Bad siren output

A friend of mine got a problem with his alarm, the siren output is fried. The alarm is a Viper 550esp. The output for the alarm reads 3-4 volts continuously  regardless if the alarm is going of or not. The voltage doesn't even change when you arm/disarm the system or  when you set off the alarm or use the panic function.

He doesn't have the cash to get a new one and he asked me to try to fix it. At first I thought about using the parking lights output to to power the siren and at least chirp with the lights, but then if he turns on the lights on the car the siren would go off. But that has an easy fix. If I put a relay on the lights output wire after the wire for the siren the lights would flash off this relay and be isolated.

The problem is with the RS part of the system. As you all know this system turns on or flashes the PL when the car is running with the remote starter. And that would mean that the siren will either chirp or stay on for as long as the RS is on.

Does anyone have an idea as of how I can get around this? Like I said getting a new system is not an option at least not in the near future. And no he can't  just take it back to the dealer who installed the alarm as this car has been trough two owners before him and the original owner was the one to put in the alarm and he got it from a reseller with no warranty. By the way I checked the installation and fix the problems it had( t-taps everywhere) but the siren is still on the air.Please don't suggest that he changes the alarm. I have a few alarms here but he wants the alarm/starter combo he's got( very stubborn m***** f*****).

Any and all ideas are welcome!

I redid all the connections because the guy who did the original install used t-taps on all of the connections. Now they're all solder. And sending the unit in for repair would probably cost more than buying a new Audiovox APS-786t ($95 shipped) which has more features and cost less than the Viper.

But right now he doesn't have the money to do either, so  I have to somehow make this thing work. The alarm part I have figured out but the remote starter part is the one that I can't get around. 

So I need a way to bypass the siren while the remote starter is on without loosing the parking lights(the siren would be connected to the parking lights circuit to at least get the siren chirping).