Printer Friendly Forum Posts - viper 5902 defroster connection

I have a '99 Tahoe with a Viper 5902 installed w/ SmartStart. I have (2) problems. The first, I don't know where to hook up the Blue/White Defroster wire from the Viper to the defroster circuit, behind the heater/AC assembly the defroster has a plug with 2 constant hots, a ground and the 4th wire is hot when the button is depressed and stays hot until it shuts off after a few minutes, Do I need a relay to connect my Viper to the defroster. Second, I installed the SmartStart and activated it myself through the website, via a user and password I found online, not being an installer, everything went fine except I didn't activate my aux channels, after I rec'd' my activation email, I completed and paid for the year, now when I try to use my Aux channel to operate my windows from my phone, it says "Aux wasn't activated at the time of install (36)" when I went back to the site and entered my airId, it says its not associated with the user anymore, I think because I never put in an installer e-mail when I activated the SmartStart. Can anyone help or direct me to what I need to do to get these (2) issues resolved. I would really appreciate any help.

You can use this diagram for your particular application. Ensure that you program the blue/white wire for latched output. The diode is optional but it is recommended.

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This information is provided only as a reference.
All circuits should be verified with a digital multi-meter prior to making any connections.

You can also test to see if jumping (touch & release) one of the +12v wires to the +12v when button pressed, turns on the defrost (lights up the switch). If it does you don't need to cut the factory defrost wire just tap the relay into the +12v to 87,86 and the +12v when pressed to 30, 85 to trigger (set to pulse) This way the switch will time out just like normal, as if you pressed the button. This method is the preferred way so if the defrost mode is turned on in the summer the factory switch will shut it off by resistence instead of being latched until the remote start shuts off.

Sounds like a trip to an authorized dealer is in order to get the activation properly registered.

Thank you for the diagram. I'll try this weekend.

lurch228 wrote:

You can also test to see if jumping (touch & release) one of the +12v wires to the +12v when button pressed, turns on the defrost (lights up the switch). If it does you don't need to cut the factory defrost wire just tap the relay into the +12v to 87,86 and the +12v when pressed to 30, 85 to trigger (set to pulse) This way the switch will time out just like normal, as if you pressed the button. This method is the preferred way so if the defrost mode is turned on in the summer the factory switch will shut it off by resistence instead of being latched until the remote start shuts off.

Sounds like a trip to an authorized dealer is in order to get the activation properly registered.

its not a very smart thing to just jump the 12v wires together, what if the switched wire rests at ground? you will blow a fuse or fry the control. if you want to jump the wires then you need to test it first to make sure the wire doesnt rest at ground. at the very least you need a 1A fuse inline when you go jumping wires to see if they work.

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91stt's diagram is 100% correct, also X 2 with soundnsecurity, sorry Lurch you are quite WRONG in what you suggest, but then we had this out last week didn't we.
What part of motor wire/hot window feed is GROUNDED at rest don't you realise.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

I can't wait till the weekend to hook this up. Is there anyway to correct the aux channels on the smartstart activation site. They are active on the Viper through my bit writer and active on my smartstart app on my phone, just not active through smartstart. Again, I appreciate all of your input.

howie ll wrote:

91stt's diagram is 100% correct, also X 2 with soundnsecurity, sorry Lurch you are quite WRONG in what you suggest, but then we had this out last week didn't we.
What part of motor wire/hot window feed is GROUNDED at rest don't you realise.

I've been doing the older chevrolet cavaliers and the like from the late 80's early to mid 90's that way for years, and it works flawlessly. I have a 1989 Chevy Cavalier that is hooked up this way and has been since 1994 and is still working to this day.
Common sense to test the wires first, if the wire goes direct to the rear element it can be hooked up that way. If not on the GM's it will be a feed to a relay, and will need to be latched. I wouldn't tell him to try this if it would damage the vehicle and as far as I know it only applies to GM's and that is what he is working on.

But that's why we need to know how to test first don't we. If he doesn't know how to test then he shouldn't be attempting this install!

Your 1999 Tahoe has an integrated solid state timer delay relay in the HVAC control switch assembly that operates the defogger for 10 minutes. The recommendation is to make your connections as indicated in the diagram provided. This is the safest method to activate the defogger. Tapping the violet wire with 12 volts will backfeed the control switch and may damage it since it is not known what is in that little black box. This method will work regardless of whether the wire normally rest at ground or not and will isolate the upstream components. The time and cost to cut and make the extra connection is insignificant compared to the cost to replace the control unit if it is damaged from the 12V backfeed.
Although not shown in the diagram, the 12 volt supply must be fused. Use a 30A fuse to match the factory fuse size.

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This information is provided only as a reference.
All circuits should be verified with a digital multi-meter prior to making any connections.

On the older swtches it is a latched relay circuit with a resistance based shut off as the element heats up the resistance changes when it hits the set resistance it shuts off. The new ones may be solid state but if it direct feeds to the element, then it's using a latched based allbeit solid state relay to engage the output. The only change is the circuit is timer based instead of resistance. And the timer gets it voltage from the output side of the unit. So it is basicly backfeeding the timer by design, so triggering the relay and timer with a pulse would be no different than pushing the button.

This is only tested to work on GM direct feed to defogger element type systems.

howie ll wrote:

91stt's diagram is 100% correct, also X 2 with soundnsecurity, sorry Lurch you are quite WRONG in what you suggest, but then we had this out last week didn't we.
What part of motor wire/hot window feed is GROUNDED at rest don't you realise.

We are all here to help as well as learn and anyone who thinks they are only here to help are on a never ending fools errand. I might not be up to speed with all the newest and greatest units and vehicles. But how many people nowadays can even operate a computer without a mouse or GUI to interface for them. The accepted way to use a computer is with a mouse, does that mean it's the only way it can be done. No it's not, so don't be so quick to dismiss what you either don't know or have never tried.

You're missing the point. 99% of output wires be the lock actuators, window motors or rear defogger hot wires are ground at rest; thus applying a feed will blow your fuse. That's the point I was making + the safety factor of a changeover relay.
I know certain Mercedes, Euro VW etc. were 12v+ (+) at rest and some door locks, inc. London taxis were open circuit but that's why we test as you said.
By definition a permanent magnet motor will have both wires either 12v+ or ground (-) at rest.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

a computer is not a car, cars need to be interfaced in certain ways to prevent damage. some cars are more forgiving than others but just because something works on one car doesnt mean it translates to another car as you should know well. yes we are all here to teach and learn but if you are going to teach then you need to teach the best way not the good enough way.

sure, you know that you should test the wires but the people who ask questions probably wont, so based on your advise, someone might just start jumping wires together. is that your fault? not really, but can it be avoided by giving better explanations? yup

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Quite right.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

That may be true in a generic application but we are talking about a Specific vehicle (99 Tahoe), for a specific type of defroster using a single pulse to activate the defrost. Not door locks, window motors or any other low resistance circuit. As a defroster element is high resistance (High Resistance = Heat) so it's not a direct ground per se. That by design is likely to get to hot if latched to a remote start that can run for 24 minutes with a defrost that is timed to only run for 10. And you are bypassing the control switch negating the 10 minute limit all together. Will it take this sure, but for how long? You're also not erroring on the side of caution that some one will unknowingly turn the winter mode on and remote start a car on a very hot day and overheat the window element causing it to fail. Being politicly correct or following popular opinion AKA the accepted way which means in most cases not all. So that's the other side of the coin on that matter.

This round to Lurch on points.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

I can't tell you how appreciative I am for everyone taking the time to explain and attach diagrams to help me out. I have the tools, common sense and am mechanically inclined, just didn't understand or have ever used a relay, but have sure learned a lot the last few days. Does anyone have any input on how to fix the smartstart aux channels via the activation website. I live chatted with Viper Customer Service, but they were unable to help. Basically, she said I had to go back to my installer to have this corrected, I didn't dare say I did it myself with an online user/password. I guess the airId gets associated to the installer that logs in or enters his info during the activation process, I just left that blank as I went through the process, trying to go back into it with the same online info now says my airId isn't associated with that user, is it in limbo somewhere.

i used to have a DEI account but im not with that shop anymore or i would help you. you will need to find an installer with an account. best buy would probably be the most common place that sells viper so maybe try there or a local shop if you have one near by that sells viper. im pretty sure anyone with an account can change your settings because that wouldnt make any sense to only be able to modify your account through the same installer.

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lurch228 wrote:

. That by design is likely to get to hot if latched to a remote start that can run for 24 minutes with a defrost that is timed to only run for 10.

well, with that knowledge i would still keep my wiring the same, but i wouldnt latch the output. most remote starters will let you use a timer mode on the defroster channel and even if it doesnt you can still use a timer like the PAC TR-7 to work within the limits of the vehicle's design.

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The timer leechs it power from the output when latched so sending a pulse to the 12v output engages the latch. So it runs off the factory control as normal. It's a matter of preference really as to how you want to hook it up. For this type of defrost either way will work.