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2G Wiring relay for launching in 2nd gear

v8s_are_slow

Proven Member
2,644
183
Sep 30, 2002
Panama City, Florida
Was talking to someone on Facebook about it but can't remember who it was. I know you can stage in 2nd gear and as soon as you let off the brakes it'll switch to 1st. You have to wire in a relay to do it. But not sure how to wire it in.

I know to be in first, power is supplied to solenoids A and B.
To be in 2nd, power is supplied to B only.

So this means when hitting the brakes to stage in 2nd gear, I need to cut the power to solenoid A with the relay. Problem is, I don't know how to take the power away. I can see it being easy to add the power. But killing the power??? Help anyone??? Thanks!

P.S. I'm terrible at wiring so if anyone knows how to do it, breaking it down to make it elementary would be GREAT!!! Like for example, wire pin 35 to ground. Pin 36 at relay to power, and so on and so forth.

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randman2011

Proven Member
458
208
Feb 26, 2012
Indianapolis, Indiana
Electrically, you'd just put an NC (normally closed) relay inline with power to solenoid A so when you energize the relay by supplying power from a switch, it opens and cuts the connection to A. Most relays have a NO (normally open) AND NC (normally closed) pole so you can get any regular relay and make it work.

That said, I know nothing about automatic transmissions or controlling them. So I'm taking your info at face value.

EDIT: I assume the purpose of this is to put less torque to the wheels while staging so you need less brake to stay put? Or to put more load on the engine or lower the RPMs? I know so little about drag racing.

EDIT2:
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Here's a "typical" 5 pin relay that you'd find labeled as automotive at Autozone or whatever. Pins 85 and 86 are the coil, so you'd hook one side up to +12V and the other to a switch to ground (or ground and then +12V; doesn't matter). Put a fuse in the line to 12V if you take power straight from the battery! 87a is the normally closed circuit, so you'd stick pins 30 and 87a in the middle of whatever wire goes to Solenoid A. Leave 87 disconnected but depending on how you mount the relay it might be good to insulate it.
 
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Tyeler18

Proven Member
2,362
125
Dec 16, 2008
Casa Grande, Arizona
Use this wiring diagram but substitute dsm solenoids.


I use this to foot brake my montero into boost. I can’t even get near boost on just the foot brake without it burning the back tires off. On the “trans brake” I have no issues building 5-6lbs within 5 seconds in 3rd and can definitely make more if I sit on it longer, but I’ve rolled one truck being a dumbass like that so I’m afraid of seeing how much boost it’ll make LOL
 

Bud92gsx

Welcome Wagon
22,725
236
Jan 16, 2008
Wisconsin, Wisconsin
Are you wanting to launch in 2nd because the brakes won't hold? You could get a restalled converter, im just curious what brings on this thread?

The old solenoid on off thing. I used that for years with my home made auto shifter
 

v8s_are_slow

Proven Member
2,644
183
Sep 30, 2002
Panama City, Florida
I'll look at the replies later when I get a chance (working at the moment), but thanks for the replies.

But yes, trying to "stage" in 2nd, 3rd, whatever so that there's not so much torque being applied to the axles (unlike a manual car where the clutch is pushed in and no torque being applied until letting out and the car is moving forward). With an auto, torque is always being applied to the axles as long as you're in drive. Staging in 1st puts a lot of torque on the axles and can snap them when brakes are applied (anyone who watches the Joe Wrenches channel on YouTube knows that Joe Bucci did just that) or push through the brakes. The axles want to turn, and you're trying to stop them from turning with the brakes and can end up twisting/snapping them. So to make it easier, you stage in 2nd (or might try 3rd). When you hit the brakes, you should have a relay to cut the power to the solenoid that puts you in another gear and as soon as you left off the brakes, it'll go into 1st instantly out of the hole without missing a beat. I've just gotta figure out the best way to wire it up is all.

P.S. I have a Precision #6 from Jeff Bush so my converter should definitely be more than enough to handle the job. Just need to be in a different gear while staging is all.
 
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DSMPT

DSM Wiseman
1,747
1,308
Jun 12, 2014
Japan / Mexico, Arizona
I am not a auto person, so I could be wrong but I can't be sure if the simple 5 pin relay method (switching 1st and 2nd by brake) would work in this case. Besides the brake, it should have one more parameter to control the relay such as VSS signal. Otherwise any time hits the brake, it would go into 2nd gear. Isn't that risky if that happens in higher gear at high rpm?
I believe to control through ECU would be the best but if ECU has no output available anymore, I may try a switching controller. Like Greddy dual switching controller. That would externally allow you to set more than two parameters to activate (ground) one or two relay.
 

Tyeler18

Proven Member
2,362
125
Dec 16, 2008
Casa Grande, Arizona
To add to my setup, I use the cruise "set" button to engage my brake. I have a way overcomplicated setup in my truck since I have cruise control still, but basically with the cruise turn "on" it becomes normal cruise functions, when I turn cruise "off" a 5 pole relay activates my brake relay which is then controlled through the "set" button on the stalk, so mine is only active while holding set. The wiring diagram I have posted uses a momentary switch to toggle it.

This was discussed on the ecmlink page, as my 4l80 has a good 2 second delay from release before fluid applies first and you're moving. If it isn't timed well it'll bog the launch, I discussed triggering off the brake switch with another guy on his dsm and he claims the brake switch was still fast enough for his trans to hit 1st without dropping load, on my truck there's no way it would react fast enough, so id take that with a grain of salt. The momentary switch works way better for me.
 

v8s_are_slow

Proven Member
2,644
183
Sep 30, 2002
Panama City, Florida
I am not a auto person, so I could be wrong but I can't be sure if the simple 5 pin relay method (switching 1st and 2nd by brake) would work in this case. Besides the brake, it should have one more parameter to control the relay such as VSS signal. Otherwise any time hits the brake, it would go into 2nd gear. Isn't that risky if that happens in higher gear at high rpm?
I believe to control through ECU would be the best but if ECU has no output available anymore, I may try a switching controller. Like Greddy dual switching controller. That would externally allow you to set more than two parameters to activate (ground) one or two relay.
I'm using Ecmlink and setting it up so that this ONLY happens during set parameters. If I'm over a certain speed, etc. this gets disabled anyway.
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To add to my setup, I use the cruise "set" button to engage my brake. I have a way overcomplicated setup in my truck since I have cruise control still, but basically with the cruise turn "on" it becomes normal cruise functions, when I turn cruise "off" a 5 pole relay activates my brake relay which is then controlled through the "set" button on the stalk, so mine is only active while holding set. The wiring diagram I have posted uses a momentary switch to toggle it.

This was discussed on the ecmlink page, as my 4l80 has a good 2 second delay from release before fluid applies first and you're moving. If it isn't timed well it'll bog the launch, I discussed triggering off the brake switch with another guy on his dsm and he claims the brake switch was still fast enough for his trans to hit 1st without dropping load, on my truck there's no way it would react fast enough, so id take that with a grain of salt. The momentary switch works way better for me.
Just to be clear, this isn't for clamping the brakes down to keep from moving forward. I have a vacuum pump for that. I need to cut power to the solenoids so that it's in 2nd or 3rd gear while staging. There's 2 solenoids in the transmission. If both are powered, it'll be in 1st gear. Disable one and it's in 2nd gear. Take power away from both solenoids and it's in 3rd gear. The trick is to set it up so that when the parameters above are met, the relay gets triggered to remove the power ONLY when hitting the brake pedal. Reading your comment again, I think you understand what I'm saying. I just suck at wiring and relays. I hate it with a passion.
 

Bud92gsx

Welcome Wagon
22,725
236
Jan 16, 2008
Wisconsin, Wisconsin
Allright so ill drop a little knowledge ive been sitting on.
Evoscan will control i know for sure the evo 7 auto trans. Umm I myself have been looking into getting the evo 7 ecu getting the jumper harness and trying to figure out how to use that ecu and evoscan to control our dsm trannies. But im poor so it may take me a while to get what I need b4 I unleash what I find to our community. Thats my plan anyway
 

Tyeler18

Proven Member
2,362
125
Dec 16, 2008
Casa Grande, Arizona
Just to be clear, this isn't for clamping the brakes down to keep from moving forward. I have a vacuum pump for that. I need to cut power to the solenoids so that it's in 2nd or 3rd gear while staging. There's 2 solenoids in the transmission. If both are powered, it'll be in 1st gear. Disable one and it's in 2nd gear. Take power away from both solenoids and it's in 3rd gear. The trick is to set it up so that when the parameters above are met, the relay gets triggered to remove the power ONLY when hitting the brake pedal. Reading your comment again, I think you understand what I'm saying. I just suck at wiring and relays. I hate it with a passion.
I'm aware of what you're trying to do, if you're trying to use it like a trans brake though there's going to be a delay when you release the brake and take off. You'll be leaving in 2nd until the hydraulic path is complete and the trans completes the down shift. If I leave in my truck before it completes the down shift the truck falls out of boost and onto it's face. I use mine solely to build boost on the foot brake which in turn allows me to use less brake to stage, I assume that's essentially what you're trying to do unless you plan to actually leave in 2nd and ignore 1st?
 

1990TSIAWDTALON

Moderator
8,573
4,476
Nov 14, 2013
Independence, Kansas
Tyeler is correct about the delay in getting back to 1st. I played with my SmartShift box and could get it to stage in 2nd (so I could hold her back) and then go to 1st when I got off the brake. There is a half second delay in that gear change back to 1st (well definately a delay). Shortly after I figured the thing out, my car decided to quit running so thats as far as I got.
The setup does work but I know of a person using it that had an issue with it staying in 2nd for the launch (and he still ran a 10). It was in a Eagle Summit.
Just my 2 cents on the subject.
Marty

Edit: I found Shawns reply to me about "stallup mode" on the SmartShift box, which I attached.

"Stall up mode explained

The stall up mode requires:
*working/connected throttle position sensor
*brake switch
*RPM or speed signal (both preferred)

Simply configure the window you want stall up mode to be active. The default values should work but you might need to adjust the RPM values for your setup. Make sure the enable check box is checked, make sure while brake switch active is checked, and check hold 2nd gear while active box. That’s all that is necessary. When ALL conditions are met, which they should be if you are sitting still WOT and on the brake and RPM is in the window it will automatically select 2nd gear. The display will not reflect it unless you are using one of the standalone displays that read actual solenoid outputs. As soon as the brake is released or vehicle speed exceeds the max MPH value it will revert back to 1st gear instantly."
This is only if you are using a SmartShift shift box from ForcedFour.com, but I thought it fit in this thread for information purposes.
 

DSMPT

DSM Wiseman
1,747
1,308
Jun 12, 2014
Japan / Mexico, Arizona
I'm using Ecmlink and setting it up so that this ONLY happens during set parameters. If I'm over a certain speed, etc. this gets disabled anyway.
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That's what I meant above if you still have an available output.
Doesn't this work?
Relay 85 - ECMLink output
Relay 86 - Ground
Relay 30 - 12V
Relay 87a - Solenoid +
Relay 87 - Not connected
 

v8s_are_slow

Proven Member
2,644
183
Sep 30, 2002
Panama City, Florida
That's what I meant above if you still have an available output.
Doesn't this work?
Relay 85 - ECMLink output
Relay 86 - Ground
Relay 30 - 12V
Relay 87a - Solenoid +
Relay 87 - Not connected
Honestly, I'm not sure. Hoping you could tell me. Lol.
 

DSMPT

DSM Wiseman
1,747
1,308
Jun 12, 2014
Japan / Mexico, Arizona
And do you mean like this?

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No no, I meant that this one with brake switch may be risky and it should have one more thing between the brake pedal and the relay. Maybe like a momentary switch etc.
And I said "That's what I meant above" in my 2nd comment meant it would be better if you have an available output with your ECU and use it instead of brake switch alone.
I meant,
Relay 85 - ECU Pin #3 (ECMLink Fuel solenoid activation)
Relay 86 - Ground
Relay 30 - 12V
Relay 87a - Solenoid +
Relay 87 - Not connected

I am not a auto person, so I can't be sure if this is what you exactly need. This is just to On/Off for a solenoid.
 

1990TSIAWDTALON

Moderator
8,573
4,476
Nov 14, 2013
Independence, Kansas
It may be exacly what the OP IS wanting. After going thru the switching and such, there is a delay that is not what is needed in a drag race situation.
I think your idea is good Bobby, but I understand your concern for the trans.
All the switching may seem small but when it all adds up, you get a delay in going back to 1st. If we can hold it in 2nd (or 3rd) and instantly go to 1st, that is the desired outcome if I understand the thread correctly.
I will add that the "brake" switch "could" be a push button on the steering wheel like my setup. As soon as it is released, it goes to 1st. Just a thought.
 

v8s_are_slow

Proven Member
2,644
183
Sep 30, 2002
Panama City, Florida
To be clear, I believe I misspoke earlier when talking about the operation of it as though ecmlink is controlling this. Ecmlink controls when my nitrous is on/off, and when my secondary maps are on/off. I would just want my brake switch to follow suit and do the gear switching under the same parameters as the nitrous.

I'm unsure of how long the delay would be (because I've never done this) but just going off what I've heard others doing. Due to this post talking about staging in 2nd or 3rd, I made a Facebook post on the group for auto dsm's, asking what other folks are staging either 1st, 2nd, or 3rd gear. Most are saying 2nd. Some are saying 1st and to just kill torque being applied by pulling timing. I'm already doing that but guess I'll have to just see how it performs before trying to switch gears and maybe come back to this. If there's a delay, this won't be any good for racing. Dunno yet. Hmmm....
 

DSMPT

DSM Wiseman
1,747
1,308
Jun 12, 2014
Japan / Mexico, Arizona
Ah so aside from the delay like Tyeler and Marty mentioned, what you want to try is to synchronize the solenoid A OFF with the nitrous solenoid/secondary MAP ON and vice-versa? If that's the case what I said above won't work.

How about like below? Technically while nitrous solenoid is ON via ECMLink, the connection from TCU/shift box to the solenoid A would be cut by the relay. And once nitrous solenoid is OFF, the connection to the solenoid A would come back. (Physically cut the connection to the solenoid A, so I am not sure maybe it would cause some error in TCU?)

Relay 85 - ECU Pin #3 or #6 (Fuel or EGR solenoid that is used to control nitrous solenoid)
Relay 86 - Ground
Relay 30 - Wire from TCU or shift box to Solenoid A
Relay 87a - Solenoid A
Relay 87 - Not connected
 
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v8s_are_slow

Proven Member
2,644
183
Sep 30, 2002
Panama City, Florida
Well, to add to this, I'm using the wiring for the fpr solenoid to a relay to trigger the nitrous solenoid. I'm currently using a 75 dry shot but might bump to 100 if needed. Trying to roll out to around 30 mph or so out of the hole until the nitrous shuts off to keep the momentum going. Using an old forced four shift box and/or a B&M shifter for shifting duty. Vacuum pump works only when nitrous is turned on, which should also apply to the 2-1 shift. No tcu.

Not sure if this makes a difference in wiring.
 

DSMPT

DSM Wiseman
1,747
1,308
Jun 12, 2014
Japan / Mexico, Arizona
I'm using the wiring for the fpr solenoid to a relay to trigger the nitrous solenoid.
Yes I am aware of that. I don't know how you wire the shift box but what I meant above is like this. Or maybe sandwich the relay in the solenoid ground wire.

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v8s_are_slow

Proven Member
2,644
183
Sep 30, 2002
Panama City, Florida
Thanks! I'll test this out and post results when I have them. Maybe in a couple of weeks or so. Feel free to reply here for a reminder if I happen to forget and you're someone reading this.
 

Tyeler18

Proven Member
2,362
125
Dec 16, 2008
Casa Grande, Arizona
It may be exacly what the OP IS wanting. After going thru the switching and such, there is a delay that is not what is needed in a drag race situation.
I think your idea is good Bobby, but I understand your concern for the trans.
All the switching may seem small but when it all adds up, you get a delay in going back to 1st. If we can hold it in 2nd (or 3rd) and instantly go to 1st, that is the desired outcome if I understand the thread correctly.
I will add that the "brake" switch "could" be a push button on the steering wheel like my setup. As soon as it is released, it goes to 1st. Just a thought.
This is where a real trans brake would be nice, since you're locked in 1st and reverse the hydraulic path to first is already completed. No delay :D although thats a little harder in a dsm trans
 
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