Viper 160xv Remote Start

I just purchased a 2003 Ford Explorer XLT with Viper 160xv installed. At the lot, the remote start and all functions worked fine. After purchase, remote start did not engage starter. Upon activation the instrument panel lights up as if to start, but the starter does not crank. The dealer had no clue how to use the remote so there was a lot of button mashing, but did manage to start remotely if the key is in the ignition and in the "on" position. Then read warning not to do that.

Have install manual:
- Viper does not seem to "learn Tach signal" when that step is performed.
- switched menu to "engine check off" and "voltage engine check" as well as "voltage check high" & "voltage check low" to remove need for tach signal to start, but there was no starter cranking.
- put key in "off" position, but still no remote start cranking.

If you try remote start and it fails (after several automatic attempts), inserting key and trying to start does not engage the starter either. Deactivating the remote start with the remote control has to be performed before the car will start with the key.

I plan to check the AC voltage on the Tach line, but I think that will show a good signal. Any other ideas?

if u put the key in the ignition and it starts by remote, then u have a problem with the security bypass unit that goes with the remote starter,

Putting the key in the ignition only works if the key is in the "on" position, not in the "off" position. From the Manual the security bypass only applies to GM vehicles and this is a Ford.
The car did start on the lot, remotely, with no key near the ignition. I don't know why it is not working now.

you have a transponder chip in the key head, that the computer reads everytime u start the vehicle, u have to duplicate the same thing when you remote start.check fuses on viper module first

The fuses were good. I read all of the other forum inputs on the viper and decided to try putting each key in the ignition, turning each of them on and then off, removing the keys, and immediately attempting a remote start. It fixed the problem.
I don't know why the problem happened in the first place, but I hope it doesn't come back. I guess only one of the keys has the correct chip in it.
Thanks for all of your help.