check engine light 99 durango

I installed a Skytek G40 remote start w/keyless unit in a 99 Doge Durango. When I remote start it I get a check engine light.  This vehical has a factory security system that need a negative pulse to disarm. The Durango does not have a transponder key.  The Skytek unit does not have a disarm wire present.The instructions say to use the unlock wire and dioed isolate and conect to the unlock and disarm wire. Then program the unit to unlock before start than relock after start. I figured this shoul work.

Here is the problem. When I remote start with the lock/unlock harnes disconected The truck starts and runs fine with no check engine light. When I plug un the lock/unlock (also dissarm) harnes in. Then arm the factory security and then remote start it. The doors unlock,the security diss arms and the the truck starts. Then I get the check engine light. The check engine light comes on every time the car is remote started with the lock/unlock harnes pugged in.  When I clear the codes with the scanner the truck runs fine with the key. The customer had no check engine light before the install.

The only thin I can think of is that the timing of the diss arm + unlock and start are too close together.

Yes I did diode isolate each wire correctly. I also checked the diodes and my connections with my DVOM. I also soldered all my connections too.

On this vehical the diss arm requires a negatie pulse and the door unlock wire requires a positive pulse. I used a polarity inverter for the door locks to change the polarity to positive output. I dioed isolated the unlock wire befor the connection to the polarity inverter.