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Discussion Starter · #1 ·
Howdy everyone! 2014 Limited with the diesel with 62,000 miles. I bought it new with 26 miles on it.

Camping this past week up at Rangeley Lake State Park, coming back from hiking one of the local mountains and then it hit...dashboard lit up like a Christmas tree. First the Check Engine Light (Malfunction light) came on for no reason, out of the blue, followed several minutes later by the "service 4wd light" and "service electronic throttle control". Jeep went right into what I would call a "limp mode". Coolant temperature gauge went all the way cold (engine was warm, normal operating temperature), radiator fan was roaring on a higher speed than I have ever heard (alot louder vs when A/C is on), idle fell down to about 500 rpm and sputtered, felt like it was going to die. No throttle response, Yugo-like acceleration. Had to use the paddle shifters to shift up gears.

I am out in the sticks, far away from a city.

I pop the hood, take the engine cover off and begin to troubleshoot. Top radiator hose is hot. Housing that holds the thermostat is hot. Bottom radiator hose from the block is hot, to the point where the connector hose to the expansion tank, then goes cold. WTF. I think stuck thermostat or a partially operating thermostat.

I was thinking to myself..there is no way I can tow my 5500lb camper up mountains in this state.

I disconnect the negative terminal from the battery (AGM type for those who didn't know>>>big bucks!) for about 10 minutes. Reconnect, fire it back up...and the Jeep acts stupid again.

I open up the expansion tank, let that bleed off the pressure, grab the lower radiator hose and begin to squeeze it rapidly...my thoughts were to try to move the coolant thru the block and/or up to the thermostat.

It seemed to work, because it got rid of the codes, with the exception of the CEL. Coolant temperature was normal (just past what I would call the 1/4 mark). Make it back to camp. Jeep is left off till next morning.

Driving (without camper), temp gauge slowly comes up, and right before it hits that 1/4 mark, boom, dash board lights up again with those two faults.

I go thru the same troubleshooting steps and get out of it. I call the dealer and tell them what is going on and that they can expect me in the next day or so...if I can make it home.

At the dealership, talking with the service manager and the lead foreman....they never heard of this or seen this issue. Great. Figure it out I told them. I told them I thought it was a thermostat issue.

Two days at the shop pass. "Thermostat Rationality" is what they told me. Need a new housing/thermostat (can't just change a thermostat these days anymore) and a thermocouple that attaches to the unit.

I asked them how and why did it trigger my "service 4wd" warning. They didnt know...PCM threw off a bunch of codes. This is the printout of the codes that they recovered:
ABS B1783-01 Stop Lamp Control General
ABS U0401-00 Implausible Data Received from ECM/PCM. What the hell does that mean?
ABS U0403-00 Implausible Data Received from Transfer Case. Huh?
DDM B1D4A-2A Memory Switch Input Stuck
DDM B2860-15 Door Ambient Light Control Circuit short to Battery or Open
DTCM U0401-00 Implausible Data received from ECM/PCM
HVAC U0184-00 Lost communication with radio.
PCM P0118-00 Engine coolant temperature sensor 1 Circuit high.
PCM P0128-00 Thermostat Rationality
PDM B2860-15 Door Ambient Light Control Circuit short to battery or open.
PLGM U0422-00 Implausible Data Received from body control module.

Cool huh?

Dealer replaced that thermostat unit and temperature sensor. Glad I paid for the extended warranty. Look up that part on the NAPA web page and you can see the price on that sucker.

Once my Jeep hit 60,000 miles, it's reliability has started to deteriorate.

Anybody else have similar issues? I am beginning to look at getting a truck again to replace the Jeep.

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