code 24 on 88 blazer 4x4 tranny swap

[Joeglock40]

I just bought a 88 blazer 4x4 k5with a 350 tbi engine. The previous owner installed a new350 and swapped the manual tranny for a 700r4 with a 208 behind it. It runs great but only on the highway it pops the CEL on n off every few minutes. The speedometer is working but I know it's a code 24 the vss. The truck also has a b&m type ratchet shifter. Everything seems to be adjusted right but it won't kick into4th gear until I'm at about 60 mph I'm guessing it had to do with the code 24. So since the Speedo is hooked up n seems to be working, what should I do?? The truck runs n idles good. But it's my first tbi Chevy so this obd1 is new to me. Any ideas???
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[68Timber]

Would the computer have to be changed out or reflashed when you change from 4-speed to 700R4? I don't know anything about VSS or making it work, just asking the dummy question first.

[Jonboy]

On an '87, you should be picking up your VSS signal from the back of the speedo head. 4th should hit somewhere between 35-40 MPH (off of the top of my head). Make sure your TV cable is adjusted correctly. I think you have 2 separate problems. I am pretty sure there will be a different PROM for a manual and automatic trans; the auto version will be trying to lock up the converter. A 700R4 will shift from line pressure at the TV, there isn't an electronic input to make it shift. The electronics for the trans come in for the TCC.

[Joeglock40]

One question.. what's a prom? The guy who did the swap was supposedly a master tech n know his stuff but who knows what he really did.. also if I use the ratchet shifter to manually shift gears the light turns on more n the tranny will kick into 4th at about 45 while the shifter is in 3rd position if I'm just putting around . But when I get on the highway it'll down shift n won't kick into od until 60. .. so adjust the tv cable again first right.. it's supposedly a rebuilt tranny n I don't really wanna burn it up already
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[Joeglock40]

Ok I believe my tv is adjusted right but could having a manual prom vs automatic hurt anything besides throwing the light n irritating me? If so how can I change it? The thing that's weird about the shifting is if i'm shifting manually and have the shifter in 3rd the tranny will kick into 4th at about 45 but if I just keep it in drive it won't kick into 4th till 60ish n if i let off the gas before 60 it'll drop to idle then rev back up to cruise rpm when I give it gas.. maybe the ratchet shifter isn't adjusted right??
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[Joeglock40]

bump any idea??