in my 1998 chevy S10, the 4wheel drive doesnt go into 2wheel drive when i push the button.I replaced the main switch at the end of last winter and it was working fine.checked it yesterday and doesnt want to go back into 2wheel. I pulled it out, cleaned all connections, and had it working for a bit. But it went back to only wanting to go into 4high and 4low and not wanting to switch to 2wheel.Any ideas?
I have a few suggestions; first check the vacuum lines at the rear of the engine making sure the two lines connected to a switch at the rear of the engine (firewall) are not disconnected, cracked or missing.
Pull the passenger side kick panel off and look at the module for the transmission. Check for moisture around or in the module causing corrosion at the plug (s). This is a common problem with the 4 wheel drive system of these trucks.
Sometimes the module can electronically lock up. Disconnecting the battery for about ten minutes. Sometimes this resets the module and restores proper operation. Sometimes this works but it is worth a shot.
Is the switch you replaced an after market switch or is it a factory switch (from the dealer). It is a know fact that the after market switches are not made the same as the factory switch and could be causing the problem. If the switch is the problem then try to replace it with the switch from the dealer.
Try these suggestions, if they don't help you then get back to me and we can diagnosis the problem further.