Taters

My kids 98 keeps throwing a check engine light with a generic code (0700). We replaced the neutral safety switch (twice) cause he was having trouble starting in gear (and still does occasionally) and thought it was related to the light. Now in addition to that it goes into a limp mode every once in a while where he can't go over about 40 mph and the rpms are low. Any thoughts?

lawsoncl

P0700 means the trans computer is reporting an issue (solenoids, NSS switch, etc). The trans computer and engine computer are separate units, btw. Usually there is another more specific code with it. Your description of the limp mode sounds more like lack of power, than a shifting issue?

Taters

Yeah it shifts fine, maybe I'll switch out the solenoid and if that doesn't work I may have to have a shop run the code. The parts store only pulls the generic, no additional code.

lawsoncl

The connectors for the transmission are on the passenger side of the engine bay up against the firewall. You can disconnect and clean them, then check the resistance of the three solenoids there (nominally 11-15 ohms). There are three solenoids. One is for the torque converter lockup, the other two control shifting. If one of the shift solenoids goes bad it will shift incorrectly, typically either starting in 4th gear or skipping over 2nd/3rd. If the trans computer is dead (or you pull the fuse) it will try to start in 4th gear in (D), and you can shift manually shift into 1st/3/4th with the shifter. That's actually one method of troubleshooting whether it's a mechanical or electrical problem.

On the neutral safety switch, you may need to adjust it. Easiest way I've found is to put the shifter in reverse, loosen the smaller hold-down bolt, and rotate the whole switch back and forth while watching the reverse lights. Get it adjusted in the center range of where the reverse lights are on, then snug up the bolt.

I'm still confused whether you have a shifting issue, or a loss of power. If he's at 40mph and low rpm, I would expect it to downshift if he's got it floored. Have a look at the throttle position sensor too. If that's bad, it can confuse the trans computer and not downshift.