Hello alex, You said " Key conditions I described like e.g. "cold engine" would probably eliminate conditions 4) and 5) or I cannot understand how PCM or hydraulic control can be affected by a cold engine?" O.K. One way a cold engine or lets say, "cold oil" can effect hydraulic controls is, cold oil is thicker oil and "old" cold oil is sticky. This can and does cause things to stick or work slow enough to seem inoperative (in the cold). Now if this was my car I would start by checking for loose or broken wires, at or going to any controls to the transmission. Also if you live in the north, Ice and road salt can corrode wire ends inside plugs. This is one way cold can effect your PCM or TCM is these plugs and or connections at these Control Mods. These controls need to have dielectric grease on the contact ends of the plugs. As this grease gets old it looses its ability to transmit electrical signals. Old grease turns orange to yellow, new grease is kind of a milky clear. The old grease is worse than no grease. So, check any wires / plugs to the transmission, looking for broken wires / corroded ends in the plugs. Clean the plugs of any old grease / dirt / corrosion. You may have a bad Shift solenoid valve or you need to change the transmission fluid and filter. This would be my first steps to fixing your problem. Check this and repost if you find all is well with your wiring and trans. fluid.
Diagnostic Trouble Codes (DTC's) NEVER tell you what part to replace. They only indicate which sub-system within the engine/transmission management system is malfunctioning. Diagnosis must be performed to pinpoint the cause of the failure. Allmost all DTCs have multiple possible causes. It is the job of a trained technician to perform the steps required to properly diagnose the system and give you the definitive answer you are lookig for.
One other little piece of advise. You will be money ahead to take your car to an independant shop that specializes in transmission repair. The dealer does not see very many transmission problems because they usually do not occur until the vehicle is way out of warranty. I have dealt with that particular code in the past and it turned out to be a bad shift solenoid in the transmission, however, the transmission clutches were trashed as a result of the faulty solenoid.
Temperature causes expansion and contraction. All electrical circuit are subject to failure due to cold or hot conditions. Circuit boards in conrol modules commonly flex due to temperature and can cause intermittant failures - I replace control modules all the time for this reason. The solenoids inside your transmission could be experiencing a shot circuit or an open circuit due to the cold conditions you are describing. One does not know exatly what is causing the code until testing is performed. The only way to eliminate an electrical problem is to perform electrical testing on the circuit that is failing. To eliminate the possibility of a mechanical problem in the hydraulic control assembly, pressure testing must be done to see if the pressures are out of range under certain conditions. If the pressures are incorrect, it also has to be eliminated that the solenoids are notthe cause of the pressure problem before replacing the valve body. The valve body itself can also have an intermittent problem due to temperature causing one of the spool valves to stick inside their bores under certain temperature ranges.
The conditions you describedwill be helpful to someone performing the testing however. Many times I have tested a system with an intermittent problem and found nothing wrong with the system. This will let the technician know that the testing must be done while the system is cold in order to locate the failure.
The "Experts" that built the car are telling us in the service manual to run the tests to eliminate the possibilities that you listed. They are telling us to do that because THEY can't narrow it down any further than that without testing. How could you expect anyone else to do it over the internet without testing the system?
The "Experts" that BUILT the car are telling us in the sevice manual to perform tests to eliminate the possibilities that you listed. They are telling us to do that because THEY can't narrow it down any further than that without testing. How then, can you expect someone over the internet to do what they can't do.
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I did not mean that the OBD code tell what exactly need to be replaced. I've posted lots of details which I think should be enough for expert to narrow down the possible problem cases to one or 2 at the most. Looking at the possible options:
1) Shift solenoid valve 'B' is damaged or failed
2) Clutch pressure control solenoid valve 'A' is damaged or failed
3) Clutch pressure control solenoid valve 'B' is damaged or failed
4) A/T hydraulic control system mechanical problem
5) TCM or PCM has failed
I'm not a car expert therefore looking for ones. Key conditions I described like e.g. "cold engine" would probably eliminate conditions 4) and 5) or I cannor understand how PCM or hydraulic control can be affected by a cold engine?..
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