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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29447
Experience:  GM Grand Master Technician 2007. 14 years experience.
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Chevrolet Silverado: i have a 2004 silverado 2500 hd, with

Customer Question

Hi i have a 2004 silverado 2500 hd, with codes p0101,p0446,p0753,p0758,p2761, i dont worried about the maf code or the evap code, but i would like to know where to start on the other 3 codes
Submitted: 1 year ago.
Category: Chevy
Expert:  GM Tech (Cam) replied 1 year ago.
Hello, I'm Cam.
Can I get your first name please?
Ok so just the transmission codes. Does the transmission shift at all or is it stuck in reverse and 2nd gear only?
Customer: replied 1 year ago.
Alex
Customer: replied 1 year ago.
It wont shift above 50 miles per hour
Customer: replied 1 year ago.
Are you there?
Expert:  GM Tech (Cam) replied 1 year ago.
Ok, Alex, the key is that it does shift. This is the 4L80E transmission,
Does it shift or have all lower gears? Meaning do you get a 1-2, then a 2-3 shift?
Customer: replied 1 year ago.
What i did i clear the codes and test drove it , the 3 trans codes came back , when i drove it it was shifting fine, i went a little over 50 miles per hour
Customer: replied 1 year ago.
I just drove it again and now its not shifting 1-2 or 2-3 brake light came on along with the abs light,
Expert:  GM Tech (Cam) replied 1 year ago.
One moment while I get more information on those codes.
Expert:  GM Tech (Cam) replied 1 year ago.
OK, As I thought. There is a chronic problem on these that actually is very easy to diagnose and fix. The transmission gets power to the pink wire, that power is sent through all the solenoids then the Powertrain Control Module (PCM) operates the transmission by applying the ground to the circuit. The issue is a failing ignition switch. There are 4 main power feeds out of the switch and one, the white wire is dedicated to the transmission. When that contact fails, and it is notorious for failing in this year range of vehicle, you get limited to no shifting, codes like you have.
Expert:  GM Tech (Cam) replied 1 year ago.
Diagnosis can be done either by replacing the switch which is inexpensive or doing this procedure. Pop the tilt lever out and take the lower trim of the column off. With your multimeter set to DC volts, place the red lead on the red wire. With the switch turned on, test the other leads with the black wire. Record the reading and let me know what those are. Repeat the test on the red/white wire. Let me know the results. if the pink, white, brown or orange, white namely have more than 1v, the switch has bad contacts. Attached is a replacement procedure for the switch.
Customer: replied 1 year ago.
Ok let me try this test and ill get back to you soon, thanks
Expert:  GM Tech (Cam) replied 1 year ago.
Myself, knowing these issues I would replace it, and for quality, use an AC delco part. Its not much more than aftermarket and better quality.
Customer: replied 1 year ago.
Hi Cam i just finish installing the ignition switch for the silverado 2500 , clear the codes with my solus ultra snap on scanner , light came right back on with the same 3 codes for the trans.
Expert:  GM Tech (Cam) replied 1 year ago.
Ok, so then we have a wiring issue at the transmission, in the transmission or bad solenoids. Lets start checking the wiring down there and back to the Powertrain Control Module (PCM). Check for places where the wiring may be rubbing.
Customer: replied 1 year ago.
You know weird because when i clear the light before replacing the switch i was able to drive the car for about 5 miles without check engine light coming on but now is different it comes right back on even without driving the car
Customer: replied 1 year ago.
Can the switch installation be the problem?
Expert:  GM Tech (Cam) replied 1 year ago.
Its possible. All of the codes are the same or are there more?
Also is there a remote starter installed?
Customer: replied 1 year ago.
Same three codes, no remote starter but he has some other aftermarket things installed (brakeman compact , kc hilites)
Expert:  GM Tech (Cam) replied 1 year ago.
Take some time to check for anything tied into the transmission or ignition circuits then.
Customer: replied 1 year ago.
Hey cam i checked the power wire going into the trans. With the plug disconected i got no power at that wire, i have a gm guy helping me diagnose the problem , he said to replace the two shift solenoids and flush the syst. , he thinks that wth the plug disconected he is not getting the right readings at that wire , what do you think?
Customer: replied 1 year ago.
P0758,and p2761 keeps coming back
Expert:  GM Tech (Cam) replied 1 year ago.
Power at which wire, the main one to the transmission? Was that disconnected or was a wire inside disconnected?
Customer: replied 1 year ago.
There is a pink wire going to the transmission that is supouse to have power when we check for power at that wire with the plug disconected ,there is no power but ground
Expert:  GM Tech (Cam) replied 1 year ago.
That would do it. That wire gets power from the ignition switch through the IGN fuses. Check those and find why it gets no power.
Customer: replied 1 year ago.
So wven with the plug disconected i should get power at that wire correct?
Expert:  GM Tech (Cam) replied 1 year ago.
Yes, with the key on, that wire provides power into the transmission.