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P0744 code on 2005 Quest
Joined the forum and was really glad to be able to d/l the engine performance manual so I could diagnose the troubles on a 2005 Quest with the 4 speed automatic transmission. Turned out all the sensors were good, the issue was two wires that were burnt in the harness that feed the intake air temp signal from the MAF sensor to the computer box.
Now that those problems are fixed, the Quest runs great, but getting on the freeway is another issue. It shifts fine into second gear, but then tries for third and it surges a few before dropping back into second gear. The CEL came back on too - P0744 torque converter control. Spoke with a good friend at a transmission shop who stated to me that six out of eight Quests which came in for transmission rebuilds turned out to be wiring issues and/or bad computers. Only two actually needed transmissions and both of those were pushing 280K miles plus. The Quest I have is at 144K miles. So the question I have is can someone post the code P0744 diagnostic flow chart so I can check the wiring related to the transmission? |
#2
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What you need is the Automatic Transmission manual (A/T). If you've d/l a manual then you know where it is. If it is not available for your model year, you can go back two years or forward two years as it should be similar. Or you can request from Administrator. There may be a fee involve which is less than what you pay for after market manuals like Haynes.
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#3
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You might try Nico Club's website. They have full factory service manual downloads at their site and "may" have one for your Quest.
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#4
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You were correct, the Nico Club site had it. Thank you very much. An eleven page diagnosis chart! Got my work cut out for me now!
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#5
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Well, it's been a while, but the Quest drives perfectly as of yesterday. Thanks to the manual being at Nico, and being directed to it from here, I learned the code specifically states that the most likely cause was mechanical failure in the trans. Boy was that spot on. First I noted line pressure would spike, then fade right down. That prompted a pan-pull to do a solenoid check. It's tight to get out, had to take top trans mount bolt out and then I got a 7/8 socket between the case and subframe. Just enough room to remove the trans pan. Both magnets were loaded up big time with metal filings. To remove the solenoids, the valve body had to come out. Three out of five solenoids would not even click when I applied 12V, one hummed/buzzed. Of the two that clicked, neither would seal when activated.
With the valve body out, you can see one of the clutch packs and I pushed on the discs and they moved around with a lot of slop. No way a clutch pack should have that much clearance! I could make the discs rattle! Then, looking at the removed valve body, there is a lot of grit on the upper surfaces. At that point I figure there were multiple stuck or sticking valves that caused the solenoids to burn out. Soooo, knowing a rebuild trans was over 3k, I searched and found a 77K miles trans a little over an hour away. That meant the subframe got to come down, engine and all! Yaaaaa! Actually a pretty smooth job except for the steering coupler at the rack, which was rusted solid. Can't forget to take the bottom 4 bell bolts and torque converter bolts out before dropping the frame on 4 jackstands. With the body up and out of the way, the trans swapped over in about 35 minutes, do the 4 bell bolts and torque converter when back up again. Test drive was sweet, with all four forward gears again. Again, thanks to the members of the forum for help in gettin 'er dun! |
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2005, code, p0744, quest |
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