Do not Flash, pilot light stays on
My 430 EII does not flash & the pilot light stays on
Repair guides and support for the Canon Speedlite 430EX II external flash assembly.
Does the flash fire when off the camera? Are the batteries fresh?
I have found that most not firing problems are due to dirty contacts on either the flash or the camera, however be careful when using electrical contact cleaners as it can melt plastic. Spray on a cotton bud and carefully wipe the contacts. I hope this helps.