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Discussion Starter #1
Mine is the '05 R/T. I have the common stalling issue which mine starts about 15 minutes after start up. It will usually start right back up, and can do it at idle, high idle or driving. The transmission shifts very harsh, up or down. I also have the usual ABS lights and its friends shining brightly on my dash. At the moment, I have the following codes: U0100, U0164, U0110B, U0155 and ABS codes U140b, U1409. I found evidence of a used PCM (salvage yard markings). I found burned grounds on the engine harness on the rear of each head. I removed the engine harness and found this ground simply crosses from one head to the other. I also haven't found any evidence that this ground melted into any of the other wiring enough to make possible contact. This dashed my hopes of a simple solution pretty quick. I also found one of the cam sensor wires had been bypassed between the sensor and PCM plug. One thing that this one did was throwing cam and crank sensor codes, which I replaced both. Those codes (cam was intermittent) went away when I replaced the sensors.


Since this is a communication problem, which from the looks of reading other posts, could be about anything in the computer or ground system, I could use a little help to help check things before throwing money and parts at it. I still have the engine harness off the vehicle and am going to ohm things out. One question is about the pairs of wires twisted together. Are those the bus lines? If so, what should I see on those with the key on? Would that be the 5v reference? Any help appreciated.
 

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U0100 - LOST COMMUNICATION WITH ECM/PCM
U0164 - LOST COMMUNICATION WITH HVAC CONTROL MODULE
U0155 - LOST COMMUNICATION WITH CLUSTER/CCN
(instrument cluster, Cab Compartment Node or BCM body control module)
U140B - IMPLAUSIBLE LEFT REAR WHEEL SPEED SIGNAL RECEIVED
U1409 - IMPLAUSIBLE LEFT FRONT WHEEL SPEED SIGNAL RECEIVED


As you have already determined there's lots of communications codes being logged and the wiring harness has issues. The main communications modules include the PCM, TCM and BCM/FCM.

PCM = powertrain control module
TCM = transmission control module
BCM = body control module
FCM = front control module


I don't know if the 2005 has a BCM or a FCM. The FCM is mounted on the front side of the engine bay fuse box. The BCM is mounted under the instrument panel (my 2012 has the BCM on the passenger side).


The CAN bus (Controller Area Network) is a twisted pair. CAN-B operates at a lower speed than CAN-C and provides communication among body and interior modules. CAN-C is for critical powertrain, anti-lock brake and electronic stability functions.


All nodes are connected to each other through a two wire bus. The wires are a twisted pair with a 120 Ω (nominal) impedance.The CAN bus must be terminated. The termination resistors are needed to suppress reflections as well as return the bus to its idle state. High speed CAN uses a 120 Ω resistor at each end of a linear bus. Low speed CAN uses resistors at each node. Signals across the bus are "0" and "1". Signaling drives the CAN high wire towards 5 V and the CAN low wire towards 0; with the differential voltage at a nominal 2 V.



The other wires on the CAN bus are power & ground. A typical CAN bus connector will have four wires or pins:

CAN-Low (CAN−)
GND (Ground)
CAN-High (CAN+)
CAN V+ (Power)

You can check the physical connections/wires but you need a CAN bus analyzer to see what messages are being transmitted over the CAN bus.
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Discussion Starter #3 (Edited)
Mine has the module on the fuse box in front. I have found the twisted wires in the harness. I found a set of 4 twisted. Voltage wise, what should I see on the CAN V+? I am assuming ground is ground and I should be able to check it to the chassis. On the can data wires, should I be able to check at the PCM plug across those and read 120 ohms? Is that disconnected or connected? I do have a PDF shop manual, but there are so many pages that I really don't even know where to start my search for tracking things out. I assume I can check the CAN V+ at each module? Do you by chance have any idea about what frequency the CAN C bus runs at?

From what I am reading here, it looks like this is pointing to a bad PCM or wiring. It seems there is quite some problems with that part. The HVAC is working (seemingly ok), gauges are working, trans responds to manual shifting or auto, although very abrupt. I did replace the wheel sensors on the left side, but didn't clear the codes. I just don't want to replace the PCM only to have the exact same problems. I found the ground problems when cleaning and checking the connections. I am very inclined to run a new and specific ground from the battery to the engine block, then a good jumper from the engine to the strut tower.

Thanks so much for your time and information on this!
 

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The only diagnostic procedures I have seen for CAN Bus issues has been the Network Diagnostics that are included with the advanced diagnostic systems (e.g. dealerships, collision centers, etc ...).
The PCM cannot determine a poor system ground so ensuring you have good system grounds is a good idea. Inspecting the PCM pins, connector/wiring is a good idea but probing the PCM pins or PCM harness connectors can damage the PCM circuitry ... so it's not recommended. The dealership attaches a Miller Special Tool #8815 (PCM pinout box) when they need to measure/probe the signals.
https://www.ebay.com/itm/MILLER-SPECIAL-TOOL-8815-PCM-DIAGNOSTIC-PINOUT-BOX-ADAPTER-TOOL/143068507093?epid=660925523&hash=item214f8c2bd5:g:IXAAAOSwzgtcJPPO:rk:2:pf:1&frcectupt=true
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Discussion Starter #5
I got into the engine harness more today, but haven't really found anything for sure. I opened up a taped up area and found some repairs had been made. I opened up one of the splices and saw that it had been soldered and shrink wrapped. This part of the harness went near the exhaust manifold. Wires stuck together, but I didn't see any evidence of melting to the point of shorting. Great. Same where the ground had burned up. Nothing. I traced the twisted wires in the engine harness to both knock sensors. There is a set of 3 green wires that are twisted together, running down both injector/coil harnesses. I traced one to the throttle body, but think I am wasting my time on more. So, it looks like this could be contributing to possible sensor issues, but not the communication problems. I am going to check all the splices and check the harness where it would move between the engine and shock tower. Probably tape back up and put back on. Then re-do the grounds and see what I get. I'm not holding my breath...

It sounds to me like the data and reference wires would run between the different modules. If I can find the reference wire then at least I could check that. The PCM may be junk and from reading here it doesn't sound like I can grab one from another car and try it.
 

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The color mapping of the wires may change from MY to MY (model year) but the CAN Bus wires for a 2005 are probably as follows ...


CAN-B twisted pair: white and white/orange
White is for CAN (-) signal and white/orange for CAN (+) signal
CAN-C twisted pair: white/light blue and white/light green

White/light blue is for CAN (-) signal and white/light green for CAN (+) signal


The exception for the CAN-C twisted pair is the CAN-C diagnostic signals connected to the Front Control Module.

CAN-C twisted pair: white/light blue and white/dark blue

White/light blue is CAN Diagnostic (+) signal and white/dark blue is CAN Diagnostic (-) signal.
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Discussion Starter #8
So far, I repaired what damage I could see with the engine harness. It basically was some melted wires, but none were touching metal to metal. The ground between the heads was burned. I removed it and ran a battery cable between the heads and to the strut tower. I cleaned all the grounds that I could see, ran a 1-O cable from the neg of the battery to the engine block, heads, starter and chassis. I still have the original ground from the battery to the chassis in the rear.

Results? Well, the starter spins a lot stronger, and it doesnt seem to stall as of yet. New problem? Yep, now the trans stays in low gear and wont shift. I got a new speed sensor code, in addition to all the codes listed above. So, I ordered a computer from Car Computer Exchange, based on reviews. I have not plugged it in yet since the instructions say that if there is a fault that damages it that it will void the warranty. I called to ask the results of the test on my core and got basically a "drop dead, we aren't going to test your core until we need it" speech. Nice... Any thoughts or advice before I move forward? I thought of paying whatever shipping etc to return the computer and request my core rebuilt and sent back with the results.

Thanks in advance,

Tim
 

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now the trans stays in low gear and wont shift.
There's a TCM (transmission control module) in addition to the PCM/ECU. Several possibilities for staying in low gear (1st gear?). Could be Limp-In (limp home) mode, communication between the TCM and the shift lever assembly (SLA) or internal transmission issues. There's sensors in the SLA and the transmission. Which speed sensor code is getting logged?
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I want to say it is the RR. It's a new code. I suspect it is limp mode. It will run 22mph and buck and carry on like it isnt getting enough fuel. I suspect governor. It wont rev over 3k, in gear. I havent plugged the new PCM in yet. I read elsewhere that a failing alternator can cause a lot of grief. I can replace the TCM and PCM at the same time and see what I get. I just wish I could get a report from CCE before I connect, but I guess thats too much trouble. Oh, and the brake light comes on after I drive it a few feet in addition to all the other lights.Plenty of fluid. This too is new. Oh, I forgot to mention the airbag light comes and goes now.
 

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I suspect governor.
There isn't a governor. The maximum speed of the car is controlled by the PCM (electronic speed limiter). The bucking could be a fuel supply problem (eg. fuel pump, fuel pressure regulator) or the electronic fuel injection system. The PCM controls the fuel injectors and the pulse-width/timing for fuel to each cylinder. This is dependent on signals from several sensors (e.g. camshaft position sensor, crankshaft position sensor, throttle position sensor, MAP sensor, etc...). Since you're having so many problems, from so many different systems, I would suspect there's a basic/underlying problem with the wiring harness/connections. Could be insufficient ground connections, bus communication signals, sensor signals, voltage supply, etc... A good battery and alternator are needed. The PCM provides the +5V supply to the sensors and regulates alternator voltage to the battery.
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Discussion Starter #13
Thanks, needless to say I am quite frustrated with this car. I had it over 2 years and only been able to make one trip in town and a few rounds around the block. I do have a new battery in the car, new cables, grounds cleaned and extra grounds run to the engine from the battery. It sat for 6 months without a battery connected while I ran the new grounds cables. All the codes mentioned above returned. The trans shifted before I made the changes. Note* I also had the engine harness off making repairs.*. The trans shifted harshly tho. Now, I am sure it's in limp mode, new speed sensor code and brake light coming on after its been driven a few hundred feet. The last 2 are new. So, now I sit with a rebuilt computer on my bench trying to decide if I should plug it in or not. Ill double check connections and all. I may put a new alternator on it to make sure that thing isnt spiking things. I think there are too many communication codes to have all those seperate problems. Unless the car has been flooded lol! I am really open for suggestions now. I either need to get this running or sell for parts.
 

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I think there are too many communication codes to have all those separate problems.
It's tough to diagnose the communication (CAN Bus) problems without a CAN Bus analyzer.
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Sounds like you fixed a lot of potential issues along the way, but have you tried cleaning and firmly reseating the connectors to the PCM?
 
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