I'll be doing the 15 minute jobs myself.

This year I have had several times when I've had to do hard, exhausting work during my move to Nevada. I'm going to push the easy button this time and feel good about it.
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post #27 of 32 Old 06-18-2021, 01:57 PM
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It took about 26 hours but my sensor has been changed.

I drove for quite a while including several very slow speed laps around my block to try to get heat in it and confirm that the problem is fixed. So far so good. I'm going to keep testing it for about a week before I start venturing out in to places where a breakdown would be inconvenient.
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post #28 of 32 Old 06-18-2021, 07:23 PM
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It took about 26 hours but my sensor has been changed.
Did you do it yourself? What do think the actual wrench time was?
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post #29 of 32 Old 06-18-2021, 08:37 PM
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They couldn't get to it yesterday (I brought it in at about 8:30), then they called me to say it was done around 9:30 today, then it took me a while to pick it up.

I'm guessing less than 1/2 hour on a lift. When you can lift it and then drop the transmission crossmember by 8-12", you get plenty of clearance. With a pedestal style transmission jack and an impact wrench on a Jeep with no rust, dropping the crossmember and putting it back probably takes 5 minutes total. If you still have to disconnect the shift cables from the transmission, that might add another 5 minutes. 2-3 minutes to get the car up and down on the lift, then the sensor replacement itself is one bolt and one electrical connector, that should only take a couple minutes if you can reach.

That could be 10 minutes if everything went right. I bet they have done it before because they knew exactly why I was doing it.

If the new OEM sensor lasts a reasonable amount of time, I'll have a shop with AC and a lift by the next time I have to do that job. Then I'll be patting myself on the back for saving $145 without breaking a sweat.

If I needed to save the $145 this time, it very likely would have been a big, long, sweaty pain in the *** done in 100+ heat.
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post #30 of 32 Old 06-18-2021, 09:05 PM
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Right on, glad you got it fixed. I've experienced this kind of repair before where doing it on one vehicle can be different on another of the same 'model". The common one seems to be taking the dash out of vehicles.

145 actually sounds really reasonable. I wouldn't have thought twice about charging that for a fam.
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