monkeyposeur Posted December 26, 2012 Share Posted December 26, 2012 I am going to do the Power Mode mod to my '93 SS w/4EAT. This involves grounding pin 4 of the TCU. I want to install a switch so I can turn power mode on an off. A simple toggle (two prongs) switch on the ground wire would work, but it would be cool to have one with an led. I bought a three pin rocker switch with a red LED. It has three prongs, (power, accessory, and ground). However, I am not sure if it would work since it is normally used to power an accessory. Can I use this rocker switch as a simple ground switch or will it send a current to the TCU? I don't want to do that. TIA Link to comment Share on other sites More sharing options...
I Donated bucko3the7man Posted December 26, 2012 I Donated Share Posted December 26, 2012 I don't know about your car specifically, but a lighted switch has one wire for the thing it's switching, one wire for the light, and one for ground. Shouldn't affect operation. Link to comment Share on other sites More sharing options...
monkeyposeur Posted December 27, 2012 Author Share Posted December 27, 2012 Right, that's how my rear defroster switch is for example. But in this case I am not wanting to power something, just switching/connecting a ground. I found this image of an led rocker switch. In the diagram the acc wire is powering an led light source. I don't want to get a voltage through the acc wire in my case. I am thinking this setup won't work for what I want and I might just have to use a two prong toggle switch instead. I guess I better get out the multimeter and play around with the switch. Link to comment Share on other sites More sharing options...
monkeyposeur Posted December 27, 2012 Author Share Posted December 27, 2012 I really want this light to go on when I engage the switch, lol. Now I am thinking that I can wire the switch to a relay that will connect the ground from the TCU pin to the chassis when I hit the switch. I've never messed around with this kind of stuff so if anyone has any ideas let me know. Would a 4-pin relay work for this application? Link to comment Share on other sites More sharing options...
subikid90 Posted December 27, 2012 Share Posted December 27, 2012 I am almost positive this is not possible using ground. I am sure you could use some crazy electrical circuit to make it work lol -Subikid90 1997 Legacy GT 5spd & EJ251 w/EJ25D heads ~10.5CR 1998 Legacy GT Limited waiting for EJ22T hybrid swap Link to comment Share on other sites More sharing options...
monkeyposeur Posted December 27, 2012 Author Share Posted December 27, 2012 Dang it! Well, at least the 'Power' indicator on the dash will come on using the simple toggle switch. Link to comment Share on other sites More sharing options...
monkeyposeur Posted December 27, 2012 Author Share Posted December 27, 2012 Maybe this will work. Just connect the ground line coming out of the tcu pin to the power source of the switch, connecting the chassis ground to the ground pin, and not even messing with the accessory pin. I hooked the switch up to a 9 volt battery and the light comes on in this setup. I'll test it out tomorrow and let you know if it works. But I am thinking that there is current coming out of the grounded pin wire flowing to the chassis, so putting the LED switch should still allow it to power up. edit: The reason I want to use this rocker switch is that it looks nice and has a light. All the two pin toggle switches at the auto parts stores didn't have lights and stick out. Link to comment Share on other sites More sharing options...
I Donated broknindarkagain Posted December 27, 2012 I Donated Share Posted December 27, 2012 The lighted switch won't work on a ground circuit.....at least I don't think it will -broknindarkagain My Current Project - Click Here COME AND TAKE IT "The only thing necessary for the triumph of evil is for good men to do nothing." Link to comment Share on other sites More sharing options...
mailman Posted December 27, 2012 Share Posted December 27, 2012 What's the "Power Mode" mod? Sounds cool haha Link to comment Share on other sites More sharing options...
I Donated broknindarkagain Posted December 27, 2012 I Donated Share Posted December 27, 2012 What's the "Power Mode" mod? Sounds cool haha Its where you put a bunch of rice in your gas tank. ....it locks the transmission in a 50/50 torque split -broknindarkagain My Current Project - Click Here COME AND TAKE IT "The only thing necessary for the triumph of evil is for good men to do nothing." Link to comment Share on other sites More sharing options...
Stang70Fastback Posted December 27, 2012 Share Posted December 27, 2012 If anyone figures out how to get this to work, I would literally pay them $15 if they know how, because I've got two lighted toggles for both the FWD and Power Modes on my car, and I can't figure out how to get them working. I can get either the light and no activation of the function, or the function, but no activation of the light, but not both. Link to comment Share on other sites More sharing options...
mailman Posted December 27, 2012 Share Posted December 27, 2012 Its where you put a bunch of rice in your gas tank. Ok, I put 3 cups in, now what? Link to comment Share on other sites More sharing options...
I Donated broknindarkagain Posted December 27, 2012 I Donated Share Posted December 27, 2012 Ok, I put 3 cups in, now what? Wait for VTEC to kick in -broknindarkagain My Current Project - Click Here COME AND TAKE IT "The only thing necessary for the triumph of evil is for good men to do nothing." Link to comment Share on other sites More sharing options...
I Donated broknindarkagain Posted December 27, 2012 I Donated Share Posted December 27, 2012 If anyone figures out how to get this to work, I would literally pay them $15 if they know how, because I've got two lighted toggles for both the FWD and Power Modes on my car, and I can't figure out how to get them working. I can get either the light and no activation of the function, or the function, but no activation of the light, but not both. It can't be done with the switch alone... The only option you have is to add a relay into the circuit. I'll work on a diagram for you. -broknindarkagain My Current Project - Click Here COME AND TAKE IT "The only thing necessary for the triumph of evil is for good men to do nothing." Link to comment Share on other sites More sharing options...
Stang70Fastback Posted December 27, 2012 Share Posted December 27, 2012 Power Mode changes the shift logic (mapping) of the TCU. It's "Sport Mode" with a more aggressive name, lol. EDIT: Brok, I have tried every combination of those three and I have yet to get both the light and whatever feature I am trying to enable to work at the same time. It sucks. Link to comment Share on other sites More sharing options...
monkeyposeur Posted December 27, 2012 Author Share Posted December 27, 2012 Power mode was offered in the JDM SVXs w/4EAT at the push of a button. The USDM 4EATs have the same programming and maps in their TCUs but we didn't get a button. In our TCU harnesses we have an empty pin. All we need to do is ground that pin. SVX guys figured it our first: http://www.rs25.com/forums/f8/99075-4eat-diff-lock-switch-handbrake-mod-torquemada-lite-2.html BBS was next to figure out how to access it in first gens: http://www.rs25.com/forums/f8/99075-4eat-diff-lock-switch-handbrake-mod-torquemada-lite-2.html It is just like stang70 said. It delays the shifting maps which allows you to get to higher rpms before shifting. It also 'listens' to how much you are depressing the throttle. If you are pressing the pedal a lot you can delay the shift to a lower gear and get a sportier experience, lol. The 50/50 split that brok referred to can be wired to a separate switch thusly (you will need to wire in some resistors to make it work): http://www.rs25.com/forums/f8/99075-4eat-diff-lock-switch-handbrake-mod-torquemada-lite-2.html This is not the same mod as the power mode mod. Second gens w/4EAT can also do the power mod. It is a different pin though. Pin #4 in first gens. Link to comment Share on other sites More sharing options...
Tr00b Posted December 27, 2012 Share Posted December 27, 2012 Wire the switch to simple relay like an ignition relay. Instead of the relay closing the switch and applying power to an accessory, have the relay close the switch to ground. I am pretty sure this will work to illuminate your switch and to ground out your pin... Read this for awhile don't see why it won't work. http://www.autoshop101.com/forms/hweb2.pdf Link to comment Share on other sites More sharing options...
Stang70Fastback Posted December 27, 2012 Share Posted December 27, 2012 Wow. I'm an idiot. Never thought of using a relay. Plus since nothing really has any serious current, I could probably use a tiny-ass relay that would fit behind the dash without being a big box thing. I bet that WOULD work. NEW PROJECT! Link to comment Share on other sites More sharing options...
monkeyposeur Posted December 27, 2012 Author Share Posted December 27, 2012 That is exactly what I am thinking will work tr00b. I'll keep reading the pdf. In the meantime if you find a link to a relay let us know! Link to comment Share on other sites More sharing options...
I Donated broknindarkagain Posted December 27, 2012 I Donated Share Posted December 27, 2012 If you get a standard 5 prong relay you should see a diagram on it printed somewhere. Match the diagram to what I have in the image. Depending on teh relay, the numbers on it may change. This is the only way you will be able to do it. Click on the image for a bigger size. Excuse my microsoft paint artwork. basically the way it works is the ground wire coming off the ECU will go through the relay. That side of the relay is like a light switch in the off position. When you send 12v through the other side of the relay, it creates an electromagnet that basically turns the light switch on the other side on (it physically pulls the connection together on the other side). Kind of hard to explain, but it will work. -broknindarkagain My Current Project - Click Here COME AND TAKE IT "The only thing necessary for the triumph of evil is for good men to do nothing." Link to comment Share on other sites More sharing options...
I Donated broknindarkagain Posted December 27, 2012 I Donated Share Posted December 27, 2012 Wire the switch to simple relay like an ignition relay. Instead of the relay closing the switch and applying power to an accessory, have the relay close the switch to ground. I am pretty sure this will work to illuminate your switch and to ground out your pin... Read this for awhile don't see why it won't work. http://www.autoshop101.com/forms/hweb2.pdf I had already said that......lol This is the type of relay I used for my off road lights. It was pretty straight forward. In your case, your pinout would be : 85 - switch 86 - chassis ground 30 - ecu 87 - chassis ground 87a would not be used Just make sure you use low power relays. -broknindarkagain My Current Project - Click Here COME AND TAKE IT "The only thing necessary for the triumph of evil is for good men to do nothing." Link to comment Share on other sites More sharing options...
Tr00b Posted December 27, 2012 Share Posted December 27, 2012 Brok beat me to the relay idea, I just type real slow. (and he called me out on it and I'm slow once again) Why would you need a 5 pin relay to make it work? Does the pin normally get power, then you ground it out instead to get power mode? If it doesn't get power and its just a blank pin, I'd think you could use a 4 pin relay. Or are 5 pin relays more common/easier to get at the parts store? Link to comment Share on other sites More sharing options...
I Donated broknindarkagain Posted December 27, 2012 I Donated Share Posted December 27, 2012 You can use a 4 pin relay....5 pin relays are more common though in automotive. And I answered your question already, you were just slow to type lol the coil side of the relay is the +12v side. When it is energized (via the switch), it will pull the other side closed (ecu ground side) to complete the ground circuit. This keeps the switch on a positive circuit (like what is needed to turn its light on) and still allows that switch to control the ECUs ground. Take a look at the relay picture I posted. When you send live power through 85/86, it literally pulls the diagnal line over (the one between 30/87) to complete that circuit. There is no physical connection between the two sides of the relay. It works via magnet. -broknindarkagain My Current Project - Click Here COME AND TAKE IT "The only thing necessary for the triumph of evil is for good men to do nothing." Link to comment Share on other sites More sharing options...
monkeyposeur Posted December 27, 2012 Author Share Posted December 27, 2012 Brok, what's a low power relay? Thanks BTW. Link to comment Share on other sites More sharing options...
I Donated broknindarkagain Posted December 27, 2012 I Donated Share Posted December 27, 2012 Brok, what's a low power relay? Thanks BTW. Not a problem. Relays are capable of holding x amps of load. For example, I have a 30 amp relay for my off road lights. For what you're doing, you only need a 5 amp relay. You're not going to hurt anything by using a relay rated for more power, so your options are pretty open. I don't know if a 5 amp relay will be cheaper then the higher amp ones. -broknindarkagain My Current Project - Click Here COME AND TAKE IT "The only thing necessary for the triumph of evil is for good men to do nothing." Link to comment Share on other sites More sharing options...
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