Danny D. wrote, on Fri, 19 Dec 2014 23:56:58 +0000:

Debugging suggestions are requested, and very helpful. Thanks!

Here's where the Bryant 373LAV horizontal furnace stands tonight.

Blower starts, inducer motor starts, igniter starts, flame starts,
flame shuts down. Three times the igniter ignites the flame but
three times, the flame shuts down within seconds.

All the while it displays code #34.
At the end of the sequence, it shuts down and displays code #14.

Video:
https://www.flickr.com/photos/98287134@N02/15464227533/

Schematic:
https://www.flickr.com/photos/98287134@N02/15460746143/

Codes:
https://www.flickr.com/photos/98287134@N02/16083106532/

34 IGNITION PROVING FAILURE
- Control will try three more times before a lockout #14 occurs.
If flame signal lost after trial for ignition period, blower will
come on for 90 second recycle delay. Check for:
- Oxide buildup on flame sensor (clean with fine sandpaper).
- Proper flame sense microamps (.5 microamps D.C. minimum).
- Gas valve turned off. - Manual shut-off valve. - Low inlet gas pressure.
- Green wire MUST be connected to furnace sheet metal.
- Inadequate flame carryover or rough ignition.

14 IGNITION LOCKOUT
- Control will auto-reset after three hours.
Refer to #34.