Manual override switch for EWP question
Manual override switch for EWP question Hey, im wondering what kind of switch i would need to get. Im a noob with electronics so i have no clue. From what i have seen at an auto store, ive seen switches with 2 prongs on the end of them and with 3 prongs. Im guessing i would need a 2 prong one? One to go to the wire between the trigger wire from the relay to the power source and the other wire to go to a 12 volt power source for the switch? Some help would be appreciated, thanks.
Joined: Nov 2003
Posts: 11,331
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
There are two types of switches that have three terminals. One type is actually a three position switch (On/Off/On) used to control two devices but these aren't commonly found in stock at auto parts stores. The other type is actually a two terminal switch with an extra terminal for lighting - there will be a light in the switch that goes on when the switch is on.
So your choice of two or three terminal switch depends on whether you want a light in the switch or not.
So your choice of two or three terminal switch depends on whether you want a light in the switch or not.
Joined: Nov 2003
Posts: 11,331
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Think of a switch as an adjustable break in a wire - it can connect or disconnect the wire. So you can use it in any wire that controls your accessory. You can put it in the power lead to the relay (one end to 12V+ and the other to the relay) or you can put it in the ground wire for the relay (one end to ground and the other to the relay). Either way the relay will shut off when the switch is off because it needs both power and ground to complete the circuit.
Ohhh ok, i see what ur saying. Well ls1howto suggests that it gets wired into the trigger wire running from the fusebox to the relay, and putting diodes on the trigger wire before the wire from the switch and on the wire from the switch to the trigger line. I guess what i dont know is if i need to have a power source for the switch or not.
Joined: Nov 2003
Posts: 11,331
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
No, you don't need a separate power source for the switch. It's not a powered device, it's merely a control for the circuit it's installed in. Also, you don't need diodes in the circuit - in fact, you probably don't need a switch. If the author at ls1howto had given it some more thought he would have realized that there are simpler ways to accomplish what he's doing.
I assume you want to set up your EWP so that it is running whenever the car is on and also have the ability to run the pump for a while with the car off. This is easy to do without a switch. Connect the pump using an ordinary 30-amp automotive relay so that it runs off of constant (battery) power but have the relay triggered by an ignition controlled accessory circuit. To do this, connect terminal 30 to battery power (get it at the junction box on the left fenderwell), terminal 87 to the power lead of the pump, terminal 85 to ground, and terminal 86 to an accessory power source. The accessory power source will probably have to come from inside the car because I don't know of any accessory power source under the hood. You can tap in at the BCM, the radio, or the fuse panel to get accessory power. Make sure everything is fused!
This arrangement has the pump running whenever the ignition is on regardless of whether the engine is running. So if you want to continue running the pump after shutting off the engine, just turn the ignition switch to the ACCY position. It also eliminates the possibility that you might inadvertently leave a separate switch on and drain your battery.
I assume you want to set up your EWP so that it is running whenever the car is on and also have the ability to run the pump for a while with the car off. This is easy to do without a switch. Connect the pump using an ordinary 30-amp automotive relay so that it runs off of constant (battery) power but have the relay triggered by an ignition controlled accessory circuit. To do this, connect terminal 30 to battery power (get it at the junction box on the left fenderwell), terminal 87 to the power lead of the pump, terminal 85 to ground, and terminal 86 to an accessory power source. The accessory power source will probably have to come from inside the car because I don't know of any accessory power source under the hood. You can tap in at the BCM, the radio, or the fuse panel to get accessory power. Make sure everything is fused!
This arrangement has the pump running whenever the ignition is on regardless of whether the engine is running. So if you want to continue running the pump after shutting off the engine, just turn the ignition switch to the ACCY position. It also eliminates the possibility that you might inadvertently leave a separate switch on and drain your battery.
The author did mention connecting it to a pink wire in the IGN box, which would have the pump running when the car is on the ACC position. Problem with this is, when u are trying to do tuning, often times u need the key in the ACC and that will have the pump on and drain the battery ALOT quicker. Thats why he suggests hooking up the trigger line to the fuel pump (Which turns on for 3 sec then shuts off while the key is in the ACC position.)
I thought the exact same thing u just said (why do u need a switch if u wire it up to an IGN source.) I would rather just install the switch cause i do plan to learn how to tune my car in the future. But you have helped with alot of info. I think im ready to install the switch. Thanks alot for ur help.
-Ryan
I thought the exact same thing u just said (why do u need a switch if u wire it up to an IGN source.) I would rather just install the switch cause i do plan to learn how to tune my car in the future. But you have helped with alot of info. I think im ready to install the switch. Thanks alot for ur help.
-Ryan
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Joined: Nov 2003
Posts: 11,331
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Actually, there are ignition controlled circuits under the hood that are powered with the ignition in the ON position but not in the ACCY position. If you aren't interested in running the pump without the car running then you could use one of those (e.g. the pink with black wire at junction box #2 on the left fenderwell) to control the relay.
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