ca 670 remote start stopped working

I have a CA 670 that I installed in my 03 F150 2 years ago, and it has been working fine until recently.  A month or so ago, when the weather turned very cold, I noticed that the remote start would not work if the temperature was below 20 degrees F.  If I tried to start it with the remote, the engine would turn over, and then the alarm would activate.  If the vehicle was warm, the remote start would work fine.  While waiting for the weather to warm up so that I could troubleshoot the problem, the remote start stopped working all together.  When I press the remote, an icon right below the car on the LCD screen comes on, the parking lights flash 4 times very quickly,  the remote plays the sound that you normally hear when you turn the remote start off from the remote, but the starter never engages.  I've tried resetting the tach speed, but the system will not even go into the program mode for the tach.  I have checked the manual, and there is nothing regarding the icon on the remote that appears when trying to start the vehicle.  I've checked the tach wire and made sure that it is still hooked up correctly.

Does anyone have any idea what the problem is before I go tearing in to the wiring?

Thanks.

Bryan

The parking lights flashing 4 times indicates the red handled safety switch is either in the off position, is unplugged from the brain, or is damaged (i.e.,  bad/open switch, or cut wire between the switch and the brain.  I would start by ensuring the switch is in the on position (I'm assuming, of course, that you know where the switch is mounted--under the dash, kick panel, etc.).  If it is on, look under the dash to locate the Brain and ensure the 2 pin switch connector is plugged in. If so, just trace the wiring back to the switch & ensure the wiring is OK.  If all else appears fine, I would replace the switch.

Thanks for the help.  I went out to my truck at lunch and sure enough, one of the wires going to the safety switch had broken off of the back.  I'll get that fixed tonight and then proceed with troubleshooting the cold weather issue with the remote start.  I believe that I am using the universal type of bypass, so I'll start with that first.

Thanks again to both of you for your help!

Bryan