2008 Dodge Deisel 2500 with a Viper5500. Security module is a iDatalink ADS-TBSL C2.
The vehicle locks work and the lights work. It actually all works fine... except it wont crank... usually.
I have power to the big power wire by the firewall, ignition from the pnk/wh in the ign harness. As the acc and start are all through the multiplex wire, they are not connected to the R/S itself but hooked up through the security module which is supposed to take care of that. There is no listed second ign. Brakes hooked up and work, lights hooked up and work. Module programmed to wait to start about 1 second for testing reasons but once it works i will change to a more suitable value. Currently set to Voltage Test vs. Tach, again for testing reasons.
The security module has the multiple wire wraps in place, power to 12V+, ground to the same ground everything else in the dash is connected too. Status to the R/S status wire. The multiplex control wires are hooked up to the multiplex wire, the +ign wire (from R/S), the +start wire (from R/S). It is also connected to the disarm wire from the R/S to wakeup the truck if its asleep.
Wires checked, all soldered good, tried changing the ground. When i attempt a remote start the ign powers up, the parklight engage but thats it. If I press the brake it shuts off again as it should. Where to key is doesnt affect anything. No crank takes place. However, once in a while the truck will crank and start. It shuts off again after a couple seconds as the module isnt programmed to the key yet but it does start. Unfortunately its so unpredicable, at least for the moment, I havnt had the key in place to test whether that would make it remain running. If I could determine a pattern it would help but it seems completely random to me, except it has only worked with a security module that does not have any software loaded.
The guy is away for a couple days so Im looking into it and have to finish when he gets home. Any brilliant minds out there wanting to flaunt your wisdom?
the security module hooks up to the multiplex
So the "no start" problem is intermitant. Correct?
Have you adjusted the WAIT time ?
brilliant minds.......thats a good one!
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Yeah, I changed wait to start to 10 seconds and tried, same issue. I also set it to look for the wait-to-start wire which I had set up so I controlled it with a gator clip to ground and waited till the light went off on the dash. After the light went out I took the gator clip off ground and then the vehicle made its attampt to start but as usual its attempt to start involved a lot of silence and not very much starting.
LOL Yeah well I figured maybe people could get the chance to show off their prowess and feel good about if I added that. I mean if I cant figured it out you would need to be truly brilliant to be able too 
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i've had a few of the chrysler data bypasses (all been XK532's) that didn't quite mesh with the factory resistance for the multiplexed ign/start/keysense wire. ended up just using it for the locks and sentry key then using a few relays and resistors to go back to the old school chrysler bypass of cutting and measuring. can't recall the values exactly, but i think it was something like the truck was 580ohms and the bypass puts out 610ohms. close enough to work sometimes but not consistent
Yes, the bypass modules I have dealt with, sometimes the resistance is just a little too far off, and depending on the battery level, will sometimes not allow the vehicle to start.
Thanks Another and Mega. That makes sense to me, I will be sure to check that carefully next time he gets in. Currently he is away for 3 weeks on a job. But that makes a lot of sense.
Not sure if the i-datalink bypass requires it but I have to put a 1k ohm resistor in line between the ground and I think the starter wire from the r/s to the bypass. My stuff is at the office so I can't look at it now. I had the same problem on an 07 and putting the resistor in cured the problem.
the xk532's require a 1kohm resistor to ground on the starter input to the bypass on most vehicles (dodge rams for sure).