Where to tap ignition on/acc wire?

Szalkerous · #1 10-13-2007, 01:30 PM

Hi all,

I need to tap the ignition for an A/V system I'm installing. Given the amount of components, I am going to mount an additional fuse array in the glovebox. The question is, where can I tap the power source to get power in On/Acc ?

The Chiltons diagrams stink. Anyone pleeeease?

-Sz

Trevor · #2 10-13-2007, 03:26 PM

In order to minimise voltage drop, you should run a substantial wire from your sub fuse board, to fuse board terminal No. FB - 17. This Terminal is not in use and is supplied from 20 Amp fuse No. 3, which in turn is supplied via the accessory circuit. Alternative terminals but which already have connections, are numbered 12 & 13.

Alternatively, you could tap into the cigarette lighter circuit, as close to the fuse board as possible. This circuit is also supplied from fuse No. 3. This wire is coded blue/grey.

kwren · #3 10-13-2007, 04:03 PM

Quote:

Originally Posted by Szalkerous

Hi all,

I need to tap the ignition for an A/V system I'm installing. Given the amount of components, I am going to mount an additional fuse array in the glovebox. The question is, where can I tap the power source to get power in On/Acc ?

The Chiltons diagrams stink. Anyone pleeeease?

-Sz

the one that comes directly from the 4 wire cable from the ignition sw. You should test it for voltage with the sw off and the ignition sw on accessory. this connector plugs into a connector right beside the steering column, and naturally the wires change colors at the connector. that would be the best place to pick up a 12 v connector. This cirket is on a slow blow 45 amp fuse so you should protect your A/V with appropriate protection
If you don't work it out tomorrow I will have a little more time and can check it out for you.

Trevor · #4 10-13-2007, 05:07 PM

Quote:

Originally Posted by kwren

the one that comes directly from the 4 wire cable from the ignition sw. You should test it for voltage with the sw off and the ignition sw on accessory. this connector plugs into a connector right beside the steering column, and naturally the wires change colors at the connector. that would be the best place to pick up a 12 v connector. This cirket is on a slow blow 45 amp fuse so you should protect your A/V with appropriate protection
If you don't work it out tomorrow I will have a little more time and can check it out for you.

The circuit suggested above is that which supplies fuse No. 3.
N.B. For very good reason I have suggested that you should pick up your supply subsequent to fuse No. 3.

A wire to your sub board added as suggested above, would provide a short circuit opportunity in respect of 45 amp main fuse No. 4. The OEM set up wisely separately protects each circuit subsequent to this fuse for safety reasons. In the event that fuse No. 5 blows, the main ignition circuit is interrupted, and motive power is lost, together with headlights. Not good in many circumstances.

If necessary Fuse No. 3, can be upgraded to say 20 amps, in order to cope with an added load, and adequate protection would remain in place.

Szalkerous · #5 10-13-2007, 09:22 PM

So as I understand it, if I want to draw an infinite load, but base it off the ignition toggle, I should use one of the fused ignition lines as a relay trigger for a hardwired line?

I do not want to sit behind any fuses if possible, and at most be the "main" fuse only. I am adding in another fuse block for the a/v equipment, if which those individual fuses would blow first in the event of a bad circuit, etc. I despise the thought of having to wire this in with a toggle switch. I don't want to use the factory wiring because the total load would probably exceed the safe load rating of the 22/20 gauge factory wiring.

Therefore, I'd like to get as close as possible to the ignition switch. Based on my analysis of the horrible Chiltons diagram, the black/white wire off the ignition switch is for the "start" position, and is unacceptable. There is a red wire leading off that I'm not sure where that heads?

-Sz

Trevor · #6 10-13-2007, 11:53 PM

The terminology used is rather confusing.

However I assume that you require to draw the maximum load possible, while ensuring that any connected load will be disconnected when the ignition switch is turned off.

Your best and easiest approach will be to establish a completely new circuit directly from the battery by means of a heavy wire, importantly with an in line fuse fitted as close as possible to the battery terminal. Do not leave out this protection.

Incorporate a heavy duty 12 volt relay with a normally open contact, within your new distribution fuse board, to switch the new separate supply. Then control this relay via a feed from fuse No. 3. The cigarette lighter circuit is usually used because of easy access.

An existing circuit used for audio is another alternative. Any under dash stuff will be fused and can be used. Simply test for voltage with the ignition switch in the accessory position, as kwren has suggested.

The above arrangement will be electrically perfect and will involve the minimum of damage to existing loom wiring. There will be the very minimum of voltage drop, which appears to be a major concern due to an expected a high current. Furthermore, it will prevent an extra heavy load being applied to the ignition switch and circuit.

Szalkerous · #7 10-14-2007, 09:46 AM

Thanks Trevor! That's what I was thinking as well, it's just good to hear someone else agree. (Sanity Check).

-Sz

subarufamily · #8 10-14-2007, 12:31 PM

i used the hot switched wire for the radio it is a pain to get at though

crazyhorse · #9 10-14-2007, 03:53 PM

In my Leggy wagon, I installed a 500watt power inverter. I did almost word for word what Trevor said. I ran 12ga wire (actually an amplifier install kit) with a 40a fuse. My inverter has a 30a onboard, so I depend on it to blow first, it's easier to access than the monster fuse under the hood. It's on a low power interrupt relay. If the battery falls below 11vdc the relay "drops out"