2011 JK - PCM seems to 'restart' on ignition attempt.

[Deleted member 48574]

Hey Overlanders,

Title should read "ECM" not "PCM" - can a Mod edit that for me as I cannot?

Had the JK for a year and a bit now, and managed to clock up 40k kilometers.

The other day, I noticed my dash lights were dimming, then brightening. My headlights were doing the same.

I arrived at my destination and sat waiting for my dear lady to arrive, and I have the engine off but the ignition on to listen to Radio.

When she arrived, I went to start the JK, and there were 3 clicks, followed by dead everything. No lights. No ignition. Literally everything was dead.

It didn't make sense for it to be a totally dead battery, so I popped open the fuse box and looked around for anything that was burnt out. Nothing.

I then tried to start it again, and as soon as I turned the key, it fired right up without an ounce of problem. The best way I can describe it is it seems like the entire ECM/electrics of the car decided to do a hard reset. I could almost hear the Windows chime as the thing rebooted

It happened to my lady again yesterday.

Anyone heard of this problem? The dealer's advice was to "bring it in when it's happening". I got angry at that as they clearly were not listening to the problem.

It's unpredictable and so far it has restarted every time but it's just not right for a newer vehicle to behave this way. What if I'm 250 km down a forest service road and it DOESN'T restart, right? (I have comms and contingencies of course but would rather not have to use them because of a preventable problem)

Thoughts, opinions, etc?

Cheers
Craig

 

[Funkicidal]

With your dash and head lights dimming, that sounds like when I have had alternators go out on me, but being able to sit and listen to the radio and then be able to start it wouldn't happen if your battery had been discharging while you were driving.

I would start at the battery and check both terminals for a loose cable, then follow each cable on the other end for a good connection. The negative cable will connect to the chassis for example and make sure it is a good connection.

While you are at the battery, give it an inspection as well. It should either have an inspection port or caps you take off to see the level of water in it - if it is low on water that could indicate cycles of discharging/charging.

 

[Deleted member 48574]

Thanks for the tips funk. I will go through all that either this afternoon or tomorrow!

Cheers
Craig

 

[Gear]

On my 2007 JKU(automatic) I use to have a problem were I would turn the key and only get a click sound. I soon figured out that if I drop the transmission down into neutral the Jeep would start right up. Might try this as a backup. Seems the computer was thinking that the Jeep was in gear and would not allow it to start. I believe it has to do with the neutral safety switch. Might search more on the Jeep specific forum.

 

[JIMBO]

:sombrero: Simple check of the electrolyte level in the battery-

Mine is over 4yrs old now and has been "BARELY" low, but the JK/JKU ECM-rquires pretty close to 12 .6 volts-minimum maintained, to work successfully !

:costumed-smiley-007:wings: JIMBO

 

[jeep-N-montero]

Just put an Optima or Diehard battery in and stop worrying about it, my Jeep was acting the exact same way before I swapped in an Optima and had zero issues since. My ECU would reset because the starter was drawing all of the power to get it started and I would have to re-enter all of the info for the vehicle information center.

 

[Desert Magazine]

i had a similar issue with my tj 2005 jeep. my situation started last year as we came out of the movies... click-click-click.... tow truck called and when she was dropped i put the key in and it started??? a few weeks later did the same thing but i fell into the mechanics trap that they said it was a bad fuel pump... got half my money back when i asked how the jeep would click compared to starve for gas... both times it was very humid here in phoenix.... no issues for a year and the first hot humid day...click...click ...click- waited for a minute and starts.... did this 3 times this summer on hot humid days... i went in for an oil change and told my story and service mgr adviced a diagnostic...i told him its been done and nothing found and no bad codes. another tech chimed about the ecm might have issues... in short i just sold her and the new owner knows of the issue.... i wish i was able to correct it...

 

[JIMBO]

:sombrero: Heh Heh, I just read this one again and thought of the battery in your ignition key "chip"-

Checkitout

:costumed-smiley-007:wings: JIMBO

 

[voodoojk]

Just put a new batt in it. The JK, like all Chrysler vehicles, act really strange when the battery gets low. Mine started to honk the horn and then turned every single light on te dash then shut down. Put in a new batt and hasn't done it in 2 years

 

[Deleted member 48574]

The plot thickens.

This morning, the Jeeps speedo starting fluctuating wildly and all the warning lights on the dash started blinking.

I'm now at the dealership and I will post what I find out.

Hate to say It but this is my first new vehicle and I'm not thrilled. Right now Is my second time having an issue with this thing--first time was a clutch problem. The jeep is only a year old and has only 40,000 kms. That means 2/3 of the way through warranty.

If I wanted to do a major unscheduled service every 20k kms I woulda bought a land rover!

 

[Deleted member 48574]

Well now that's interesting.

Apparently there was a loose screw somewhere along the positive battery cable. They tightened it up and cleared the codes and it was good to go.

Seems strange to me as I tightened the batter terminals myself on Sunday but it seems to be working now. Maybe it wasn't a terminal screw -- I will have to wait for the paperwork to figure out more details.

I'm also surprised if it was a lose screw that the engine didn't lose power when the speedo was doing its thing.

As I understand it the Jeep is EFI. Therefore, if the power is fluctuating (which it seemed to be given the behaviors earlier) that the fuel would be inconsistent too, no?

Thoughts? (and thanks a million Goethe help this far!)

Regards
Craig

Thanks all for the help.