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Discussion Starter · #1 ·
I own a 2009 Challenger RT with only 21K miles. It was bought new, so it's a garage princess these many years. This past weekend I took it out to a local car show, and on the way back home, it shudder and went into some sort of limp mode. After getting home, I put a scanner on it. The code (U0101) is saying communication was loss in the TCM. I googled the issue, and many experiencing the same problem made suggestions I tried them, but to no success. I had it towed to my local repair shop because the engine light, and traction control lights stayed lit. I am still waiting on a diagnosis and repair cost. I am guessing that the issue lies at the rear end since the traction lights are constant. I attempted to clear the code, but to no avail. Any ideas?
 

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The Bacon Hauler (‘12 Cop Charger)
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Traction light can be something like one of the ABS sensors going/gone bad, but with the presence of the TCM communication code, I’d say it is a result of that possibly.

The TCM communication code could be lots of things. The TCM is behind the knee bolster, under the steering wheel. You can pull that bolster and check the wiring going to the TCM, there are two horizontal wiring harness plugs. Make sure they are seated securely into the module.

The wiring harness enters the transmission through a large round plug on the transmission’s forward passenger side, just above the pan (assuming this a 5 speed auto/NAG1). I have heard about that plug’s seal leaking and allowing trans fluid to wick up into its wiring harness and causing problems.

Has the transmission ever been serviced, had the fluid/filter changed, etc?

If not, it might be worth it to do that now and check the condition of that plug I mentioned for any signs of leakage into the wiring harness.
 
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2015 RT 5.7 M6
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Could be an issue with the can bus or you don't have enough voltage (how old is the battery?). Go to the online chiltons manual in the link below and enter the code you are getting in the repair section. It will give you steps to diagnose what is causing the problem. That is if the shop can't figure it out.

For example, you will get a list of possible causes which you work through to hopefully get to your problem.
Possible Causes
CAN B OR CAN C BUS CIRCUITS OPEN OR SHORTED
DTCS RELATED TO BATTERY VOLTAGE, IGNITION, OR VIN MESSAGES
TIPM NOT CONFIGURED CORRECTLY
TRANSMISSION CONTROL MODULE
TCM POWER AND GROUND
MODULE THAT SET THIS DTC
Diagnostic Test

VERIFY DIAGNOSTIC TROUBLE CODE (DTC) IS ACTIVE

NOTE
Make sure the IOD fuse is installed and battery voltage is between 10 and 16 volts before proceeding.
 

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2011 SXT Built in the Canada Plant
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USUALLY its the Wheel Speed Sensor get Autozone, O'Rillyes. Advanced to scan the car and find out which one and get it repalced there is 4 on the car a ODBII will tell you which one.
 

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Unless there are other DTCs U0101 specifically calls out loss of communication with TCM.
1018531


Although one of the possible causes is related to a bad ABS module. First check that the system voltage is good as that can cause all sorts of problems. If the battery is +6 years old then replace but there are so many folks that state the vehicle won't start or has all sorts of problems once the battery is disconnected on pre-2015 models. So I would connect a 12V source to the jumper posts and then remove the battery.
 

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The Bacon Hauler (‘12 Cop Charger)
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Unless there are other DTCs U0101 specifically calls out loss of communication with TCM.
View attachment 1018531

Although one of the possible causes is related to a bad ABS module. First check that the system voltage is good as that can cause all sorts of problems. If the battery is +6 years old then replace but there are so many folks that state the vehicle won't start or has all sorts of problems once the battery is disconnected on pre-2015 models. So I would connect a 12V source to the jumper posts and then remove the battery.
That screen shot of the manual text appears to have a type in it...at least I hope it does, or the folks that wrote the code to control the PCM have one hell of an infinite loop possibility in their code. 🧐
 

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The Bacon Hauler (‘12 Cop Charger)
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Definitely maybe!
My reply pointing out a typo contained a typo itself...what’s going on? I’m light head-headed...difficulty...breathing...who...where...mom?
 
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Discussion Starter · #9 ·
Hi all. Thanks for all the suggestions and advice. I had the Chally towed to my neighbor's repair shop (neighbor owns it), and they discovered it was the Multi function relay, a $23.00 part + labor. Total cost, less than $145.00. Car seems to be operating fine now. I will take Nuke's advice and purchase a new battery. The one currently in the vehicle is over ten years old, but still functioning.
 

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The Bacon Hauler (‘12 Cop Charger)
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But I was thinking it!
 
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2016 SXT Plus Blacktop
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Where do you think the technology came from? :censored:

A Guy
 
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