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Discussion Starter · #1 ·
hi, im driving an 02 chev 3/4 ton 2wd all stock. started having shift problems today. tech II code was po733 incorrect 3rd gear ratio. thinkin its the nsbu switch and need to know what the napa part number for this is also what code p0733 is? thanks for your help
 

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A P0733- Incorrect 3rd Gear Ratio sets when the transmission sees slippage in the clutches after 3rd range is attained. Basically either your C1 or C3 clutch slipped while driving.

I doubt it's the NSBU because I've never see a bad one of those set a gear ratio code. I'd suggest checking the basics: Is you fluid level good (should be at or near Hot Full at 150 to 180F) and when is the last time you chnaged the spin on filter?

When you check the fluid see if it's dark or has a burnt smell to it. This may indicate you're slipping clutches.
 

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Discussion Starter · #3 ·
replaced the nsbu switch and had to clear the codes with tech II problem fixed and seems to be shifting and running normal
 

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Discussion Starter · #7 ·
me too, ive got several codes that it showed the second time we ran them. i'll list them here tommorrow what does a good rebuild cost??? and hey i thought the allison was unbreakable haha thanks for your time
 

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We are just finishing replacing our 2nd trans on 2 different trucks last week at the dealer, same code...burnt, nbsu can't cause that code....
 
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