.... I have a timer in the same data module that is being fired properly each second.
It's not clear from your post if the timer of which you speak is a TTimer component, nor is it clear if the timer is just for "quick and dirty" testing. However, it should be noted that if you intend to use a TTimer component in a service application, it must be created at run time. You cannot just drop one on a data module and expect it to work correctly.
More details:
http://www.aldyn.ru/demos/0001/4.html--
Kevin Powick