2006 frontier rs cranking kills battery

Hey there techs.....Im having an issue with a 2006 nissan frontier.  I installed an APS-686t from audiovox originally with an expresskits ptbkVI (universal key in the box) bypass.  The customer had no complaints for the first couple of weeks....but the truck soon developed a problem.....Customer states that it starts up fine first thing in the morning but at night it would just crank and crank and not start the truck....It in turn drains the battery down, so low he has to jump it to start it.....obviously his dissatisfaction becomes my number one priority and id wanted to get this squared away for him....he brought the truck in and it seemed it was not seeing the key wrap.....(key light on in dash during rs crank).....i rewrapped the ignition and it still wasnt seeing the key....after a twenty minutes of checking connections and searching for a replacement for the outdated immobilizer bypass i decided to toss in  an xk07.....boom key light is off and the truck started and ran fine.....neways....afater about an hour of sitting i tried it again and it cranked but no start and a dead battery....have already been through all my connections  they all are fine....nothing out of the ordinary with this truck you know...i did pulse the door trigger after start to shut off the autolights in case he decided to shut the truck down without going anywhere..... and all standard functions (lock/ unlock) are good....this battery draw is really killing me and it sure as hell is making the shop look bad.  Does anybody have any thoughts on this topic.  I hope i included enough info to get this topic started

thanx

thanx for super quick replies guys....about load testing the battery......the customer "had it done"  and it tested fine before and after removal of the rs.  no i have not measured the current draw but it seems as if the excess draw is only during crank....the truck holds a charge fine if sitting and untouched but if you try and remote start it it dies during the crank process.   I did tag the second start wire at the key cylinder i used a relay activated by the pulse during crank off of the avox starter.....I did not know that the second accesory wire is only required for rear defrost.....perhaps it did not need to be hooked up.....I did program the starter to off during crank for the second ignition wire as this is how it tested with my meter when starting with the key......

im sorry im not looking at the tach connection right now but if memory serves me correct i did get it at a coil pack not sure right now....i realiize that directed says it can be tagged at an injector.....but my boss is a real stickler when it comes to getting tach at an injector and if i can measure tach at a coil pack to get it there  "because it is safer"......

If it is the case that i got it at a  coil pack do you guys see any possible problems posed by this?

thanx again...sorry i couldn't give you a definite answer