QX56 cranks but won't start
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From: nova
QX56 cranks but won't start
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I have a 2005 QX56 with a viper remote start/alarm. I purchase the truck with the alarm installed by the previous owner, this was in 2006 the truck had 12,000 miles on it, never had an issue untill today, not even sure if it is the alarm. I believe the alarm is a 479v/p/c (that is what is listed on the back of the key F.O.B, i googled that number and that may just be the model of the remote, so i am unsure the exact model.
Problem:
I remote started the truck, it started ran throught a 10 min cycle and powered off, i then restarted the truck via the remote it gave the signal beep that it turned on and appx 30 sec later it beeped again informing it turned off, ii thought nothing of it cause i have had spoof starts in the past, anyway i got in the truck and attempted to start, the truck started and ran for appx 10 sec then turn off, since that the truck only cranks, i have check the battery, its at 12.8 volts, i talked to one of my buddies and he thinks the kill switch is engaged,
question 1. Does the kill switch controll power or fuel, i thought the kill switch would not even allow the truck to crank,
2. Can someone tell me how to disconnect the alarm or fuse to the alarm if it has one, i don't believe it has a backup battery cause i disconnected the battery in an attempt to reset everyting, while the battery was disconnect i tired using the key fob to see if it would react (thus trying to determine if it had a backup battery)
any suggestion would be appreciated.
I have a 2005 QX56 with a viper remote start/alarm. I purchase the truck with the alarm installed by the previous owner, this was in 2006 the truck had 12,000 miles on it, never had an issue untill today, not even sure if it is the alarm. I believe the alarm is a 479v/p/c (that is what is listed on the back of the key F.O.B, i googled that number and that may just be the model of the remote, so i am unsure the exact model.
Problem:
I remote started the truck, it started ran throught a 10 min cycle and powered off, i then restarted the truck via the remote it gave the signal beep that it turned on and appx 30 sec later it beeped again informing it turned off, ii thought nothing of it cause i have had spoof starts in the past, anyway i got in the truck and attempted to start, the truck started and ran for appx 10 sec then turn off, since that the truck only cranks, i have check the battery, its at 12.8 volts, i talked to one of my buddies and he thinks the kill switch is engaged,
question 1. Does the kill switch controll power or fuel, i thought the kill switch would not even allow the truck to crank,
2. Can someone tell me how to disconnect the alarm or fuse to the alarm if it has one, i don't believe it has a backup battery cause i disconnected the battery in an attempt to reset everyting, while the battery was disconnect i tired using the key fob to see if it would react (thus trying to determine if it had a backup battery)
any suggestion would be appreciated.
Last edited by cutsprings703; Mar 28, 2009 at 06:52 PM.
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From: How long is a piece of string?
Re: QX56 cranks but won't start
The alarm brain may be flaky. The kill switch could be installed on ignition power or fuel, depending on what the installer thought was the best option. It sounds like it's installed on the fuel OR something that would be connected to the ECU power. You can physically unplug the ECU on most cars and the engine will still crank (but obviously not run). Do you hear the fuel pump priming properly before you start the engine?
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From: nova
Re: QX56 cranks but won't start
The alarm brain may be flaky. The kill switch could be installed on ignition power or fuel, depending on what the installer thought was the best option. It sounds like it's installed on the fuel OR something that would be connected to the ECU power. You can physically unplug the ECU on most cars and the engine will still crank (but obviously not run). Do you hear the fuel pump priming properly before you start the engine?
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From: nova
Re: QX56 cranks but won't start
ok update ...
i just went out and checked it and compared it with my sisters truck, my truck in acc mode ( key turned all the way foward without starting) i hear the fuel pump go for appx 2-3 seconds and cut out, my sister's truck keeps running
i just went out and checked it and compared it with my sisters truck, my truck in acc mode ( key turned all the way foward without starting) i hear the fuel pump go for appx 2-3 seconds and cut out, my sister's truck keeps running
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From: How long is a piece of string?
Re: QX56 cranks but won't start
Your truck sounds like the fuel pump relay works correctly; it should prime for a few seconds and shut off until the engine is cranked. I'm not sure why your sister's truck keeps the pump running, that's kinda weird but that probably doesn't mean anything. That could be just a difference in engine management strategy but that's strange nonetheless.
So it sounds like the alarm is probably controlling the ignition system but not the starting system (because the engine is cranking). So I guess the next thing to check is whether you're getting power to the ignition system and ECU. I can't really tell you where to test because I don't know how that alarm was installed and I've never even touched a QX before.
You could still have a kill relay on the fuel pump, and the alarm could be shutting it off early after the engine runs for a while. That's a difficult thing to determine without accessing the alarm and testing its behavior with a multimeter, etc.
My point is that you're probably having an alarm brain problem, or the relay itself is starting to die. Strange things happen when cheap relays start to fail, and they can be related to stuff like mechanical fatigue or thermal effects like heating up when current runs through them. If you can find where that kill relay is, you can remove and bypass the relay, or temporarily jumper the relay coil so that it is active all the time when the ignition power is on. That will obviously only work if the relay is good.
So it sounds like the alarm is probably controlling the ignition system but not the starting system (because the engine is cranking). So I guess the next thing to check is whether you're getting power to the ignition system and ECU. I can't really tell you where to test because I don't know how that alarm was installed and I've never even touched a QX before.
You could still have a kill relay on the fuel pump, and the alarm could be shutting it off early after the engine runs for a while. That's a difficult thing to determine without accessing the alarm and testing its behavior with a multimeter, etc.
My point is that you're probably having an alarm brain problem, or the relay itself is starting to die. Strange things happen when cheap relays start to fail, and they can be related to stuff like mechanical fatigue or thermal effects like heating up when current runs through them. If you can find where that kill relay is, you can remove and bypass the relay, or temporarily jumper the relay coil so that it is active all the time when the ignition power is on. That will obviously only work if the relay is good.
Last edited by Fabrik8; Mar 28, 2009 at 07:24 PM.
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From: nova
Re: QX56 cranks but won't start
ok thanks a mil,
i will follow up with all you have suggested at day light tomorrow, please check back with this tread sometime tomorrow if u can, and i should have an update, once again thanks.
i will follow up with all you have suggested at day light tomorrow, please check back with this tread sometime tomorrow if u can, and i should have an update, once again thanks.
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