Electrical Viper 3400v alarm blows fuse with 5-wire door lock relays

Oct 30, 2018
18
1
3
California, United States
#1
Trying to install a Viper 3400 alarm on my 1990 LX hatchback. Having issues with the door lock actuators. I've got everything that I'm going to hook up working (siren & marker lights - I'll throw in the hatch release and starter interrupt once I get these door locks figured out). The door locks work fine when not using the alarm (meaning, when I throw the switch on the door panel the doors will lock and unlock properly).
I'm using two SPDT relays to operate the door lock actuators, but I keep blowing fuses as soon as I try to lock or unlock the car with the fob.
The first time I wired up the alarm, I took my constant hot for the brain from the cigarette lighter circuit (lighter is not used and the only other thing on that circuit should be the horn). I took my constant power for my door lock actuators from the same location. Figuring that might be the problem, I then took my hot for the actuators from the headlight/marker switch. But I then started blowing THAT fuse while the cigarette lighter fuse was fine.
Checking the leads on my Bosch style relays with a test light, I had hot on 86 and 87 and nothing on 85, 87a or 30 (Type B relay with no diode). When I would click the lock button on my fob, I would then get a second or so of hot to pin 30 (verifying, I think, that the relay is functioning properly). Did the same thing with the other relay with the unlock button and it worked as well. As soon as I connect pin 30 to the pink/yellow or pink/green wire (which is where I get a pulse when the door lock switch is thrown) and click either lock or unlock on the fob, I blow the fuse on the circuit the relays are on.
I've tried reversing the hots between 85 and 86 and still blew the fuse. I also tried reversing the hot between 87 and 30 and still blew the fuse (I've gone to every site that I could find mentioned on this forum in regards to wiring these relays and find that they're just not consistent with regards to which terminals should be hot...so I've tried them all).
What am I missing? I know this topic has been pretty well beaten to death, but any help would be greatly appreciated!

I should add...I haven't tapped into the ignition wire yet. Not sure if that's important for this or not. My concern with the ignition wire is, why does the brain have 18 gauge wires tapping in to 12 gauge wires??? Is that something that should concern me, or should I just hook it up and not worry about it?

On a side note...when I blow the fuse on the headlight/side marker switch circuit, why do the headlights and side markers continue to work properly??? I purchased the car a couple yeas ago as a project car, but just now getting around to it. Was just curious if this headlight switch is working properly or if the previous owner changed the wiring to the lights or something.

tl;dr
seems the relays are wired and working as expected but as soon as I connect the relays to the door lock wires, I blow the fuse that the relay's are on. Door locks still work normally without using the fob.
 
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Oct 30, 2018
18
1
3
California, United States
#2
I just found some information from a car stereo web site that says, when installing 5-wire relay's to an alarms door lock actuator,

"you have to cut the factory relays and hook up the aftermarket relays as shown".

That's the first mention I've seen (I may have overlooked that in other threads, but I never noticed that before) in any thread or link that pertains to car wiring and door lock actuators. Do I, in fact, need to remove factory relays to get these door locks to work? If so, then they'll only lock/unlock via the fob, right?
If that's the case, couldn't I wire the 12v supply to the factory relay to post 87a of the alarms relay so the door would still lock/unlock with the factory switch in the door panel whenever the fob isn't activated???
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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#3
I would think twice about cutting factory wires, I'm kinda funny about that, I've dealt with cut wires from stereos, ignition and speaker wiring.
i would look for a way to build a harness or unpin stuff to make it work. But it's your car.
 
Oct 30, 2018
18
1
3
California, United States
#4
I would think twice about cutting factory wires, I'm kinda funny about that, I've dealt with cut wires from stereos, ignition and speaker wiring.
i would look for a way to build a harness or unpin stuff to make it work. But it's your car.
Thanks!

Still need to know what would cause the fuse to blow when adding 12v to the actuator wires. Anybody???
 

90sickfox

I didn't really have an issue with the stink...
SN Certified Technician
Mar 2, 2015
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#5
The factory ford wires reverse polarity ti lock and unlock. That would reverse polarity at the alarm relays input/ output blowing the fuse. When I installed my Autopage alarms they had very good instructions and worked flawlessly. Aftermarket alarms all wire basically the same.

I can't remember exactly what I did but I don't remember completely cutting the door lock wires. I do remember tapping into them at the driver's kick panel.

The Autopage had remote start, keyless entry, opened and shut windows, LED fob...etc. The instructions are available pdf files. Might be something in there to help you out.

The center pins reverse polarity when the relay is switched. Wish I could remember exactly what I did.
 
Oct 30, 2018
18
1
3
California, United States
#6
As I understand it, the fox body door lock switch sends a positive pulse to the door lock actuator. So, the actuators need a pulse of current to operate them. This is apparent when I check the wires with a test light and the light illuminates when I hit the switch.
The alarm sends a ground (negative) pulse through the door lock wires. Therefore, 5-wire relays are necessary to convert the ground pulse from the alarm to a positive pulse to operate the door lock actuators (else a negative pulse would hit the already negative leads to the actuators and do nothing).
Since I tested both relays with the test light and they appear to be working correctly, sending a positive pulse when I hit the button on the fob and illuminating my test light, I don't suspect the problem being between the alarm and the relays. I can click the fob buttons all day long without blowing a fuse so long as the relays are connected to the test light. Once I connect the relay to the door lock wires, then the fuse gets blown when clicking the lock/unlock buttons on my fob.
So, what would be between the relay and the door lock actuators that would be causing a blown fuse??? It may very well be that only one circuit (either the lock or unlock side) blows the fuse. I'm not sure if they both blow the fuse, but it seems only the lock side may have been blowing the fuses - I ran out of fuses testing stuff and couldn't verify this. I would guess there's a short between the relay and the door lock actuator, but wouldn't that keep the factory door lock switch in the door from working the actuators as well? If so, what else could be causing the blown fuses???

I should add, although I don't thing the unlock side ever blew the fuse, it never worked the actuator either.

After reading about 20 different pages on installing alarms in fox body's that was the first I had heard of removing a factory relay. So, I was skeptical when I read that and just wanted to check here.
Thanks for your input!
 
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Oct 30, 2018
18
1
3
California, United States
#8
O.K. Lets try this a different way. I've blown the 20 amp fuse from the cigarette lighter circuit. I've blown the 15 amp fuse from the headlight switch circuit. I'm using 30/40 amp SPDT relays. Do I need a circuit with more headroom for amperage? Do I need different relays? Does anyone suspect a short somewhere (I haven't been able to locate any)?
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
9,771
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polk county florida
#10
From the lack of responses I would say nobody here can help, have you contacted the manufacturer tech line?
 
Oct 30, 2018
18
1
3
California, United States
#11
So...I took power for the door locks from the black/white behind the left hand dash speaker. This wire is where the drivers door lock switch gets power and is behind a 30 amp fuse. I also tapped into the pink/yellow and pink/green wires which connect to the driver side door lock switch at the same location. My constant power for the "brain" of the alarm still comes from the cigarette lighter/horn circuit.
When arming and disarming the alarm, I DIDN'T blow any fuses! But, I could hear what sounded like the door lock actuators, but the locks didn't lock/unlock. The driver side switch in the door still operates the door lock properly. The sound I heard was similar to that of when you try to unlock already unlocked doors. I switched the green and blue door lock wires from the alarm (from one relay to the other) thinking I just had them reversed, but I get the same results...the muted sound of the door locks working, but they don't.
It seems I'm getting close
tango_face_smile_big.png


Anyone experience this sound when installing their alarm?
 

wiseguyk

Active Member
Sep 23, 2016
299
75
48
Florida
#12
So I was just reading through your thread and while I'm not 100% following what you've tried so far, your experience is very familiar to what I went through when installing the keyless in my 91. I was blowing fuses too, and my dumb-ass decided to put a bigger fuse in and ended up burning up one of the internal relays in the keyless module :mad:

I couldn't really tell from your posts, but if so far you have just been "tapping" into existing lock wires, that will not work for the fox locking system. I believe it's what's called a 5-wire alternating 12v system like this diagram shows https://www.the12volt.com/relays/relaydiagram3.html

This means that to get the alarm/keyless to work, you'll actually have to cut the two factory lock/unlock wires and wire in the alarm lock/unlock relay wires to them. Once I figured that out and wired it up it worked like a charm. All Viper systems I've seen have a built in 5-wire or external 5-wire relay box so you should be able to find the instructions for that type in the Viper manual.

I could only find one pic from when I did it, but you're already on the right track going through the dash speaker hole. I banged my head for a while trying to get at those wires from under the dash and once I went in through the top it was much easier. Good luck!

1542747532149.png
 
Oct 30, 2018
18
1
3
California, United States
#13
I am using two 5-wire relays from the green and blue wires from the Viper brain. If I cut the door lock wire, then I would be relegated to always using the key fob to lock/unlock the door, right??? Meaning, the switch on the doors armrest will no longer work???
 

wiseguyk

Active Member
Sep 23, 2016
299
75
48
Florida
#14
I am using two 5-wire relays from the green and blue wires from the Viper brain. If I cut the door lock wire, then I would be relegated to always using the key fob to lock/unlock the door, right??? Meaning, the switch on the doors armrest will no longer work???
No sir, when you have the Viper 5-wire relays configured correctly the physical lock/unlock buttons will work even when there is no power to the alarm/keyless module itself.

My Viper keyless manual had a section with details on which wires to use for the 5-wire style system so I just followed those and everything worked as it should.

Once you cut each factory lock/unlock wire, you will have to test each end to see which side is the actuator side and which is the switch side because that is crucial when wiring up to the 5-wire relay.
 
Oct 30, 2018
18
1
3
California, United States
#15
I'm not following how you can cut the wire and connect the 5-wire relay and still have the switch in the door work. Aren't we cutting the wire from the switch in the door to connect the 5-wire relay??? What do we do with the end of the cut wire that doesn't get connected to the 5-wire relay???
 
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Oct 30, 2018
18
1
3
California, United States
#16
To clarify...I'm "tapping" into the door lock wires with t-taps. Once I establish things are wired correctly I plan on pulling the t-taps and soldering the connections. I'm NOT simply attaching the green and blue wires from the alarm directly to the t-taps in the door lock wires. I'm attaching the green and blue wires to 5-wire relays and connecting the relays to the door lock wires.
The relays take the ground pulse from the alarm and "convert" it to a 12v positive pulse. This is needed because the fox body's use a positive pulse to operate the door locks.

@wiseguyk...how did you connect the relays to the door lock circuit? Did you solder the wires or use some sort of connectors? Did you connect the relays to the pink/green and pink/yellow wires?
 

wiseguyk

Active Member
Sep 23, 2016
299
75
48
Florida
#17
I'm not following how you can cut the wire and connect the 5-wire relay and still have the switch in the door work. Aren't we cutting the wire from the switch in the door to connect the 5-wire relay??? What do we do with the end of the cut wire that doesn't get connected to the 5-wire relay???
I didn't wire up 2 relays myself because my Viper keyless unit had a built in relay module which does the same thing but a bit easier to wire up.

Since you'll be cutting the factory lock and factory unlock wire, you'll have 4 ends to connect to the relays. Both ends of the two factory wires will be wired up to the relays such that when in the default state the door lock switches will work as usual.

Here is the snippet from a Viper manual showing how the wiring is done with two relays so hopefully it helps clarify:

1542750107538.png
 

wiseguyk

Active Member
Sep 23, 2016
299
75
48
Florida
#18
To clarify...I'm "tapping" into the door lock wires with t-taps. Once I establish things are wired correctly I plan on pulling the t-taps and soldering the connections. I'm NOT simply attaching the green and blue wires from the alarm directly to the t-taps in the door lock wires. I'm attaching the green and blue wires to 5-wire relays and connecting the relays to the door lock wires.
The relays take the ground pulse from the alarm and "convert" it to a 12v positive pulse. This is needed because the fox body's use a positive pulse to operate the door locks.

@wiseguyk...how did you connect the relays to the door lock circuit? Did you solder the wires or use some sort of connectors? Did you connect the relays to the pink/green and pink/yellow wires?
You updated before I posted my last reply :p The issue is that you cannot simply tap into the fox lock/unlock wires and pulse them to make it work. This is due to the reverse polarity nature of the lock system. That is why you'll have to physically cut the lock and unlock wires and wire the alarm lock relays to them.

Edit: A lot of other auto lock systems use a simple +/- pulse to trigger locking, but the fox system is not one of those which is the reason the 5-wire relay configuration is needed.
 
Oct 30, 2018
18
1
3
California, United States
#19
You are the MAN! That makes perfect sense!
The way to keep the door switch working is to wire it to pin 87a, instead of not using it at all. I guess most of the diagrams I've seen for this are for people adding after-market door lock actuators where they don't need to keep the door switch operational.
 

wiseguyk

Active Member
Sep 23, 2016
299
75
48
Florida
#20
Haha awesome, glad I could help! It had me confused at first too so I completely understand the frustration :)

Let us know how it goes
 

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