In a way I started this so I may as well add my tuppence.
The intermittent horn sounds for a ground spoiler fault under the following conditions (ON THE 737NG)
A/C in the air (PSEU function)
Leading edge devices retracted (FSEU function then fed to the PSEU)
Ground spoiler interlock valve open (prox sensor fed to the PSEU - there is also a pressure switch but this is not used for in air intermittent horn)
Landing gear take-off warning cutoff CB closed (on P6)
Regarding the interlock valve - This is a mechanically operated valve, operated by a teleflex cable attached to the lower (sliding portion) of the right main landing gear. So, if for some reason the gear does not extend OR the valve does not close (cable seized, valve seized, etc) then the valve will still be open (note the valve is fail safe and is spring-loaded closed so if the cable breaks it should close)
If the a/c is in the air and the spoiler interlock valve is open the horn will sound as soon as the last LE LED transit light goes out and the LE devices are retracted.
To silence the horn the landing gear take-off warning cutoff CB (on P6) can be pulled. This will cancel the take-off warning horn but will still allow the cabin pressure warning to sound.
OR the landing gear aural warn CB (also on P6) can be pulled. This will silence the horn but will ALSO prevent a cabin pressurisation warning should it occur.
The PSEU has 2 systems 1 and 2, only system 1 is used in the control logic for the horn to sound. The logic within the PSEU seems to be fail safe (as it should be) in design. logic gates requiring voltage (rather than earths) to go true and the final electronic switch is powered (rather than earthed or logic low) to sound the horn. Therefore I doubt a PSEU failure would cause an erronous horn (more likely it wouldn't sound when it should!). BUT - the input to the aural warning unit from the PSEU for the horn to sound is an earth, so a chaff to ground downstream of the PSEU COULD cause a false warning.
Note also that if the gear fails to "unsquat" a secondary effect would be to prevent the normal retraction of the gear. Perhaps the reason for 737 checkers' response.
All gleaned from ASM 31-53-11 'cos the AMM these days is s**te
Hope this helps.
Cheers.