Posted by on February 15, 2012 at 12:00 AM UTC
Any time a siren or lightbar is 'intermittent' it usually means there is a power issue. Check connections at all terminals, splices, plugs, fuses, etc for positive and ground. To be 100% sure of good grounds connect straight to the negative terminal of the battery.
Also disable all interlocks such as Siren Lock, Park Kill, etc. because these settings could also cause the siren and lights to be inactive. The majority of failure modes cause the fuse to blow or the device will not work at all.