B737-800
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Rejected Takeoff; Flight Crew Returned To Gate; General Maintenance Action
Aircraft
We had a normal push; start and taxi out. As we were cleared to position and hold the Captain accomplished the takeoff configuration warning  check. We did not get a takeoff warning horn. The check was completed; we went on to complete the takeoff checklist.  Before we were able to fully line up on the runway the Tower cleared us for takeoff. The Captain (flying pilot) stood up the power levers and I called 'stable.' Captain pressed the TO/GA switch and called 'set takeoff power.' I called 'takeoff power set;' we accelerated normally down the runway; I called '80 KTS.' The Captain responded 'checks;' I looked at the engine instruments one more time they were still all stable as we passed 110 KTS.  The intermittent cabin altitude/configuration warning horn sounded and we aborted the takeoff at 110 KTS at 149.1 LBS. I called 'speedbrake; 100 KTS; 90 KTS.' And at this time the Captain stowed the speedbrake to disarm the autobrake; so we wouldn't come to a screeching halt. We had plenty of runway left and the RTO was violent enough already.  We exited the runway called Dispatch and talked to Maintenance Control to try to understand why the takeoff configuration warning sounded. We brought the jet back to the gate after exiting the runway; stopping the jet; and talking to the flight attendants and then making an announcement to the passengers. The Captain did a great job not only with the aborted takeoff; but also with passengers and crew.
[Narrative 2 had no additional information].
A B737-800 flight crew reported rejecting takeoff at 110 KTS when the configuration horn sounded for unknown reasons.