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The purpose of an Automatic Transmission is similar to that of a manual transmission, the auto tranny's primary duty is to allow the engine to operate in its narrow range of speeds while providing a wide range of output speeds.
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DTC's 0452 & 0502

November 20th 2009, 6:42pm

:chevy: My van has 200k+ miles. It's been a great van and I plan to keep it that way. It's been telling me it wants my attention lately by jumping back and forth between 1st & 2nd then 2nd & 3rd while accelerating. The speedo needle will jump from zero to much faster than I'm actually going and eventually(15 seconds or so) level out as will the trans shifting. Also, the Anti-lock light turns on & off during this shifting process and occasionally stays on .
I had a similar problem two or three years ago and I replaced the the shift valves inside the tranny, of course along with the filter and fluid.
Symptomatically, if my memory serves me correctly :lol: , it seems like the same problem, though I don't remember the anti-lock light coming on.
I will confess and say I have not changed the fluid & filter since the valve change(maybe 25k mi.) and as I recall, I purchased the valves from AutoZone. :doh:
So, brow-beat me :whack: , then please give me your experienced opinion/advice in diagnosing this issue.
The only codes are P0452....Evaporative Emission Control System Pressure Sensor Low Input and P0502....Vehicle Speed Sensor Circuit Low Input.
Questions are welcomed and input in greatly appreciated. :bow:

I bought this van in 2005 with 140K mi. and have drove the poop out of it. Servicing the oil & filters regularly, replacing plugs, cap button and wires twice(last time, less than two months ago, belts, hoses as needed(before they failed).
I cannot believe how awesome this van has been. My dad has had three older(pre-vortec)two with over 200k and one with over 300k and only quit driving it because he wrecked it. :crying:
Yes, I'm a newbie to the forum, though I have been reading it for a couple years and have had success with diagnosing minor issues through reading the post.
So I thank you all for posting and I look forward to being a part of this awesome community.
Peace, C-man

Re: DTC's 0452 & 0502

November 29th 2009, 3:42pm

I would seriously consider replacing the speed sensor and checking the wiring carefully for corrosion. The speed sensor input is used for alot of things, including shifting, abs, and the speedo.

Re: DTC's 0452 & 0502

November 29th 2009, 4:04pm

I agree on testing the speed sensor!
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