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Alright I have done my homework and think I figured this out but need some advice just to make sure. I don't have access to post a picture so I am going to post a link to my wiring diagram for my car

https://manualspace.com/acura-integra-1990-1993-wiring-diagram.htm (Pages 12,23,24)

I am trying to wire in the rear defrost to a remote start without bypassing the timer circuit.

This is what I have figured out:

when the rear defrost switch is pushed it sends a ground signal through the rear window defogger timer which sends a negative pulse to the rear window defogger relay which activates the relay and allows 12v to flow to the rear defogger. Does this sound accurate?

If I am correct on this all I should need to do is connect the remote start defogger output (-200 mA) to the Yel/Grn wire on the timer side of the switch. I shouldn't need a relay for this since the remote start activates the ignition 2 (12V switched for the relay) correct?

If I want to wire this to activate the rear defogger by button even if the car is not started I could wire it into one of the aux channels on the alarm and use a relay on the Blk/Yel wire to send 12V through when the aux channel is activated correct?

A couple of points:

1. The timer most likely sends a latched negative to the relay, not a pulse.
2. I doubt the signal (negative) from the switch to the timer is only 200mA. If you wire the 200mA to the switch side of the timer you risk burning out the rs unit and 200mA may not be sufficient to activate the timer. (Depending on the amp output of the switch [which I assume is probably 7.5A], you could diode isolate the rs 200mA wire, but I'm no expert with using large amperage diodes and there's still no guarantee that 200mA will activate the timer).
3. I'd wire the 200mA rs defog wire to the negative side of the defog relay coil.

If I use the 200mA rs to the negative side of the defog relay won't that bypass the timer? I am trying to avoid doing this so it would be best to wire in a relay to boost the ground in my original plan and diode isolate the relay from the normal circuit correct?

Yes, but the rs (which one are you using?) should have a built in timer for the 200mA negative latched output. The DEI responder models use 10 minutes, at least the viper and clifford matrix do. Unfortunately, that time is not programmable, even with a bitwriter.

You run very minimal risk of "burning the output of the defroster from the remote start output" as mentioned by Mr. Joebubba, if you connect it to the negative trigger from the switch, there are two possibilities, it works or it doesn't!

Is the susupect wire thin or thick gauge?

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COMMIT YOUR WAY TO JEHOVAH AND HE WILL ACT IN YOUR BEHALF. PSALMS 37:5

I don't have access to the car right now i'm deployed and am trying to plan my install for when I get back. I believe it's 7.5 Amp circuit. Sorry forgot the alarm model number it's a 5901

^^^No, I said it the other way around. The defrost switch output could burn out the rs circuit that supplies the 200mA if not diode isolated.

Yeah, that's the Viper (DEI. Same as Clifford matrix 50.7x and the python 7??). You can hook the blue wire (#5) of the remote start aux output harness to the neg side of the relay coil.

The output from that wire can be set to supply a latched output 10 seconds after the car is started when the temp is 55 or below....( a note, the temp sensor is notoriously inaccurate on the DEI models)

Or it can be programmed to a 10-minute latched output which is activated by the remote (push f 4 times, then remote start button. this can be activated independently of the rs. This is how I have mine set up on my acura.

So the remote start has a built in timer in itself is what your saying. So if I programmed it to be a 10 min latched output which is activated by the remote this means I can turn the defrost on without activating the remote start? Can I program it to do both? Turn on when the remote start is activated or independently of the rs.

Thank you for all the advice I am trying to get into the world of remote starts,alarms, car stereo's and am trying to learn as much as I can.

^^^^to clarify, I ran a separate fused (40A)power wire from the battery and used a separate relay for my set up. I tapped the power output of the relay to the defog power cord. (The rear defog relay in the acura tl is in the under hood fuse/relay box. The neg input to the relay coil comes direct from the control block underneath the relay and I couldn't figure out how to access the negative side of the coil. In addition, it runs off a 30A circuit, so I was tentative about hooking up a 200mA wire from the rs to this circuit.) Either way, I had to transit the firewall.

No, you can't set it to do both. The install manual can be found here:
Viper 5901 install manual

The info you need is on pg 26 and pg 51 (option 3-11).

Ok so simply connect this to the negative side of the rear defrost relay and it should work. Do I need a relay to boost the ground signal and/or do I need to diode isolate this wire from the rest of the circuit? I don't think I need a diode but i'm still learning.

On a side note what did you guys/gals use to learn how to do all this and what to use where?

tegguy wrote:

On a side note what did you guys/gals use to learn how to do all this and what to use where?

Some of us used meters and test lights. Some of us use the internet. When some of us began doing this, Al Gore had not even thought about the internet. We had no choice but to use a voltmeter to determine which wire did what function.

i am an idiot wrote:

tegguy wrote:

On a side note what did you guys/gals use to learn how to do all this and what to use where?

Some of us used meters and test lights. Some of us use the internet. When some of us began doing this, Al Gore had not even thought about the internet. We had no choice but to use a voltmeter to determine which wire did what function.

Good Ol Al Gore...... I have been researching but there is just so much information out there it gets confusing and then trying to figure out what rating of a diode to use and type just seems like I will never get a grasp on it.

I'd use a relay to isolate it. You could diode isolate it I guess, but I've never used the large amperage diodes before (I assume the amperage on the diode will depend on the amperage of the circuit driving the neg side of the coil). They may cost more that a standard $10 relay and they are subject to failure.

joebubba wrote:

I'd use a relay to isolate it. You could diode isolate it I guess, but I've never used the large amperage diodes before (I assume the amperage on the diode will depend on the amperage of the circuit driving the neg side of the coil). They may cost more that a standard $10 relay and they are subject to failure.

Ok so just use a relay to boost the ground and also will work to isolate the circuit and would look something like

85 R/S rear defog wire

86 12 v const

87 to r/s ground

30 ground

I read earlier that you may want to be able to turn the defrost on without the vehicle being remote started. The only way that this would be possible is if you caught the defrost wire between the relay and the defrost element on the rear window. Grounding the defrost relay's trigger wire will not work if the vehicle is not turned on.

For what we use diodes for, the only rating that matters is the current capacity of the diode. If using it on the coil wire of a relay, a 1 amp diode 1N4001, or any thing between there and a 1N4007 will work fine. If using it to isolate or power left and right parking lamps, a 3 amp or a 6 amp is more of what you would need. Radio Shack sells 1 amp and 3 amp diodes. You can parallel 2 of the 3 amp devices to achieve a 6 amp capacity.

No, I think it would be this:
85 12v+
86 r/s 200mA output
30 ground
87 to neg side of defog relay coil

i am an idiot wrote:

I read earlier that you may want to be able to turn the defrost on without the vehicle being remote started. The only way that this would be possible is if you caught the defrost wire between the relay and the defrost element on the rear window. Grounding the defrost relay's trigger wire will not work if the vehicle is not turned on.

I was thinking about doing this but it isn't that big of an issue and you are correct becuase the relay for the rear defog runs off 12v switched.

I put the wrong wire I meant to say 87 to rear defog relay

does 85 and 86 matter which is positive and which is negative?

i am an idiot wrote:

I read earlier that you may want to be able to turn the defrost on without the vehicle being remote started. The only way that this would be possible is if you caught the defrost wire between the relay and the defrost element on the rear window. Grounding the defrost relay's trigger wire will not work if the vehicle is not turned on.

Yes, I believe that's correct, because the + circuit in the factory defog circuit is controlled by the ignition.

And I can't imagine why anyone would want to risk running the battery down by running the defog on battery power only. That circuit sucks a lot of power! (40A in the Acura)

tegguy wrote:

does 85 and 86 matter which is positive and which is negative?

Nope, as long as the relay doesn't have a diode across the coil.

There is a European standard that states 85 is ground. I have never seen one, but some relays do have an internal diode. As stated earlier, if there is a diode across the coil, it does matter which leg of the diode gets the positive voltage. If the relay has an internal diode, it will be installed where 85 is ground. I always use 85 as ground, just incase the relay has an internal diode.

Ok thanks for the advice I am just now learning how to use relays

i am an idiot wrote:

I read earlier that you may want to be able to turn the defrost on without the vehicle being remote started.

This is what I have been trying to understand.... WHY?

If you are defrosting the rear glass... arent you going somewhere? If you are just wanting to warm your hands on the rear window, you can buy hand warmers at Cabelas.

Well the reason why I was thinking this is my car likes to fog up even if it isn't that cold out so I figured why waste gas if I don't need to warm or cool the car?

It is always good to have your rear glass fog free. It makes it easier for everyone to see what you have in the car. Oh wait, that might not be a good idea.

Well the most times I would use it would be leaving work on a military base so it really isn't an issue with theft there.

You know, since the start of this thread i've wondered the exact same thing kartune did! Why? LOL!

You'll lose gas yes, but an active relay with the car switched off drawing at 7.5 amps constant, could take a toll on the battery!

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COMMIT YOUR WAY TO JEHOVAH AND HE WILL ACT IN YOUR BEHALF. PSALMS 37:5

t&t tech wrote:

You know, since the start of this thread i've wondered the exact same thing kartune did! Why? LOL!

And if you would have read all the post you would have seen I provided a reason as to why I was looking for this.

Point taken! Cheers! i do apologize for my idiotic thoughts!

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COMMIT YOUR WAY TO JEHOVAH AND HE WILL ACT IN YOUR BEHALF. PSALMS 37:5

Well, I can't believe I missed this:

Why not just wire the blue wire programmed for a pulsed output to a relay that connects the black wire on the ground side of the defog switch ( or any ground for that matter) to the GREEN/ YELLOW wire on the other side of the switch? (pg 24). This would simulate pushing the switch. Of course, I'm assuming the switch is a momentary switch, not a on/off switch.

85 -200mA pulsed from viper (wire #5 of the remote start aux output)
86 +12V
30 tapped to black wire on defog switch (or any ground)
87 tapped to yel/grn wire on defog switch

The rear defog should behave just as if you manually pushed the switch. This should work since the switch is not a data signal but a simple ground signal.

t&t tech wrote:

You run very minimal risk of "burning the output of the defroster from the remote start output" as mentioned by Mr. Joebubba, if you connect it to the negative trigger from the switch, there are two possibilities, it works or it doesn't!
Is the susupect wire thin or thick gauge?

Now how is it possible that the post to the top of this page was now thought of?

Had he answered my original question, this thread would have ended a long time ago! The answer lies right in the original poster's first post!

There is also a possibility you may not need the relay, just conect the defrost output directly to the trigger wire at the switch, again it either works or it doesn't, if it doesn't you insert the relay!

Geez!

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COMMIT YOUR WAY TO JEHOVAH AND HE WILL ACT IN YOUR BEHALF. PSALMS 37:5

Well, believe it or not, it was original and didn't come from your post...but thanks for playing and being such a stand up guy!!!

Take it eays bro! I never said it came from my post! Read again!

I never intended to argue here, it's just that, as sherlock would say it, the answer is elementary my dear watson! Cheers! lol posted_image

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COMMIT YOUR WAY TO JEHOVAH AND HE WILL ACT IN YOUR BEHALF. PSALMS 37:5