2007 5.7l HEMI stalling issue - but different!? PCM? - JeepForum.com
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post #1 of 20 Old 12-29-2016, 01:27 PM Thread Starter
aluminium
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2007 5.7l HEMI stalling issue - but different!? PCM?

My 2007 5.7l Hemi is having a transmission issue that the local dealer and Star Center can't 100% figure out and I'd like some other opinions on this before they go replacing parts on my dime.

I've worked my way through this monster of thread ( jeepforum.com/forum/f67/2007-jeep-grand-cherokee-overland-stalling-problem-1147825/index32.html
), trying to see if this is the same problem I am having, but everyone there seemed to be having stalling issues at low speeds or idling and I'm not this is the same problem.

When traveling at highway speeds (60+ mph), my car will
  • randomly give a loud "thunk" as if it missed the gear or downshifted very hard,
  • shake everyone awake,
  • dash warning light will flash
  • and a beep is heard
.

After everyone asking "what the heck was that?" it will drive normally again. Recently the issue has been happening more often and I also had a full loss of power that required me to pull over and restart the car on the highway.

This mainly happens going up- or down a hill and I believe when the RPM is <2200 with the foot off the gas.

So far the dealer has(I'm transcribing off a wall of text here):
  • Error P0884
  • verified PCM software is up to date
  • inspected PCM connectors
  • inspected C104 Connectors
  • inspected wire harness & various connections
  • performed wiggle test while monitoring trans relay
  • cleaned & tightened G100&G101 ground
  • verified proper transmission to Solenoid relay
  • swapped relay for diagnostic

at this point they opened a Star Case and escalated to Jeep
  • -cleared DTC's & inducing engine coolant temp sensor DTC then road check if coolant sensor DTC is no longer present due to possible ignition voltage spike
    ->DTC remains yet still possible ignition related (inconclusive)
  1. -inspected ignition coil electrical connections
  2. -removed coils to check for burns/abnormalities ->no abnormalities
  3. -recorded & transferred data to Star

Star now thinks that the PCM is the culprit and should be replaced, but they aren't be completely sure.

I'd be thankful for every extra opinion and possible other(namely cheaper) solution.

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post #2 of 20 Old 12-29-2016, 02:39 PM
RCS1300
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I would go with basics - compression test each cylinder and then perform a leak down test on each cylinder. This is to make sure you are getting the right amount of compression for ignition and that the valves are working/sealing correctly. Get someone that knows what they are doing especially with the leak-down test. Not many people know how to perform that test correctly - even the dealer people.

Did the Dealer mechanics find any misfires in any of the cylinders. Sometimes you can have a significant number of misfires but NOT throw a diagnostic code.
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post #3 of 20 Old 12-29-2016, 07:39 PM Thread Starter
aluminium
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Originally Posted by RCS1300 View Post
Did the Dealer mechanics find any misfires in any of the cylinders. Sometimes you can have a significant number of misfires but NOT throw a diagnostic code.
Not that I know of. What I wrote above is pretty much what I got back from them.
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post #4 of 20 Old 12-30-2016, 05:07 AM
RCS1300
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Quote:
Originally Posted by aluminium View Post
Not that I know of. What I wrote above is pretty much what I got back from them.
What was causing the dash warning light to flash? I am assuming that was your check engine light or was it some other light flashing?
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post #5 of 20 Old 12-30-2016, 08:42 AM Thread Starter
aluminium
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Originally Posted by RCS1300 View Post
What was causing the dash warning light to flash? I am assuming that was your check engine light or was it some other light flashing?
Check engine light - it goes on when this "thunk" happens, but immediately goes off again.
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post #6 of 20 Old 12-30-2016, 09:52 AM
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Quote:
Originally Posted by aluminium View Post
My 2007 5.7l Hemi is having a transmission issue that the local dealer and Star Center can't 100% figure out and I'd like some other opinions on this before they go replacing parts on my dime.

I've worked my way through this monster of thread ( jeepforum.com/forum/f67/2007-jeep-grand-cherokee-overland-stalling-problem-1147825/index32.html
), trying to see if this is the same problem I am having, but everyone there seemed to be having stalling issues at low speeds or idling and I'm not this is the same problem.

When traveling at highway speeds (60+ mph), my car will
  • randomly give a loud "thunk" as if it missed the gear or downshifted very hard,
  • shake everyone awake,
  • dash warning light will flash
  • and a beep is heard
.

After everyone asking "what the heck was that?" it will drive normally again. Recently the issue has been happening more often and I also had a full loss of power that required me to pull over and restart the car on the highway.

This mainly happens going up- or down a hill and I believe when the RPM is <2200 with the foot off the gas.

So far the dealer has(I'm transcribing off a wall of text here):
  • Error P0884
  • verified PCM software is up to date
  • inspected PCM connectors
  • inspected C104 Connectors
  • inspected wire harness & various connections
  • performed wiggle test while monitoring trans relay
  • cleaned & tightened G100&G101 ground
  • verified proper transmission to Solenoid relay
  • swapped relay for diagnostic

at this point they opened a Star Case and escalated to Jeep
  • -cleared DTC's & inducing engine coolant temp sensor DTC then road check if coolant sensor DTC is no longer present due to possible ignition voltage spike
    ->DTC remains yet still possible ignition related (inconclusive)
  1. -inspected ignition coil electrical connections
  2. -removed coils to check for burns/abnormalities ->no abnormalities
  3. -recorded & transferred data to Star

Star now thinks that the PCM is the culprit and should be replaced, but they aren't be completely sure.

I'd be thankful for every extra opinion and possible other(namely cheaper) solution.
Hi aluminium,

I'd be happy to follow up with your dealership for you if needed. Just PM our page with your VIN and let me know!

Andrea
Jeep Social Care Specialist
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post #7 of 20 Old 12-30-2016, 12:33 PM
RCS1300
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A word of caution. Jeep Dealers are independent Companies and Jeep has no control over the mechanics technical competence or general competence. So, unless your vehicle is under warranty, I would get a second opinion from a known qualified local mechanic before I made any new parts expenditures.

I would go to a few different repair shops and ask - "when you have a really difficult diagnosis where do you send your work?". Find that person to help you.
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post #8 of 20 Old 12-30-2016, 02:09 PM Thread Starter
aluminium
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Quote:
Originally Posted by RCS1300 View Post
A word of caution. Jeep Dealers are independent Companies and Jeep has no control over the mechanics technical competence or general competence. So, unless your vehicle is under warranty, I would get a second opinion from a known qualified local mechanic before I made any new parts expenditures.

I would go to a few different repair shops and ask - "when you have a really difficult diagnosis where do you send your work?". Find that person to help you.
Thanks, I understand that. Actually I started out at a qualified local mechanic, that comes highly recommended, and he sent me to a Jeep dealership as the error was too wonky for him and he wasn't able to fully read the error code.
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post #9 of 20 Old 12-30-2016, 02:13 PM Thread Starter
aluminium
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Quote:
Originally Posted by JeepCares View Post
Hi aluminium,

I'd be happy to follow up with your dealership for you if needed. Just PM our page with your VIN and let me know!

Andrea
Jeep Social Care Specialist
Can't send private PMs yet, as my post count is still too low on this forum. Any other way to reach out?
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post #10 of 20 Old 12-31-2016, 08:07 AM
LouC
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Did you do the ignition switch recall? We had some of those odd symptoms (not the thunk and hard shifting) check engine light and a series of random codes; heater fan would turn off and tach & speedo all cycle back and forth. Engine ran normally though. All fixed by switch replacement.

2017 JK Unlimited Sport 6 spd
2007 WK Limited Hemi QDII
1998 ZJ Laredo 4.0 Selectrac
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post #11 of 20 Old 01-02-2017, 02:46 PM Thread Starter
aluminium
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Originally Posted by LouC View Post
Did you do the ignition switch recall? We had some of those odd symptoms (not the thunk and hard shifting) check engine light and a series of random codes; heater fan would turn off and tach & speedo all cycle back and forth. Engine ran normally though. All fixed by switch replacement.
I have not - might be a good try though. Thanks
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post #12 of 20 Old 11-07-2017, 05:05 AM
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Hi Guys,
Ive got exactly the same failure on my 05 Hemi...
Did you solve the problem?
Ive found that the voltage of the tcm says about 7V, if I stuggle on c4 connector the voltage changes from 3V to 8V.
Hoping its just the connector and not the pcm...
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post #13 of 20 Old 11-08-2017, 07:07 AM
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How much is the PCM to replace? I'd probably do that if they're recommending it. Sometimes intermittent electronics failures can be hard to diagnose.

When was the last time your transmission was serviced? Did this problem manifest itself just recently? How long have you owned the car? Which transmission do you have?

2007 Jeep Grand Cherokee Overland
5.7 Hemi - Airaid CAI - Magnaflow
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post #14 of 20 Old 11-09-2017, 03:47 AM
balu47877
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the pcm is about 500$, but i dont know if this will fix the problem... it could also be just a faulty sensor, or a bad ground, cable, whatever...
I hope that aluminum can tell me his fix
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post #15 of 20 Old 11-09-2017, 05:55 AM
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Quote:
Originally Posted by balu47877 View Post
Hi Guys,
Ive got exactly the same failure on my 05 Hemi...
Did you solve the problem?
Ive found that the voltage of the tcm says about 7V, if I stuggle on c4 connector the voltage changes from 3V to 8V.
Hoping its just the connector and not the pcm...
Always start diagnosing this kind of stuff with wires and connectors. I had a car that had starting problems. Told mechanics to check the wiring of the steering column, but no, as they obviously had sh*t for brains, they replaced ECU, gateway, gauge cluster (or whatchummacallit) + whatnot, only to realize in the end that the whole problem was caused by a single chafed wire, guess where... Cost: over 2000$
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