WMayo

I replaced the key fob batteries about 3 weeks ago, because it quit working. Changing the batteries fixed that, at the time.

Noah911

No key light staying on? Does it flash at first?

Noah911

If you haven't.. In the owners manual there should be a part about a procedure to see about reprogramming the transmitter to the reciever. It is supposed to be done, and sometimes has to be re-done after replacing the battery in your key fob. There are a couple of different ways to do the re-programming
of your transmitter, as it has something of a rolling security synchronisation process about it, to be able to set-up multiple transmitters (remotes).

I am not sure if a procedure like this being done, or re-done.. if it may be a helpful to try it and see.

Noah911

Agreeing there is a major electrical system malfunction occurring. There is a reason for it. What is the reason?

The Automatic Shutdown Relay ASD and security functions would only effect the fueling, by turning it off. It wouldn't turn off all of your gauges and the other electrical components though.

The BCM may be able to turn off your gauges. But, it probably would not turn everything off like is happening though. It would likely throw a check gauge and/or engine light too. If it is the BCM malfunctioning, removing the battery cables to reboot the system I think would re-set the BCM and other problems in some way too though.

Noah911

A SKIM associated problem does not seem like it could be the primary issue to me. I think a problem at the SKIM module would probably result in throwing you code with other similar, but different symptoms.

One good piece of information. I know it might not be something to completely resolve all of the symptoms you are experiencing. It could overall help though.. The alternator - its connections and wires are really important to run everything about your entire electrical system correctly. Undoing the battery to the alternator cable you could clean this connection here at the alternator. Plus, the other connections located here at the alternator too. This could really definitely help things.

You sound like you are saying your Jeep is presenting with major running, and electronic dysfunction right now. I think this would now be the time for using a data reader tool. A high-end professional grade data reader tool would be nice.

I think with a DVOM, you may be able to hopefully also successfully track down where the problem is located too? You should be able to do some testing without having to keep the engine on and running. It sounds like you are having a near-complete systems failure? Something like a short, or any other major disturbance to the electricity somewhere within the system, it could cause the symptoms you are experiencing.

Does it run just idling for any length of time? That would be the most ideal way to run a systems test, is with the engine on running while kept at idle. You can still do it without it running though. You can use the data link connector adjacent to the fusebox at the drivers side kick-board where you plug in and connect to a scanner. The data reader tools utilize a system to communicate for different diagnostics. It may be tapped into easily here at the DLC, at pin #2.. to check and run different testing procedures on your Jeeps computers communications system. It sounds like things here are not communicating correctly right now for some reason?

Do you know how?

Noah911

During this time, when it was randomly dying on you.. did all of your gauges also go dead too, like how they are doing right now?

The way I understand, the Cam and Crank sensors both really only effect a specific variable-set. The spark timing.. backfires, misfiring cylinders, no spark occurring, stuff like that is likely to happen. Both of these sensors are obviously electrically charged components though. They do work synchronously together as part of a whole larger system. But, I do not think they are likely a reason for having a major electronical lock-up and power shutdown occurring.

WMayo

Ok, major update. I did a procedure I found online - disconnect battery neg for 5 minutes, remove PCM fuse also. Return after 5 minutes. With key off, press "Reset" and "C/T" buttons on overhead panel, then turn key on. Release buttons, display says "Test Passed". Car now starts and runs, but no gauges (they work for few seconds then die), windows still don't work, door locks are still iffy. However, car is drive-able. Finally have a code - P1686. Seems to me that SKIM is going bad, and everything I've seen says remove it, replace PCM, and everything will work. If PCM doesn't see a SKIM, it just runs as a non-SKIM unit. That's what I'm seeing online, anyway. At this point, will follow a friend back to Houston - hopefully it will make the trip - so I can get home and then continue to diagnose. I don't have speedometer or fuel gauges, RPM, etc - and have a LOT of warning lights. But pretty sure at this point is a SKIM problem.

Noah911

At least you won't have to worry about all of the gauges and warning lights distracting you in the same normal way while driving now..

With all of your symptoms, P1686 has a good probability of being because of a PCI bus communications system problem between modules. The SKIM code may be a default code displayed coming up now because of a full on disturbance having happened in the system?

You heard to replace the SKIM and PCM?

Noah911

Reading in the owners manual on the SKIM function, on start-up:

It states, " After completion of the bulb test, the SKIM sends bus messages to keep the lamp off for a duration of about one second. Then, the SKIM sends messages to turn the key warning lamp on or off based upon the results of the SKIS self-tests. If the SKIS indicator lamp comes on and stays on after the bulb test, it indicates that the SKIM has detected a system malfunction AND/OR that the SKIS has become inoperative." (end of copy & paste from the owners manual)

On the dash.. That means either the module is bad, or you have an electrical problem..?

If it is the SKIM-SKIS as the issue, it should be shutting down and making the Jeep inoperable within the first 1- 3 seconds, after initially being energized by the key.

It definitely can be the SKIM module, but I am not so sure right now about that?

I am glad to hear you were able to get it running to drive home. Would you mind providing an update when you get it running back to normal? I am interested to find out what your Jeep has going wrong with it.

(edited to add):
I read a story of a very similar problem another guy was having. He followed up to report what was causing the problem. In the thread more than one person told him it might be the Crank sensor... All lights and logic seemed to point at it being the SKIM. He had a P1686 code too. I copied and pasted a piece of his final outcome post below;

(copied and pasted):
Read on edmund forums that the CPS can internally short and cause a backfeed to the PCM and **** all kinds of things up. Pulled the crankshaft position sensor and to my amazement the SKIM light turned off and the fuel gauge came on! Turns out it WAS the CPS, SO GKBID you win!!! Excellent post that I stupidly disregarded thinking that was not the problem. Follow his advice to...
(end of copy and paste)

I am tuned-in..

WMayo

Thank you for all the help! Tomorrow, I hope to drive it home. No windows down (and no a/c), no gauges including speedometer. But just hoping it gets me there, then I can more easily deal with whatever it is.

I may replace the crankcase sensor again, based on what you just posted. Prior to that, I'm of the mind that I have to remove the SKIM, buy a new PCM, and run it without a SKIM - from what I've read, if it doesn't see one initially it doesn't expect to see one. Found where I can get one programmed for my VIN / Mileage for about $200.

However, will try the crankcase sensor 1st, I think. I'll definitely let you know once I get it all solved!

BTW - 1st thing I'm gonna try is the other key I have at home, to eliminate that it may be the key itself.

Noah911

I drove a new Jeep about 3 hours back to where I was staying after buying. I drove without a cluster.. No MPH, RPM, fuel, odo... Nothing worked any on the cluster because of a blown fuse. I drove it for about two hours that way. It is easy to gauge the approximate speed and all. Probably its nice you have someone to follow.

I am a proponent of doing thorough testing prior to replacing anything.

When you have the time to work on it, are you going to try and get it read?

WMayo

Ok, it got me home. Was hot as all get out - no windows down, no A/C (the A/C is a blend door issue). But it got me here.

Now fairly sure I've got either a bus problem or a PCM problem. On the 4 hour trip, gauges would come up periodically, then die again. Sometimes they worked for several minutes, then quit, sometimes they just flicked up and then quit again. Fuel gauge was really flaky, sometimes read full (I had just gassed up), sometimes only 1/2 full.

When I stopped at a store and shut it off, then re-started, the driver's side mirror went hard left and kept trying to keep going - it was clicking. Finally go that to stop, but couldn't adjust it right-left, only up/down. Today it's working ok.

At one point couldn't unlock ANY doors, with FOB or button or manually, other than driver's door with key. I pulled PCM fuse for 5 minutes, then it all started working again.

After I got it home, was done with it for awhile - had to cool off!

Today, thinking maybe window problem was fuse, since NOTHING has fixed them, I checked it - nope, it's ok.

Still getting bus failure on overhead console (hit C/T & Reset buttons, then turn key on) - but if I pull PCM fuse for 5 minutes it passes the test and some things start working again.

Today I'm reading about how everything is on the PCI bus, and ANY problem with it can cause the whole system to go screwy, so am really not positive it's computer but seems pretty likely to me at this point.

Will have my code reader back tomorrow (was borrowed) - it's a much better one than the one I was loaned in Lafayette. Maybe it will tell me something, I dunno. It's driveable, most of the time - today wouldn't even crank until I pulled PCM fuse and reset - but almost afraid to stop anywhere.

If you have any new thoughts, please share! Otherwise I'll update as I check with code reader, etc.

Thank you again!

Noah911

Shoot man that is a lot gone haywire!

You should test the bus system. Check for all up to 32 different ecu's being online... I would do it while the system is most disturbed, because it will allow you easier to be able to find and see the problem.

Try reading pin #2 at the DLC with your DVOM.

WMayo

What's a DLC? Which computer? Don't have a DVOM at the moment, hopefully tomorrow.

Odd thing today - had to run to the store, car started and ran normally. All gauges worked fine, odometer worked, etc. Still nothing picking up on overhead console (fuel mileage, etc). Still no windows.

Same way coming back home.

Went I got home, hooked reader up to it - no codes, said it couldn't communicate. Ran the communication test, sure enough, failed. Pulled PCM fuse and neg terminal for 5 minutes, got comm's working again, re-connected code reader. Says no codes!

Suddenly, my right rear window rolled itself down - it does that from time to time. Tried the other windows, they ALL worked! Gauges still working, everything looks normal except overhead console.

Still convinced I'm looking at a PCM problem. Gotta find something on window controls, though - why would window roll itself down? This has happened several times, but never cause any other issues.

Noah911

By DLC.. I am referring to the Data Link Connector. The spot where you plug in a scanner tool like in the picture above for a WJ.

The PCM is a computer. It is often considered 'the' computer. In reality, it is your 'engines' computer is what it is. It is a main computer, but it is also only one of many computers in your vehicle. Every module is a computer.. The Powertrain Control Module (PCM), Transmission Control Module, Door modules, Body Control Module, ABS Module, Daytime Running Lights Module, etc... They are all computers, or ECU's (Electronic Control Units). There are many different ECU's about 32 different computers in your Jeep. If any one of the ECU's are malfunctioning bad, or have a short, or problem with their wiring (could be a break or open in the wires), they can mess up to cause problems in one or more of the other computers in the system...

If a scanner is not able to communicate for diagnostics at the DLC when it is hooked up, the first thing you need to do is verify that the DLC is recieving the appropriate power where it needs it to do the communicating. It could be the PCM is offline related to a blown PCM fuse is all (as an example)? A way to know if the diagnostics port is recieving the appropriate power is to check and see if your check engine light illuminates for a second after first turning the key. If it does, then your diagnostics is getting the right power where it needs. This means there is another reason.. It could be broken bad pins in the scanner connector, or maybe broken bad terminals on the DLC that does not allow a proper connection to take place?

If not communicating though.. It is likely the PCM is offline the system. Why though? Well, it could be an open or break in the PCI bus wire system (the one single wire that connects all of your vehicles modules to and with the main PCM module.. for systems communication). This PCI bus wire is at pin #2 on your DLC. The no communication with the PCM by the scanner may also be because of a short to/from the wiring going to any module on the system too. Or, it could be because one of the modules is fried. Or, it could be related to a short to any sensor or any other electrical unit in your vehicle that is disturbing the electrical activity happening within the PCI bus and general electrical activity, to not allow the PCM to communicate. Etc...

You can go to the DLC pin #2 to check for normal, abnormal, or no voltage to see what is happening. If it is shorted to ground, to battery voltage, has an open in it, or a faulty module in the system... It will show up here at the DLC in different ways, with different tests giving different readings, depending on what is going on here within the system.

When there is a problem within the PCI bus system, vehicle features may take on a mind of their own. For example, with your window rolling down by itself without input from you using the window up/down control function via the button on your door operated by the door module. It could be a symptom. In fact, the door module may be the problem causing the PCI bus system disturbance, if it is shorted out... You won't really know unless you test by way of the DLC, PCI bus pin #2, and/or using a high end professional data reader tool to force system tests.. to check the proper functioning of all modules and systems in the vehicle.