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OEM and Viper immobilizers


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Hoping someone may be able to help. We have a 2002 Nissan Maxima that we bought and it came with a Viper aftermarket alarm/immobilizer/remote start. 

The car car was running well, but now after a bunch of work and now the gas tank reinstalled and battery moved to trunk it is no longer running. We were dealing with the Ecu no longer having power, but found a loose Viper wire that seems to have solved that. Now, the car will crank, fire up strongly and then promptly die. We know the fuel rail has fuel and can't cant say about spark yet with out a bit more diagnosis time (we ran out of daylight and gave up for the day). All grounds seem to be in place and fuel system was put back to normal as opposed to the surge tank we were installing. Only a couple of error codes but all related to evap leaks, etc. Though, Our local

mechanic says we typically wouldn't see immobilizer codes with our generic eBay OBD reader. Security light seems to be gone with the dash (we have the light panel still but can't find its plug, but we haven't cut anything additional out since it was running well previously).


Lots of trouble shooting left to do, but we are pretty bad at electronics and how new ECUs are so dependent on multiple systems. Before we spend too much time looking at some of the typical trouble shooting (TPS, crank sensor, etc) I have a few questions:


 - would this be a symptom of either the oem immobilizer (NATS/NVIS for nissans) or the Viper system. Does either of them let the car fire but then shut it off right away? Or do they typically not even let the car fire up in the first place?


 - does the Viper system override the NATS/NVIS oem system that recognizes the key?  I would prefer to remove the Viper alltogether. But if I don't actually have a proper key with correct chip/code, I'm a bit nervous the thing still won't start up. 


Any thoughts or help would be much appreciated!!

Edited by thewheelerZ
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16 hours ago, thewheelerZ said:

does the Viper system override the NATS/NVIS oem system that recognizes the key?  I would prefer to remove the Viper alltogether. But if I don't actually have a proper key with correct chip/code, I'm a bit nervous the thing still won't start up. 

The override typically involves hiding a chip key near the lock within the steering column plastic clam shell, you NEED to get rid of the viper to have a reliable racer... Look for that hidden key and make sure to plug everything back in or you risk chasing your tail in this diagnostic.

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  • 2 weeks later...

typically the Viper system will either use a hidden key or a module programmed to the key.  if it uses a key, it will have a ring wrapped around the ignition switch.  if it has the module it will be spliced into the wiring on the ignition switch. either way, your symptoms are of the OEM security kicking in.  if anything the Viper system would bypass that and help it start normally, if its working right.  are you using the original key to start it?  it sounds like you aren't using the original key, and the Viper system isn't working right. 

i would remove the viper system and reconnect any wires that were cut.  i'd solder them back to make sure you aren't introducing any extra resistance. if the car still doesn't start, i'd see about getting a new key from the dealer that is programmed using your vin so it should be good.  after that, you may just have a bad ECU. 

is there any company that can delete the factory security out of the ECU?

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FWIW to close this off, I did find the answer to these questions.   Dealer said that not correct key wont even let you start the engine at all, if even let it turn over.  We had a local Viper installer come over (who drove a brand new C43 Merc by the way... maybe im in the wrong business...!) and he helped us out with which wires are for what purpose.  Basically said that a Viper system also wouldn't let you even start the engine (typically cut fuel or spark/crank position as those are the easiest to access).  Also said just go ahead and remove it as there wouldn't be anything that would change otherwise.


So we have confirmed that we are using the original key.  From research, it looks as if there is no way to override the Nissan system.  Removed all of the Viper components and soldered them in as you mention.


Traced the no start to a bad MAF.  Before the winter it ran, we removed the maf and intake to do some work, replaced it with no changes and then it didnt work.  Go figure I guess.  Maybe sitting out in the air expedited corrosion? Maybe it was dropped or something? Car breaths fire again, race day in just over a week!

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