Identifying connections on Magnum T56

[sjaroslo]

The shop that put the drivetrain into my car never sent me any of the original paperwork that came with any of the new parts they installed, including the T56. The guys at American Powertrain were nice enough to e-mail me the Installation Instructions, and while those were helpful, they didn't answer all of my questions, therefore, here I am with hat in hand hoping that the shared wisdom of Pro-Touring.com can help me out :)

So, I learned from the instructions that if you're planning on using the electronic speedometer connector on the trans, you should replace the rubber shipping plug for the mechanical speedo with a specific part, so I'm working on procuring that. But I'm also trying to figure out what all of the electrical connections are that are on the unit and where they are all located....

I'm thinking there is the VSS connector, the reverse lights and the reverse lock-out solenoid? Anything else electronic on the trans?

Does my car (67 Camaro with an original 4-speed) expect to have any kind of input provided to it, other than the reverse lights? 4-speed car wouldn't need neutral safety switch input, correct? What about a clutch engagement signal?

Sorry for the crappy pic but here's some of the specifics that I'm confused about. Thanks.

79799

[sjaroslo]

OK, probably answered my own questions with much better quality photos from Tremec's site. Other than the black tube... (which I'm guessing is a vent?).

On the driver's side you can clearly see the rubber stopper on the tailshaft that needs to be replaced if you're using VSS, and the reverse lockout solenoid (interestingly, the instructions tell you to wire this to your brake light, so that the lockout is overridden when you apply the brakes...).

79800

On the passenger side, it looks like the connector under the black tape on my trans is indeed for the backup lights and that would leave the connector on the tailshaft as being the VSS.
79801

Am I seeing correctly that there are TWO drain plugs? One on the passenger side tailshaft and one on the driver's side main body, below the fill?

[67greengt]

I'm going to take a stab at this

Black tube is a vent
Driver's Side rubber plug is if you run a mechanical speedo cable
Driver's Lockout as you've mentioned
Passenger Side T/S if a sensor to run an electric speedo (I believe its your signal wires)
Passenger Side Electrical connection is for your backup lights
To hazard a guess I would think the tailshaft is for the drain, the body is for the fill

[parsonsj]

The rubber plug is just for shipping. You need to source a real block-off there if you aren't running a mechanical speedometer. You can leave the reverse shift inhibit solenoid disconnected. It inhibits shifting into reverse if powered, and is not active if not powered.

[sjaroslo]

Thank you for the feedback!

[BonzoHansen]

IMO brake pedal is not the best option for RLO. It engages too much and allows you to try to shift to reverse at speed. I ended up mounting a small momentary switch under my dash.

[jamier2]

You can leave the reverse shift inhibit solenoid disconnected. It inhibits shifting into reverse if powered, and is not active if not powered.


IMO brake pedal is not the best option for RLO. It engages too much and allows you to try to shift to reverse at speed. I ended up mounting a small momentary switch under my dash.

Am I reading this wrong or are these two people saying exactly opposite things?

If reverse is not blocked when not powered, as Parsons says, wouldn't wiring it to the brake pedal stop you from going into reverse?

I need to wire mine up soon and want to clarify a bit. I am thinking about getting a shifter ball that has a small momentary switch build in (like for a roll control / line lock). That is, unless Parsons is correct then I'd just leave it alone? How much real risk of hitting reverse (I assume it's only a risk when going from 4th to 5th - and in my 09 Z06 with similar trans it was a long long way from 5th to reverse)?

[jamier2]

Duplicate post

[jamier2]

So, I learned from the instructions that if you're planning on using the electronic speedometer connector on the trans, you should replace the rubber shipping plug for the mechanical speedo with a specific part, so I'm working on procuring that.

Any info on where I can get one of those? I am in the same position.

[sjaroslo]

Jamier, I actually found someone on Lateral-G, I think, who had one for sale.... I think I searched on the part number; if I didn't post the part number in any of my threads, let me know and I'll try to find it again for you.

Taking a stab at your observation about the RLO, I'm guessing that once electricity is applied to the switch, then reverse is locked out. Interrupting that electricity (either through a switch or, at the extreme, never even applying electricity in the first place), allows the trans to shift to reverse. Although you are right, that wouldn't make sense to use the brake light switch to drive it....

[jamier2]

Jamier, I actually found someone on Lateral-G, I think, who had one for sale.... I think I searched on the part number; if I didn't post the part number in any of my threads, let me know and I'll try to find it again for you.

Taking a stab at your observation about the RLO, I'm guessing that once electricity is applied to the switch, then reverse is locked out. Interrupting that electricity (either through a switch or, at the extreme, never even applying electricity in the first place), allows the trans to shift to reverse. Although you are right, that wouldn't make sense to use the brake light switch to drive it....

Thanks for the quick reply. I finally googled correctly and happened to find an eBay listing from Keisler for the Tremec part # 30-360-1X. They had it for under $35 including shipping. I know I've seen them listed at places for over $40 so I can't complain.

I still can't imagine the RLO isn't defaulted in the no-power state to block reverse. Just doesn't make sense to me to be otherwise. I am going to stop by and grab some bolts to attach my shift lever today and I'll see if it freely goes in reverse. I guarantee this one hasn't ever been powered so I should know for sure.

[jamier2]

...about the RLO, I'm guessing that once electricity is applied to the switch, then reverse is locked out. Interrupting that electricity (either through a switch or, at the extreme, never even applying electricity in the first place), allows the trans to shift to reverse. Although you are right, that wouldn't make sense to use the brake light switch to drive it....

Well, I can guarantee you that is not the case with mine. Mine has never been plugged in and reverse is definitely locked out. Tried it yesterday. While I can get it to shift to reverse, it's very difficult.

I'm going to run some switched power - whether its on brake light, button on shifter, or whatever.

I did find a device that sends the signal automatically when the speed isless than 3mph. Neat but probably too much trouble.

[Mkelcy]

Your intuition is correct. The RLO has a VERY heavy spring preventing casual shifting into reverse. If you apply power, a solenoid compresses the spring. Wiring the RLO to brakes activates the RLO solenoid when, for example, braking and downshifting.

[AMC Racer]

I wired the RLO solenoid to the brake light switch and added a toggle switch in series on the console. Console switch must be on and brake pedal pressed to shift into reverse.

[Samckitt]

The rubber plug is just for shipping. You need to source a real block-off there if you aren't running a mechanical speedometer. You can leave the reverse shift inhibit solenoid disconnected. It inhibits shifting into reverse if powered, and is not active if not powered.

Unless this is different than OEM, the solenoid is always closed & the gate to reverse is blocked unless there is power to it. There is a spring on it that can be over powered & pushed into reverse. The gate is opened only when powered.

Found some info on the circuit from: http://www.hotrodlane.cc/New%20LT%20Tech%20Page/LT%20DTC%20Codes/DTC%20P1667%20Reverse%20Inhibit%20Solenoid%20Contr ol%20Circuit.htm

Circuit Description

Ignition voltage is supplied directly to the Reverse Lockout solenoid. The PCM controls the solenoid by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component ON, the voltage of the control circuit should be low (near 0 volts). When the PCM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high (near battery voltage). If the fault detection circuit senses a voltage other than what is expected, the fault line status will change causing the DTC to set.

When the Reverse Lockout solenoid is energized, the transmission can be shifted into reverse. The PCM enables the Reverse Lockout solenoid whenever vehicle speed is below 5 mph. When vehicle speed is above 5 mph, the PCM will de-energize the solenoid, which will prevent the transmission from being shifted into reverse.

[jamier2]

Not to hijack, but does anyone know what size bolts are used to attach the shift handle? I've bought metric 8, 10, and several standard bolts but nothing I've tried will fit?

[Samckitt]

Not to hijack, but does anyone know what size bolts are used to attach the shift handle? I've bought metric 8, 10, and several standard bolts but nothing I've tried will fit?

3/8-24.

[CarlC]

If you're using a GM EFI ECM it should have a reverse lockout circuit.

[TheJDMan]

On the T56 Magnum, the reverse is locked out by a heavy spring when the RLO solenoid is un-powered. When you energize the RLO solenoid it compresses the spring allowing easy reverse shift. Wiring the RLO circuit to the brakes is a mistake IMO. Every time you apply the brakes the RLO solenoid is energized whether you are shifting to reverse or not. That creates a lot of unnecessary cycles on the RLO system and can potentially allow accidental reverse. IMO, a better idea is to use a shift knob equipped with a roll control button to control the RLO. That way you can energize the RLO and your hand never has to leave the shift knob.

[parsonsj]

I hear what you are all saying, but I don't think putting my most recent project into reverse takes that much effort, and the solenoid is disconnected. I'll have that car back for some minor maintenance in a few weeks, and I'll investigate it some more.

[parsonsj]

And I'm with Carl: if you're using a GM ECM that's definitely the best method if you want to use the RLO.

[TheJDMan]

John,
You are correct that it does not take that much effort to shift to reverse without the RLO energized. BUT, it takes NO effort to shift to reverse WITH the RLO energized.

[jamier2]

3/8-24.

Thanks. Worked perfectly.

[jamier2]

I really like the idea of the ECM control. I don't think that will work for me, though. My ECM does have a speed input connection (that doesn't match my T56 Magnum VSS plug). I'll have to recheck, but I don't think there is an output on mine for the RLO control. Mine is the GMPP LS controller kit so it may be different.

[parsonsj]

The GMPP LS controller might need a wire added to the harness and be re-programmed, but the pin is there.

[parsonsj]

You are correct that it does not take that much effort to shift to reverse without the RLO energized. BUT, it takes NO effort to shift to reverse WITH the RLO energized.Thanks Steve. I just went to my shop tonight and tested this on this year's project (LS9/T56 Magnum/69 Camaro). The car is nowhere near done, but the drivetrain is in the car. I bolted up a makeshift shifter handle about 12" long and found shifting into reverse to be no big deal. Definite extra pressure required (which is good so you don't go from 4th to Reverse on the highway), but no more than either of my son's Mustangs.

So the RLO is a feature than can be omitted if you want, but the way to go is to connect it to the ECM if you want it.

[jamier2]

The GMPP LS controller might need a wire added to the harness and be re-programmed, but the pin is there.

I might look into that. I wish I could just find a nice shift ball with a switch so I could make this easy. I know there are quite a few out there - looked at and talked to the guys from Hurst today at the LS Fest, but I would like one that has the T56 shift pattern on it too...

I guess I'm too picky. :)

.... and apparently too lazy to search. I found this just now. http://www.nookandtranny.com/mm5/merchant.mvc?Screen=PROD&Store_Code=NookandTranny&Product_Code=HUR-1630052&Category_Code=INTSK I just need to search for a shift handle for my Chevelle that will work with it.

[jamier2]

Well this is funny. I even talked to the Hurst guy today at their display at the LS Fest and he looked in his book (pamphlet to be fair) and said "nope, we don't make a 6 speed pattern shifter with a switch."

Found this just now:http://www.summitracing.com/parts/huu-1630052/overview/

Exactly what I needed.

[sjaroslo]

Edit: I'm a doofus. Looks like I wired the cars backup lights to the solenoid connection rather than the backup lights connection, at least it looks that way on the surface. Hopefully, problem solved.


Resurrecting an older thread but it is MY thread so I think that it is OK?? :-) Now that the car is sort of running, I'm having a weird experience. With the car off, I can definitely feel the heavy spring that prevents accidental engagement of reverse. However, with the car running, the trans slips into reverse with ease--TOO much ease, I would be very scared about accidentally doing something very bad at speed. BUT, I don't have anything hooked up to the reverse lockout solenoid wiring! I'm going to crawl underneath there in a few minutes, just to make sure that I haven't wired up something stupid, but this seems very, very strange to me. Any thoughts? Thanks.

[icemanrd19]

you have to have something hooked to it or you wouldn't see a difference.

[68Cuda440]

Do you happen to have the part number of the transmission you have? There are 4 versions... I would assume, and be fairly certain, you either have the "GM" close ratio or the "GM" wide ratio. But, make sure. The "Ford" version LSS output is different than the "GM" version.

[TheJDMan]

Just to follow up, this is the 6 speed shift pattern knob w/line lock button I'm using.

http://www.speeddawg.com/pro-white-black-6-speed-shift-knob-with-line-lock-nos-button/

[minendrews68]

You could also use the Hurst T-handle with the Line-Loc switch. I just think the ball with the 6 speed logo is a better fit for this transmission. I guess it just depends on the individual. I connected mine to the brake lines, but I am going to change to the ball because I agree, that is cycling the RLO to much in my opinion.

[TheJDMan]

Carl,
It's funny, I actually have a Hurst T-handle w/line lock button but I did not like that handle with the T56. I tended to grip the handle too tight which caused me to miss a lot of shifts. I like the ball much better, I grip it lightly with three fingers and a lot less missed shifts.

[sjaroslo]

Do you happen to have the part number of the transmission you have? There are 4 versions... I would assume, and be fairly certain, you either have the "GM" close ratio or the "GM" wide ratio. But, make sure. The "Ford" version LSS output is different than the "GM" version.

Yeah, it is the TUET11009, which I believe is the LS close ratio unit. Thanks,

[sjaroslo]

Just to follow up, this is the 6 speed shift pattern knob w/line lock button I'm using.

http://www.speeddawg.com/pro-white-black-6-speed-shift-knob-with-line-lock-nos-button/

Is there any way to dress up the wiring that runs down the handle?

[minendrews68]

Carl,
It's funny, I actually have a Hurst T-handle w/line lock button but I did not like that handle with the T56. I tended to grip the handle too tight which caused me to miss a lot of shifts. I like the ball much better, I grip it lightly with three fingers and a lot less missed shifts.

I used to really like the Hurst T-handle, I bought one for this build and was going to use it for my Line-Loc. Now it sits in my tool box and I'm using the stock shifter for my T-56. Gotta get me the ball knob.