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I've been looking at relay diagrams to try to understand them better, but I'm still confused. Do these two relays serve the same purpose (of cutting fuel when the alarm is armed)? I want to have the option to key start my car/remote start my car.

Relay 1
Pin 85- orange wire from dei alarm (ground while armed)
Pin 86- BLACK/ red ignition at key switch
Pins 87 and 87a- either side of the BLACK / YELLOW fuel pump, cut and tie to the relay

Relay 2
pin 86- 12v
pin 85- ground while armed.
87a gets the key side of this fuel pump wire
pin 30 gets the other side of this cut wire.

Does one have an advantage over the other or are they completely different all together?

Thank you

Hmmm I've been searching and I read that, "87 and 87a are never connected to each other". So to create a fuel cut relay, I would just use a Normally Closed Starter Kill Relay for the fuel pump wire?

Diag 1
https://www.the12volt.com/relays/page2.asp

30 and 87a are connected when 86 and 85 are not energized. when 86 and 85 are energized then 30 connects to 87. Relay 1 is wrong . When I mean energized it would mean that either 86 has positive and 85 has negative or 86 has negative and 85 has positive. Thats they only way they energize

Thank you for clearing that up and making it very easy to understand haha.

Yes ...relay 1 will only 'trigger" when the key is on. You need constant 12 volts to the relay to work when you arm.

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I would recomend against method 2, as the relay will be energized whenever the car is off and the alarm is armed. This will put a ~200mA load on you battery at all time, roughly 4x the 'normal' acceptable load on a cars electrical system when not running.

The 'relay 1' method won't work either how you have it, as you can't use pins 87 and 87A like that. You need to use 87A and 30.

The first method doesn't actually cut fuel until the ignition is turned on (the first thing you do when hotwiring a car. At that point, the fuel pump will be disabled, making it 'impossible' to steal the car. The downside to this is that IF they try to hotwire the car they will most likely be able to hear the relay clicking on and off with the ignition, which makes it very easy to bypass it.

You could always go with solid state relays - no clicks and VERY low load.

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Kevin Pierson

I would assume using it is ok because its the same as using a starter kill.....wouldnt see any difference other then using the fuel pump and not the starter..

KPierson wrote:

I would recomend against method 2, as the relay will be energized whenever the car is off and the alarm is armed. This will put a ~200mA load on you battery at all time, roughly 4x the 'normal' acceptable load on a cars electrical system when not running.

So a standard "starter kill" is not ideal for a cars electrical system as well? Is it not the same theory? You "open" the starter wire when you arm the car, you open the fuel pump control when you arm the alarm.... it's the same thing.... isn't it?

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KPierson,

Thanks for pointing that out. I will go ahead and wire the relay to the ignition for now and replace it with a solid state during my next order.

Wondering what your answer to KarTuneMan's question is as well

KarTuneMan,

I've never seen a 'standard' starter kill that uses 12vdc on one side of the relay.

How much current does a standard Bosch relay pull? I've seen them routinely read >225mA.

How long will the reserve capacity of an OEM battery support a 225mA load? Lets say there is a 120min reserve at 25A (Optima specs). Also, remember this load is in addition of anything else that the car is already drawing at rest. I have fixed cars that would have the battery die if left sit for 4-5 days. I personally would rather have someone steal the car then worry about jumping it every time I leave it sit!

Most of my alarm installs have been DEI. The starter kill relay has an orange wire and a yellow wire. The orange wire is (-) when armed and the yellow wire is ignition (This is what I consider 'normal' for a starter kill application). I did some Audiovox alarms and I always hooked the starter kill relay up the same way. If you know a way to prevent the battery from dying if left sit for a few days please share.

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Kevin Pierson

KarTuneMan wrote:

KPierson wrote:

I would recomend against method 2, as the relay will be energized whenever the car is off and the alarm is armed. This will put a ~200mA load on you battery at all time, roughly 4x the 'normal' acceptable load on a cars electrical system when not running.

You "open" the starter wire when you arm the car, you open the fuel pump control when you arm the alarm.... it's the same thing.... isn't it?

Every starter kill application I've installed the starter kill relay is NOT energized when you arm the car, but when you turn the ignition on while the alarm is armed. I think that that is important to point out here.

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Kevin Pierson

KPierson wrote:

Every starter kill application I've installed the starter kill relay is NOT energized when you arm the car, but when you turn the ignition on while the alarm is armed. I think that that is important to point out here.

Agreed. Never connect a starter kill relay to constant 12 volts if the alarm is supplying a ground when armed.

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the12volt • Support the12volt.com

OK, I did some research to illustrate my point:

On my car, a 2004 Infiniti G35 coupe (twin turbo'd :) ) my stock battery is rated at 65a/h.

Say you add a relay that pulls 225mA and your car pulls 25mA in standby (reasonable values). With a brand new, fully charged battery, it will be dead in less then 11 days. Without the relay in the mix your brand new battery will hold a charge (theoretically) for 108 days.

As batteries age the a/h rating will drop, so these numbers will get smaller and smaller.

It's all a numbers game that can be calculated out with decent accuracy as long as you know the values of the given components (load and reserve capacity of battery).

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Kevin Pierson

So if the relay is energized, that small/slow steady draw will significantly reduce battery life...

Is there an alternative way to wire this relay without running it directly to 12v? I found this relay diagram to arm the alarm while a stand alone turbo timer counts down.

https://www.lagvoid.atotchat.org/240sx/tt.pdf

**I know the Viper 5900 comes with a built in turbo timer, but I already have a TT installed and I don't have to press anything to activate it.**

Eager for your replies! thanks

Yes, wire it up like 'relay 2' in the first post. You can't hotwire a car if the ignition isn't on, so use your igniton and (-) when armed output to control the relay. As soon as the ignition is turned on the fuel pump will be disabled, assuming the alarm is still armed.

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Kevin Pierson

Ok, things are starting to make sense now. Thank you all for the relays 101 lesson!

The problem is not the tach learn or crank time, but the relay itself. The relay is being triggered (cutting fuel) during the remote start process. It runs perfectly fine when started with the key.

Fuel Cut Relay:

85 > orange from primary harness (ground when armed)
86 > BLACK/ red ignition
30 and 87a > fuel pump wire

Does the fuel pump wires being (-) change the way the relay works? Pin 85 is taking the ground from the fuel pump wires and kills the car. I'm really confused right now because it runs normal using the key. When I bypass the relay, the remote start works fine as well!

what you can do is bypass the relay with the (ground when running wire)....cut the orange wire and connect it to 30 and 87a. connect the blue wire from where the tach wire is to 85 and use 12v ign for 86

Does it remote start when the alarm is disarmed?

I almost seems like the relay is being energized during cranking because 1. your ignition is on AND 2. your alarm is armed. Try disarming the alarm and see if that helps.

If it does, you can use a 2nd relay to prevent this from happening by using the 2nd relay to make sure your first relay is killed whenever the car is remote started (using the (-) status out or a couple of other ways).

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Kevin Pierson

enice] wrote:

what you can do is bypass the relay with the (ground when running wire)....cut the orange wire and connect it to 30 and 87a. connect the blue wire from where the tach wire is to 85 and use 12v ign for 86

I'm sorry I don't get how this would work.
The manual shows the blue wire as, "supplies 200mA output as soon as the module begins the remote start process". Am I supposed to leave the fuel wires connected to 87a and 30?

I tried remote starting while the alarm was armed and disarmed. I believe the problem is that the ignition wire I'm using shows constant ground. Even when the alarm is disarmed, the orange (ground when armed) wire also shows ground! I didn't think the ground would travel through the relay like that but my knowledge is extremely limited (as you can see). Should I look for an alternate fuel wire? I would be interested in how to use a 2nd relay to kill the first when remote starting. So many relays this is crazy!

KPierson wrote:

Does it remote start when the alarm is disarmed?

I almost seems like the relay is being energized during cranking because 1. your ignition is on AND 2. your alarm is armed. Try disarming the alarm and see if that helps.

If it does, you can use a 2nd relay to prevent this from happening by using the 2nd relay to make sure your first relay is killed whenever the car is remote started (using the (-) status out or a couple of other ways).

Where did you tap the ignition wire?

A relay is simply a resistive coil. If you put either 12vdc or ground on one side of the coil (pin 85 or 86) and leave the other side of the coil floating (not connected) you will read the exact same signal on both coil wires (the signal will bleed through the coil as long as the circuit isn't completed). So, to test your (-) when armed wire you would need to pull the relay out of the socket to remove the coil.

I can't see why the car would start fine with the key but not with the remote start. Unless you tapped the ignition out of the remote start system. Even then, it should still work unless your ground when out has been damaged (output a - at all times).

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Kevin Pierson

Hmmm the ignition wire looks like this:

key---X thick pink from satt x---x #86 relay x---engine

I checked #86 and it sees 12v only during key on. I removed the relay and the small orange (-) when armed does not show ground. I'm about to try moving #86 to connect in between the keyside and alarm main ign wire. Please point out my stupidity if you see what I'm doing wrong!

I don't think moving the wire will help.

When you try remote staring the car see if you have 12vdc from pin 85 to pin 86 of the fuel bypass. If you do, then you will need to cut one side of the relay (say the orange side) whenever you remote start. You can do this by connecting the ignition wire to the relay and the (-) status out (should be small blue) to the other side of the second coil. Then, wire the orange wire going to the coil of the first relay to pin 30 and install a jumper wire from pin 87A to the coil of the first relay where the orange wire used to go.

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Kevin Pierson

I moved the #86 relay and the same thing happens. Remote start dies, key start works.

Tach signal has power when the engine is running. Tach has been learned. I also tried changing to voltage, but the same thing happens.

Does it sound like the car is starving for fuel? Try bypassing this cutoff and see if that allows you to start the car remotely. It doesn't sound like you are confident that the fuel cut relay is what is causing your problems. The first thing you need to do is identify the problem, then you can work on fixing it.

So, to identify the problem, eliminate the relay (wire pin 30 and 87A together to bypass it).

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Kevin Pierson

Sorry I wasn't clear earlier. I bypassed the relay and the remote start worked. The car is starving for fuel. It does the exact same thing when I leave the fuel wire cut.

I just checked pins 85 and 86 while remote starting and you were right. It's showing 12v only during remote starting.

WOW it took me a few reads to picture the 2nd relay you described but I think I get it! I know this is redundant but just in case I got something mixed up.

Relay 1 #85 Orange ground is cut
Relay 1 side of orange ground connects to Relay 2 #87a
Relay 2 #30 connects to alarm side of orange wire just cut
Relay 2 #85 connects to small blue (-) status output
Relay 2 #86 connects to ign

That is brilliant! Gonna go try it out now. This is pretty fun aside from the bumps I'm running into. Thanks for all your support.

KPierson wrote:

I don't think moving the wire will help.

When you try remote staring the car see if you have 12vdc from pin 85 to pin 86 of the fuel bypass. If you do, then you will need to cut one side of the relay (say the orange side) whenever you remote start. You can do this by connecting the ignition wire to the relay and the (-) status out (should be small blue) to the other side of the second coil. Then, wire the orange wire going to the coil of the first relay to pin 30 and install a jumper wire from pin 87A to the coil of the first relay where the orange wire used to go.

SUCCESS

Thank you so much for helping me out/walking me through all my simple questions! I really appreciate it.

I really wish I could edit my post, but I'm still in noob status.

you can't edit your posts after someone else posts after you, or after like 5 mins or something like that.

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Kevin Pierson

I'm with KPierson all the way on this, ONLY EVER use armed output and ignition(live on cranking) to the relay coil, otherwise watch your battery even a type 68 run flat OVER NIGHT! Unfortunately one major alarm manufacturer doesn't use a dedicated ign. standard wire but one side of the onboard (internal) immobiliser is used instead, thus hard to use impossible to use fuel cut in for instance BMW (light green purple) European GM (Vauxhall, Opel, RED / blue) as they are primer cables and shut down on engine run. The advantage is that once car has started any other problems wont be related to alarm(subject to testing ign and starter sides of alarm immobiliser outputs. Regards