How do I adjust the throttle linkage to make the transmission shift properly

Question

I have a 1991 Chevy pickup C1500, I just put a new transmission in it. I find that it won't shift until I hit about 40 mph. I was told it was probably the throttle linkage. How do you adjust it, I only noticed the plastic connector to the throttle body.

Answer 1

first locate the detent cable at the engine ( at the throttle body ). there is a clip on the cable that you need to lift up. lift up the clip and unlock the cable. manually open the throttle by hand and let the detent cable pull up. while you hold the throttle open, push the clip back down on the detent cable and lock it back up. now the cable should be adjusted right so that when you step on the gas it will shift the transmission at the right speed. just make sure its not too tight, it needs to have a tiny bit of slack at the cable when the throttle is full open.  you also need to check and make sure that there is vacuum at the vacuum modulator on the back of the transmission. if you pull the hose off the modulator you should feel air sucking into the line. if you pull off the hose and a little fluid comes out, you need a new modulator.