# Alarm, Interrupt Relay?



## 93ser (Jun 12, 2002)

I'm trying to figure out why my starter interrrupt relay wiring is not properly working on my viper 300esp? The relay is basically triggered from a neg source via the alarm, which occurs only when armed. The relay has pin #85 to (-) output or trigger, #86 to (+) fused constant, #30 and #87a are breaks between the starter wire. Once the alarm is armed the neg output from the alarm activates the relay to open the connection between the starter. I've tested this with a multimeter, but when the relay is connected and the alarm is armed, no neg signal is found. Also I have a diode connected in parallel between #86 and #85, with striped end attached to (+) #86. This diode eliminates the reverse voltage when the relay discharges. I've also discovered a potential of 12 volts across #86 and #85 when disarmed and 5 volts armed. It should be 0 volts and 12 volts respectively.

Anyone have any ideas?

Thanks again,

Travis


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## toolapcfan (Jul 10, 2002)

I'd just replace the relay, sounds like the coil is crapped out, shouldn't be more than $3-$5 for one. However it sounds like you've got bigger problems if the alarm isn't triggering the relay to open the starter citrcuit. If that starter interrupt trigger wire isn't working you could wire a passive starter interrupt. If you have a shock sensor, there should be a power-up wire from the alarm to the sensor, you could use this to positively trigger a relay that will open the starter circuit when the alarm is armed.


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## 93ser (Jun 12, 2002)

*found the problem, but...*

I figured out why my starter kill relay doesn't activate, since the trigger signal and the ignition are both (+). The thing I cannot figure is why the trigger output signal is (+) when is should be (-). If I have to use this trigger wire as a pos signal then where should the grnd be connected so its only activated if the ignition turned.

Travis


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## toolapcfan (Jul 10, 2002)

I'm unsure what you're asking. Don't most starter interrupts keep the starter circuit open the whole time the alarm is armed, not just when it's triggered? Regardless, just ground the one side of the relay coil and let the alarm output positive signal power it. I guess I'm failing to see the problem.  Do you have a wiring diagram for the alarm? Does it say that the starter kill relay is supposed to be triggered with a (-) from the alarm? So when you arm the alarm, you get a constant (+) signal from that wire is that correct? So if that's hooked up to, say 86 and the other half of the relay coil (85) is grounded then when the alarm is armed, the relay should operate.


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## 93ser (Jun 12, 2002)

I originally needed to figure out a switching source that would only trigger the relay when the alarm is activated. Also, if the relay was on the whole time the alarm was armed, then it could drain the battery. 

I managed to get the relay to work off the siren signal, but now i have bigger problems. Now the stereo seems to loose the memory presets when arming, and the digital clock does't work at all. I tried removing this relay and still had no effect. This shit is starting to piss me off now. The funny thing is I've spent so much time trying to figure this stuff out and still this won't prevent a thief from stealing my car. It's so simple to bypass the ignition relay, just cut the power from the alarm. I guess the only real prevention is a kill switch.

Travis


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## toolapcfan (Jul 10, 2002)

You've got something squirrelly going on. If the starter kill relay opens the starter circuit when the alarm is armed, and that's how it's supposed to work, then I doubt the relay is going to drain the battery, a relay coil draws very little current. Now, if the starter kill relay is normally open and only closes the starter circuit when the alarm is disarmed, you'd have the same thing, when the alarm isn't armed that relay coil would be powered up and keeping the starter circuit closed. From what I can tell from your post, the starter kill relay is wired normally closed and when the alarm is triggered, the relay is opened. What a person could do is wire a relay that is always powered as long as the alarm is, and this relay helps to operate the starter kill relay. So if power is cut to the alarm the car won't start, the alarm has to have power and be disarmed for the car to start. It'd be easy to do and only take two relays. But you're right Travis, the best bet is a hidden kill switch. They also have those cards that plug into a harness that completes the circuit and those take a lot of time to disable, since they have like 7 wires all the same color that run deep into the dash where most of the wires loop back to the harness. I've had to undo one of those when someone lost their card for it. It was easy but like I said, took more time than any car theif is going to take, even if they tear into the dash, if it's installed right, they're not going to get anywhere.


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