Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
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I will do my best to assist you. When you are finished please click on accept only if you are satisfied. I don't get paid unless you do.Please do not accept if you cannot leave positive feedback. I don't know if you are a tech or a just working on your own vehicle so we may have to fine tune the answer. I only know as much about your problem as you have told me in your post, so my answers will be based on what you tell me so please add all the details you can.
What is the colour and condition of the transmission fluid/
OK - my Check Engine light came on and a mechanic detected an 1811 code which is related to the transmission. I told my son to take it to AAMCO and they called me and said it was the EPC solenoid and possibly the catalytic converter. I had the cat changed about 5,000 miles ago when there were about 91,000 miles on the car. At about 75,000 miles I had the transmission flushed (which I think was a big mistake) Sometimes pulling out from a light the car would jump like the transmission was shifting abruptly or didn't down shift all the way and then did when I hit the gas. Anyhow when I told AAMCO that the cat had been replaced they kind of backed down on that. They are saying that to replace th EPC would cost $525. Your thoughts?
That code is for maximum shift adapts. T
what that means is the transmission cannot adjust the shift timing anymore.
I doubt the solenoid because it would whine and shift hard but would not set a code.
MY thoughts are that you have a cut seal or some other issue in the transmission.
if that is the case, why would AAMCO say that the 1811 is the EPC ? Don't they know what they're doing?
They mean the pressure control solenoid?
Because it is a common issue.
they said EPC which they say is the Electronic Pressure Control solenoid
ya, there is no code for that.
The transmission pressure is modified by an adaptive modifier which controls the shift execution time. This diagnostic tests the time required to accomplish the shift. If the shift takes longer than 0.65 seconds and the adaptive modifier cannot shorten this time, then a counter increases by one.
If the PCM detects a counter value of 2 during one trip, then DTC P1811 sets. DTC P1811 is a type C DTC.
Well my local Chevy dealer says the ther is a P1811 code
There is a P1811 but it is not for the solenoid they say.
ok - what is a type C DTC?
It means that it takes a bit to set, 2 cycles to set
so what it the P1811 code for?
It is the code that sets when the transmission has reached the max shift adapt.
Code P1811 is hands down the most common trouble code and commonly asked about problem. This code can set for numorous reasons and often by a failing pressure control, BUT on higher mileage transmissions this is often not the case or at least is not the only cause to the problem. With that said it is important to understand that replacing the pressure control solenoid is NOT a guaranteed fix!This code will set when the pcm/tcm detects excessively long shift times. For every shift the pcm/tcm watches how long the shift takes to complete in milliseconds. If the shift times are over roughly the .06 second timeframe and the pcm/tcm tries to compensate for this by raising line pressure and still does not see acceptable shift times after a few shift cycle it will trigger code P1811. When this happens it puts the transmission in a max line pressure condition to help protect the transmission against excessive slippage and burnt clutches. While this condition is present you will feel harsh shifts, some vehicles more agressive than others, and you will also hear a whine noise similar to what a power steering pump that is low on fluid will sound like. You can shut the engine off for a brief moment and restart the vehicle and it will feel normal again until a few shift cycles of excessive shift times and the cycle will repeat itself. This typically only happens after you have driven for a short while and the transmission and its fluid warms up.Some common causes to this problem are--Poor working PCS (Pressure Control Solenoid), also called EPC or Force Motor -Excessive clutch clearances-Poor functioning accumulator system-Worn internal seals and sealing rings-Excessive valve body wear-Dirty MAF sensor resulting in lower commanded line pressure
Those may be but I have yet to be something outside of the transmission.
I don't understand - "yet to be something outside of the transmission"
But you did not answer my question, what is is the colour and condition of the transmission fluid?
Every time I see this code, it is internal transmission issues.
I don't know - I am 6 hours away from where the car is
OK - so if they replace the EPC and the hard shifting contiues will it be OK for my son to drive the car 6 hours home where I can get it to a transmission repair center - will this do any damage or will it let him down?
Hard shifting is better than soft, because hard means it is set to max pressure, which causes the hard shift. The solenoid is the pain to change, it requires removing most of the transmission to change it.
So will it be OK to drive 6 hours?
While it is really hard to say yes or no, I believe it will be.
OK - I've gotta go. Thanks,