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Discussion Starter · #1 ·
Hi all. I just picked up a 2006 R/T. The guy sold it because he could not figure out why it keeps throwing codes and going to limp mode, I hope I can figure it out with your help.
When I first looked at it, it had 23 codes. We loaded it on a trailer and got it home. After just running for about 5 minutes, mostly idling, it dropped to 15 codes. I cleared them and drove it 4 miles and now I have 7 codes, mostly "U" codes. It's in the wiring from what I have read in this forum.

My question is: Where are all the grounds that I should clean? I found 3 around the passenger wheel well under the hood. Where else?

Where are all the modules that I need to clean the connections?

This is a great forum. I look forward to contributing once I learn more about my Charger.

Any ideas and suggestions are welcomed and appreciated .

Thanks
 

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Discussion Starter · #2 ·
Update. I just took the Charger out for fuel and some spirited driving. All was well for about 10 miles of city and highway driving until I came up an exit ramp. As I slowed down the bell sounded and the gauges quit and ALL the dash lights came on. Also I had no throttle and no transmission. Coasted to a stop and cut the engine off. I would not restart. The key did nothing.

I disconnected the neg cable on the battery for about 10 minutes and the car started and all the warning lights were off.....for about 15 seconds. They all came back on and the bell sounded and the gauges died again. This time I had throttle but was stuck in 3rd gear. Thankfully I was not far from home.

And my code reader said "link error"

Ideas?
 

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There's lots of "link errors" than can occur. Any specific codes? Communications between the electronic/computer modules is passed on the Controller Area Network (CAN) buses.
There's four buses: CAN-B, CAN-C, diagnostic CAN-C and the LIN (Local Interconnect Network) data bus. CAN-B and the LIN bus operate at a lower speed and provide communication among body and interior modules. CAN-C is exclusively for critical powertrain, anti-lock brake and electronic stability
program functions. The LIN bus is used on a limited basis for the steering wheel switches that control the EVIC. The diagnostic CAN-C bus transmits diagnostic information to the OBD2 port. It allows diagnostic data to be obtained from the other two bus systems without affecting the functions of either.

It sounds like the problem is on the CAN-C bus. There's a FCM (front control module) mounted on the front side of the front fuse (engine bay). The FCM acts as a link between the CAN bus network for critical powertrain, anti-lock brake systems, electronic stability program systems and the network for body and interior modules. The problem could be the FCM or the wiring harness/connectors attached to the FCM. Problem could also be with the PCM (powertrain control module) or the TCM (transmission control module) or the wiring harness/connectors attached to these modules.
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Discussion Starter · #4 ·
Thanks djalbin. I was looking around and under the under hood fuse box and noticed a white wire with a blue tracer that was cut. I didn't have time to fix it this evening but I will in the morning. The wire goes into the FCM. It would be so cool if fixing that one wire was all it needed.
 

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Discussion Starter · #5 ·
Fixed the cut wire but it changed nothing. Still lighting all the warning lights and the gauges quit, except for the fuel gauge. The previous owner said he replaced the alternator, fuse box and the battery. I'm still researching online. I'll update if I find it.

Oh, when all this happens my scan tool won't work. It says "link error" If I disconnect the battery for about 10 minutes, it will work normally. The disconnect resets the system.
 

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Each CAN Bus is two wires twisted together (twisted pair bus). The CAN-C diagnostic bus is a twisted pair of wires colored as white/light-blue tracer and white/dark-blue tracer. The white/light blue tracer wire is the (+) signal wire and the white/dark-blue tracer wire is the (--) signal wire. The CAN Buses are low voltage & low impedance (120 Ω), so any repairs to the wires need to be done without introducing any added resistance.

There is a CAN-C diagnostic bus link between the OBD2 port and the FSM. The link error message you're getting with the scanner is an error message indicating it can not communicate on the diagnostic bus.

Since the previous owner replaced the front fuse box I would also check the wiring harness/connectors in the fuse box as well as to the FSM.
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Discussion Starter · #7 ·
I probably added resistance by using a crimp connector and plugging a pin of the connector in to the back of the fcm connector. I guess I should take the fcm connector apart and replace the pin. The wire was cut right at the fcm connector leaving no wire available to splice.

Today I removed every connection from the ecm, fcm, tcm and the fuse box. Inspected every pin, cleaned everything with electronics spray, put dielectric grease all over, and put it back together. I was rewarded with a whole new set of problems. The engine runs for 2 seconds and quits. It did this about 5 times and now it won't start at all. I disconnected the battery again and quit for the day. A friend says I put too much dielectric grease on and I should clean it again and leave the grease out.
 

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Discussion Starter · #8 ·
Update

I cleaned all the dielectric grease from the connectors and reconnected everything. Still had the anti-theft active so I put the key in the ignition and pulled the #1 fuse for about 10 seconds. Now the car will run but after about a minute, all the warning lights come on and the gauges quit except for the fuel gauge. I have disconnected the neg battery cable overnight and I still have this condition the next day. I have purchased a used under hood fuse box and will try that today but I doubt it will help because this box looks very weathered and faded and the previous owner said he replaced the box before he gave up.
 

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Some of the inputs to the instrument panel are hard wired, but most are in the form of electronic messages that are transmitted by other electronic modules over the Controller Area Network (CAN) data bus. You can run the instrument cluster actuator test & if it passes you will know the problem is with the CAN bus messages.

1. Begin the test with the ignition switch in the Off position.
2. Depress the odometer/trip odometer switch button.
3. While still holding the odometer/trip odometer switch button depressed, turn the ignition switch to the On position, but do not start the engine.
4. Release the odometer/trip odometer switch button.
5. The instrument cluster will simultaneously begin to illuminate all of the operational segments in both VFD units, and perform a bulb check of each operational LED indicator. The VFD segments and LED indicators remain illuminated as each gauge needle is swept to several calibration points and back. If a VFD segment or an LED indicator fails to illuminate, or if a gauge needle fails to sweep through the calibration points and back during this test, the instrument cluster faulty.
6. The actuator test is now completed. The instrument cluster will automatically exit the self-diagnostic mode and return to normal operation at the completion of the test.
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Discussion Starter · #10 ·
Update.

It was the BCM body control module. I sent the module off to Module Experts and they said it cannot be fixed and I need a reman one for $499. I did a google search on them and found that they say this to everyone who sends them a module. It's a scam. I called my local dealership and they sell a brand new one for $199. Plus $139 to program. It fixed the limp home problem but the CEL remains on because I foolishly tried the ASD jumper wire thing and it blew the O2 sensor heaters. I will start a new thread to ask about that problem.

Thanks all.
 

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The BCM performs the functions that are also on the FCM (front control module). Whether your car has a BCM or a FCM depends on the model year. I don't remember which year they switched from a FCM to the BCM. At least you found the problem.
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