12V Relay Not Triggering

Hello :-)

I just bought a VIPER 4806 remote starter and keyless entry.
First i want to say thx to the forum, without you i would never have plugged the remote starter !

But now, i have a problem with my doors. I cannot plug it !

My car is an old 2000 audi A3. I've identified the locking and unlocking wire which need ground to activate.
From the Viper, i have 2 negative 500ma output.
I decided to wire relays, in order to have a ground to thoses door lock/unlock.

https://www.the12volt.com/relays/relaydiagram46.html<----- is what i used.



Problem : the relay does not activate.
My grounds are OK.
When i test the wire from Viper, if i activate the remote it shows me a 4-5V then goes down to 0.
When i test beetween 86 and 85 i have 0.5V and when i activate the remote, it goes to 0.4V.

I guess the ground is not strong enough as there is the remaining 0.4V ! and the relay doesn't activate


Can you guys help me ? i've tried like a ton of things, but none work.....

Check from 85 or 86 and the other meter lead on ground of the vehicle. What do you get?

Beetween 86 where the alarm trigger is plugged and ground, i read 12V
Beetween 85 where the +12V is plugged and ground, i read 12.5V

Still this weird 0.5V...

If you connect wires directly from the battery to the relay coil (85 and 86), do you hear it click? Have you tried another relay?

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My ex once told me I have a perfect face for radio.

Yes, if i connect the +12V and ground directly from the battery, the relay click and works.
I've tried 3 differents relays 12V 30A.

Do the same but this time arm and disarm the alarm and let us know what 85 and 86 do. The 12 v terminal should stay at 12. The one from alarm should go to ground. I am betting it is not. If that is the case try this

https://www.the12volt.com/installbay/forum_posts.asp?tid=114792&kw=2n6491#556471

Ok i'll Check that as soon as i come back home.
I ordered the TIP42 but it's a C not a G. I'll have it on monday or tuesday iguess.

If it doesn't go to 0v do you have an idea why ? Known pb with viper ? Bad wiring ?

Either your 12 volt supply is not good, or the output of the alarm is damaged and can not provide the 160 milliamps of current needed to trigger the relay. Using the transistor will work if it is the latter of the problems. But you will need 2, 1 for lock and 1 for unlock. Tip42G is fine. I drew the C in the diagram because when it was drawn Radio Shack retail stores were a thing. That is the one they stocked.

As excepted if i use the remote it only goes from 12V to 11.8. Far from 0V!!
Its weird... i looked everuwhere and it seems that i plugged all the grounds and all the 12V. Is it possible that i missed an important wire ?

Never ever needed relays on one of them.
Extend lock time to close windows and roof if fitted.
Make sure the green lock and blue unlock from the Viper go to ground when you activate lock and unlock on the remote.
And put the meter away, use an incandescent bulb test light to test out puts from Viper, if they are OK use clip on test light to a good ground, probe to each suspect wire, make sure they lock and unlock.
Try making your connections at the factory vacuum control unit, left hand rear just between wheel arch and rear light fitting.

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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.

Windows and roof is not plugged.
I tried to extend lock time on door. It's the same but longer ^^
It's the main problem, when i hit lock or unlock, the wires are not strong enough to go to ground, it goes from 12 to 11.8V only.

They are more than strong enough if 500 milliamp. The older stuff was 120 milliamp and more than adequate, I did loads of them in my time, never needed a relay you've either got the wrong wires or burnt out the lock/unlock circuits on the Viper, the relays needed diodes by the way non or incorrect use would fry those circuits.

-------------
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.

Hello guys,

So i've bought theh TIP42C transistor.
New problem, when i connect the wire from the alarm, it directly triggers the relay without using the remote. :-(

Looking at the transistor so you can see the writing on the face of it, legs facing down, you do have alarm wire connected to the left leg, the middle leg grounded, or the tab of the transistor mounted to the chassis of the vehicle, and the right leg going to the relay?

Do you have an incandescent test light? If so, connect to power and probe the wire that comes from the alarm, does it light up?

yes it's how i wired the transistor. I started with middle leg to ground, then right leg to relay and as soon as i touch the left leg with the wire alarm, it triggers the relay.
I don't have incandescent test light but a multitester, i'll tell you what it says but i'm sure it will be 0 as the relay triggers.

Thx for taking the time to help me :-)

https://www.learningaboutelectronics.com/Articles/Transistor-switch-circuit.php

Mayble i could try this way ? Base would be wire from alarm, emitter would be ground and collector would be door lock. With that i wouldn't even need a relay no ?

Still not working your initial attempt probably fried the lock/unlock circuits, test them first.
Done loads of these neither transistors nor relays are needed.

-------------
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 agree with you Howie its probably fried.
But i still get a little signal so i'm sure there is a workarround

Program aux 1 for timed output, works with arm and connects to vehicle lock wire.
Program aux 2 for pulsed output output works with disarm connects to unlock.
Alternative, factory alarm arm to lock.
Disarm to unlock.
Test any before using, see if 0V, do NOT connect a relay!
Trouble is I think all those outputs are controlled by the same internal
power transistor.

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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.

Well, i've tried everything i could but nothing is working.
I'm giving up, my factory alarm is still working sono guess i'll cary arround my 2 remotes ^^

Thx for the help :-)

I have a similar question.... I'm trying to get either the 820ohm or 330ohm negative signal coming from an 03 Ram to trigger a relay.... the signal isn't strong enough to trigger the relay, how can I amplify the signal?

Measure the voltage on those two wires, DMM to 20VDC, red probe to a 12V+ constant, black to each wire and measure the voltage,
let's say you get 5 volts, then use a relay from Mouser, Farnell etc with a 5 Volt coil.
A regular 12 volt automotive relay won't work below around 7.5 volts.

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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.