i have a 2003 carvan, how can i test speed control switch. works some times, if i keep push pushing button will start but some times it want.

 

Looking at a wiring diagram they're two ways to check the switch, neither easy. The easiest is to disconnect a connector on the PCM. You'll probably have to remove it to get at the connector. Number two would be to test the switch at the clockspring connector and check it there. You would have to remove the steering wheel.

If you want to check it at the PCM disconnect the battery, remove the PCM. On connector C2 probe pins 41 (dark blue wire) and 43 (violet wire). You should make and lose continuity as you actuate the switch.