L67 T56 Swap Guide

[Mr Tippins]

Link Section

VT - VY Workshop Manual
VT - VY Workshop Manual
VT - VY Workshop Manual
Rev Hang / Idle Follower Just Commodores

Getting Started PCM hacking
NVram
ALDL Interface connector
ALDL simulator
Envoyous Customs Body Diagnostics Software

Malwood adaptor plate
Dellows Bell housing
T56 Connector Kit

Alright, I’ve recently gone over my T56 swap in my VY l67 and solved a few issues I haven't seen covered anywhere and thought I’d write up some information about it for anyone trying to do a manual l67 swap.




Hardware

Now it has been a while since I did the actual swap (like 4 years) but from the top of my head this is what you will need on the hardware side of things. This stuff has been covered by a lot of people in a lot of places, there’s videos about it on youtube and lots of discussion on various forums. I figured I should include a high level list anyway.



*Needed*
-NPC custom clutch for T56 to Holden V6. Contact NPC for a custom clutch
-V6 manual starter motor (Auto 4l60e doesn't fit), I believe from the older T5 gearbox, not the getrag 5 speed found in the VT onwards. Buy from any auto shop / ebay
(Image from ebay listing)

Correct Starter Motor

Starter Picture.png (539.36 KiB) Viewed 9195 times

-Malwood adaptor plate OR Dellow bell housing (You’ll have to contact dellows to see if they still stock it)
-Dowels for Crankshaft (I put a dowel in the balancing hole ), You may need to drill the crank.
-Cross-member, Custom from Malwood (If they still make it) OR drill holes in your old one.
-Gearbox mount, factory T56 mount.
-Shorten the Driveshaft
-Pedal box (Bolts straight in, just remove the gromet in the firewall), comes with a clutch pedal and smaller brake pedal. There's a foam lining under the fuse box that is different from the auto as well.
-Clutch Master Cylinder
-Clutch Slave Cylinder
-Hydraulic Lines (Can't remember specs), you’ll need to get one made up at a shop to join to the hardline off the T56
-Gear stick and boot
-Gear stick internal rubber boot and plate.



*Recommended*
-Bleeder hose (You will thank yourself when your heavy duty clutch ruins your Master Cylinder and you need to bleed it 3 years later), comes with the malwood T56 slave cylinder
-Manual Radiator
-Rear Main Seal, It’ll save you down the line
-Gearbox output seal
-Gearbox oil change
-Gearbox short shifter, be careful mine fouled on the body where it pokes through into the cabin.
-Brass shifter linkage cup
-New tailshaft donut bushing (install correct orientation)
-Shorten Diff ratio (I went with 4.11:1 runs 1700rpm at 100km/h). Table is @100km/h or @2000rpm, wheels are 265/35 R18

Differential Chart

MGdjsii.png (120.16 KiB) Viewed 9195 times

*Notes*
4l60e output splines same as T56.



Wiring

Now this is the section I’ve spent a bit of time looking into (and the tune), there isn’t as much information on this section, that I could find, especially when I was doing the swap. So a list of things you’ll need to do. I would recommend buying the T56 Connector Kit from EFI Hardware.

I’ve decided to include a bit of information here about implementing an aftermarket PCM to work in VT – VY commodores, I strongly considered binning the delco when I got to figuring the wiring and tuning out haha. I’m not going to go into all the run of the mill problems you will face running an aftermarket PCM such as tuning the engine on a haltech or something and all the tribulations you’ll face when creating a loom from scratch. I will go over the issues unique to the VT – VY commodore when you remove the factory PCM. These being that the BCM and Dash will have a cry and throw a bunch of codes.

The solution I found that deals with this is the ALDL simulator made by one of the guys on this forum. It has a mode that enables it to simulate the BCM. It takes data from the aftermarket PCM to control things like the reverse lockout solenoid or radiator fans when the AC is on. Have a read of the manual that is provided on the website for a full understanding.

Note
Wiring diagrams are taken from the official workshop manual linked above, under the VY series 2 service manual “MY 2004 VY and V2 Series Wiring Diagrams”



Clutch Pedal Patch Harness

You will need to install a factory patch harness which will disengage the cruise when pressed, there are no mods needed, it just plugs straight into the brake pedal harness plug.

(Image from sheet 20 of 140)

Clutch Pedal Patch Harness

PWR and Traction Control

The new manual shifter will mean you have to relocate the PWR and TC switches, there is a spot for them in front of the glove box. Just unplug the PWR switch and remove the patch loom, if PWR mode engages for whatever reason (Icon on the dash) just pull the negative off the battery and do a power cycle, this will disengage it.

(Image from sheet 28 of 140)

Traction Control Switch Diagram

Traction Control Switch Location

Reverse Lights

This will be the Brown / Blue and Green wire, These will need to be extended and terminated with the T56 Reverse Sensor Plug

(Image from sheet 77 of 140)

Reverse Light Diagram

Reverse Light Location

Vehicle Speed Sensor (VSS)

The plug and wiring is the same between the T56 and 4L60e they just use different sensor internals, just plug in the existing connector into the T56 sensor.
T56 Speed Sensor Plug



Reverse Lockout Solenoid

There are a few ways to go about dealing with the reverse lockout solenoid. The easy ways are to just remove it and plug the hole (Google T56 Reverse lockout blanking plug) or not touch it at all. It is weak enough to just overpower with brute force every time you need to use reverse.

Another solution is to wire it into the brake switch circuit, when you press the brake it will disengage.

What I did initially was to use a frequency switch from jaycar, using the chopped wires from the auto transmission.


Signal input (Green) > VSS output, I used the Low output (Blue / White), D1 on the V6 PCM (Sheet 24) or D5 on the S/C V6 PCM (Sheet 25)
DC 12V + (Red) > 12v from Transmission fuse (Pink / Blue)
DC 12V – (Black) > Ground wire in the PCM loom (Black / Red)

COM 1 or 2 (Brown) > Ground, 12V or the lockout solenoid
NO 1 or 2 (Blue) > Ground, 12V or the lockout solenoid

(Image from Jaycar website)

Jaycar Frequency Switch diagram

X7OfnnC.png (110.63 KiB) Viewed 9189 times

Neutral safety switch

This is just to get the car to start. The neutral safety switch will stop the car from starting if the car is not in park of neutral in an automatic application. It needs to be bypassed as per the factory wiring loom.

Connect:
X206 Grey (pin 1) > A84 (pin A8 V6 or F5 S/C V6 ) Grey / Blue

(Image from sheet 8 and 113 of 140)

Neutral Safety Switch Diagram

Tune

Okay the tuning section, this is the part that I see most talked about on this forum and I haven’t been able to find a consolidated solution, so here is my take.

There is a bit of setup needed to begin tuning a Delco. This forum is full of information on how to do this. I plan on making a quick but comprehensive guide / checklist on how to set everything up as the information here is a little bit spread out. If I get around to it I will link it here. For a VT- VY you will need to buy:

NVram Setup
ALDL Interface Connector
Getting Started PCM Hacking

Once you have everything setup the changes that need to be made are listed below.



Adjust throttle follower values

The tables you want to adjust are
IAC – Throttle Follower Gain vs RPM
IAC – Throttle Follower Gain vs KPH (The RPM and KPH tables reference the same memory address)
IAC – Max Throttle Follower Steps vs RPM
IAC – Max Throttle Follower Steps vs Vehicle Speed (The RPM and Vehicle Speed tables reference the same memory address)

This will fix all the rev hang issues that are present, I’ve seen a lot of posts about this and it took me ages to find out how to fix it. I was advised by Rhys from RKGarage

IAC Bin Modifications

MT flag

VSS Option – Set = Manual Getrag
Manual Trans – Set = MT

The MT flag disables all the auto related BTC’s throw codes and I’m not sure what the VSS option flag does.

MT Flag Modifications

VSS calibration

VSS Ratio – Speed Constant for Automatic Transmission.

This will just calibrate the PCM speed input allowing speed dictated events to trigger correctly, examples like shift tables in to automatic settings. I don’t think this will actually impact the a manual tune at all, it’s just nice for logging. The only parameters that rely on the speed of the vehicle (that I can find) are related to the transmission.

VSS Bin Modifications

Dash

Someone has already made a tutorial on how to do this on Just Commodores, everything is explained there.

It is worth noting here that I attempted to use a speedo corrector from jaycar and I had some serious issues with an unstable readout because of it. This resulted in my cruise control being very jerky, potentially an option if you don’t care about that.

Envyous Customs Body Diagnostics Tools has a lot of other options you can play around with, it’s worth a look if you care about that stuff, I turned on police mode for a digital speedo and disabled the PRND123 at the bottom of the display (Manual Mode). You can setup a custom startup image as well if you want to.

That’s pretty much the “how-to” on manual L67 vehicles in a VT- VY chassis. This is kind of the widely accepted way to do it based on my research. I ran my car like this for years; however, you will notice after you follow all these instructions you will still have a couple issues.

The issues you’ll run into is:

A) Cruise Control
Cruise control won’t work below 70 km/h and will change speed at ~3-4 km/h at a time instead of 1.

B)Traction Control
Simply, the traction control won’t disengage and I believe by extension the ABS doesn’t work (didn’t test it however)

This is what has caused me to re-look into all this stuff and write this guide, the cruise control issue was driving me crazy and I don’t think you can pass the pits with dash-lights / without traction control/ABS working correctly. I have since solved both of these issues and will include the solutions in part 2.

[Mr Tippins]

Part 2... The 10%

Now the whole reason I’m here writing this is because the issues I mentioned in solution 1 reaaaaally started to annoy me so I decided to figure something out to solve those few issues.

Starting with the cruise issue.

As stated, the symptoms are that the cruise does won’t engage under 70 km/h and will adjust in intervals of about 3 km/h.

I narrowed this down to the smaller amount of teeth on the reluctor wheel inside the T56. The T56 being 17 tooth and the 4l60e being a 40 tooth. You cannot calibrate the PPK number inside the body control module resulting in the cruise control having essentially low resolution. Funnily enough it also impacts the variable wiper function that enables the wipers to adjust with the speed of the car.

This is solved by installing the original 40 tooth reluctor wheel from the 4L60e onto the T56 output shaft.

The second issue is the Traction control (and ABS) issue

This one took me ages to figure it out, but the manual transmission flag that you tick to disable the transmission related DTC’s also disables your ability to switch the traction control on and off. Un-tick the MT flag and traction control will work again, however; you will now have a multitude of DTC’s to deal with.

Hardware

Custom 40 tooth relcutor wheel

Someone has already solved this issue and written a very in-depth post about it, I will just give the basics here.

T56 VSS and Reluctor wheel setup on 1981 Corvette
Page 95 and Page 101 is where the information is.

T56 4l60e/T56 Reluctor wheel

You’ll want to grab a 4l60e reluctor wheel and the one out of your T56. To get the one off your T56 you’ll need to pop the rear housing off and it should just slide off the splines (it is the splined variant). For the love of all things good, do this before you install it in the car, it is a paaaaaaain to do it in the vehicle.

Take both to a machine shop and have the machinist bore out the inside of the 4l60e reluctor and shave the teeth off the T56 reluctor. Press them together with lock tight in between. A big interference fit may crack the 4l60e reluctor due to the pressure as thin metal so try not to go crazy with that.

I’ve just pulled the photos from those forums I linked to.

(Before)

Reluctor Wheels Before

C360_2012-03-14-18-04-22.jpg (200.36 KiB) Viewed 9184 times

(After)

Reluctor Wheel After

2012-04-24_09-04-32_103.jpg (166.16 KiB) Viewed 9184 times

Wiring

VSS

Now that you have the 40 tooth reluctor installed, you will need to install a 4L60e Sensor and a spacer. I used a sump plug washer (m22 I think but don’t quote me) squashed in a vice to get the right thickness (about 1.5mm). You will also need to swap the mounting bracket from the t56 sensor onto the 4l60e sensor.

The reason for this is that in my case T56 sensor didn’t pickup the 40 tooth reluctor at all. I had to swap to the 4l60e Sensor to get any reading. Another point, due to the type of sensor being used here, they are VERY sensitive to the clearance between the reluctor and the sensor face. I used a 2-2.5mm thick spacer to begin with and I could only get up to 90 Km/h before the speedometer became erratic. I believe there was too much interference and the signal became to messy for the PCM to make out a clear sine wave. Dropping the spacer thickness down solved this issure.

Don’t forget to space the bolt attaching the bracket to the gearbox as well.

There is more in-depth information in those 2 forums linked above, they cover everything. Photos pulled from the same source.

(4l60e Sensor)

4l60e Sensor

(T56 Sensor)

T56 Sensor

4L60E Simulator

Now, because we no longer have the DTC’s being masked by the manual transmission flags in the tune, our PCM is going to throw a multitude of DTC’s due to it not getting all the correct readings from the gearbox inputs and outputs.

To remedy this we will need to create a simulator of sorts to emulate the values that the PCM wants to see in normal operation. To do this we need to know what it is expecting to see, listed below:

Wiring Diagram For Reference

(Image taken from Sheet 24 of 140)

L67 4L60E Wiring Diagram

Ohm Ratings

Temperature Sensor

When picking a resistor for the temperature sensor it needs to indicate a value above a certain temperature otherwise the PCM will think the transmission is not hot enough and you won’t be able to engage the TCC (if you want to play with that at all, see tuning section), a a 270 ohm resistor will equate to 79.25 degrees C.

Temperature Sensor Specifications

EdSVeKF.png (54.67 KiB) Viewed 9178 times

Pressure Control Solenoid

The pressure control solenoid works a bit differently to the other solenoids. The PCM looks for amperage not voltage for control. Min amps being 0.1 and Max being 1.1.

Force Motor Table Header

yx9wakb.png (15.38 KiB) Viewed 9174 times

Force Motor Specifications

gWmSjUS.png (24.63 KiB) Viewed 9174 times

Solenoids

Solenoid Specifications

Pressure Switch Configuration Table

Depending on what gear you want the car to think that it is in you can use this table to achieve this. Just ground the relevant wire to sensor ground. You could also use this if you could get the T56 to output which gear it’s in, maybe for switching between reverse, drive and neutral or something.

Pressure Switch Configuration

2Vd08b5.png (67.94 KiB) Viewed 9174 times

PNP Range Switch Configuration Table

I actually didn’t create a reference table for the range switch. If anyone has this information I will add it. I don't believe this is particularly important however, just relaying information to the dash about which gear is selected.

*IMAGE PLACEHOLDER*

PNP Switch A
PNP Switch B
PNP Switch C
PNP Switch P

Resistors

Given all this information, I went out and purchase a bunch of resistors to emulate what was expected by the pcm. I purchased everything from jaycar, you want wire wound resistors for the increase wattage, list below:

270 ohm 1 watt resistor x 1→ Temperature Sensor
33 ohm 5 watt resistor x 1→ Shift Solenoid A
33 ohm 5 watt resistor x 1→ Shift Solenoid B
22 ohm 10 watt resistor x 2 → TCC PWM Solenoid (Parrallel)
27 ohm 10 watt resistor x 2 →3-2 Solenoid (Parallel)
27 ohm 10 watt resistor x 1 → TCC Solenoid
5.6 ohm 10 watt resistor x 1 → Force Motor / Pressure Control

If we wire up a small box with these resistors in place of the 4L60e we will alleviate all the transmission related DTCs and the engine will run happily. However;

Reverse Lockout Solenoid

Now that we have an understanding of how the PCM controls the 4L60E, we can leverage this to our advantage and use it to control the Reverse Lockout Solenoid with just a relay. There are a few ways you could do this, I initially wanted to use the TCC enable output (hence the reason I know it wont enable below a certain temp), however; the TCC is hard coded to disable at 0% throttle position. I ended up shifting focus to the 2-3 Shift Solenoid (B) and tuned the PCM to “Shift” from 2-3rd at 10 km/h.

You will want to wire in a relay in place of the resistor used to replicate Shift Solenoid B and configure the pressure switches into a state that it will enable energising the solenoid. You can either configure the pressure switch to limit to the car to 3rd (D3) or configure it to drive (D4) and set shift the 4th point to the max value (209.15)

Note
I found that the ohm rating of the relay (about 80-90 ohms) didn’t actual phase the PCM at all, no codes were thrown. This lays a case that you could increase the ohm ratting of all the resistors used in the emulator, this would in turn reduce the supply wattage needed from the PCM thus increasing longevity and reducing heat (15 watts is a lot of heat).

Finalised Wiring Diagram

Drawn Diagram

Tune

Now regarding the cruise control issue, this will require a calibration of the VSS parameters in the PCM (outlined in solution 1) and Dash to account for any tyre changes or diff changes you did while undertaking the gearbox swap. If you’ve just done a direct gearbox swap and changed nothing else, you wont have to touch anything. Your speedometer will be the same as before and cruise will work as intended.

Regarding the traction control issue, this is exactly the same as solution 1, except we’re adding a couple of modifications to limit or completely remove the amount of current passing through the resistors we’ve installed. We will also calibrate shift solenoid b for the reverse lockout if you wanted to go down that route. The resistors will get very hot and in some cases and throw codes due to heat changing the resistance of the resistors.

Also, to give some perspective, we are looking at a maximum of 52 Watts of power, that is in the threshold of a standard soldering iron, you will loose your fingerprints with that amount of heat (I found out the hard way). Granted that is worst case scenario, we will try to use higher rated resistors where possible and as stated put as much of the resistors into de-energised states.


Shift Solenoids A and B

What we are trying to achieve here is a resting/driving state of 3rd gear. In 3rd both solenoids are disengaged meaning no power is being passed through the resistors. Without the reverse solenoid setup you would set the 2nd to 3rd shift point to 0km/h. With the reverse solenoid setup, we are going to shift from 2nd to 3rd at about 10 km/h (whatever you want really). Allow for some overlap like shown, if you set the same values for upshift and downshift the relay will have a pass over period where it will rapidly close and open.

You will want to modify:
Normal Mode 1-2-3-4 Upshift line - KPH V's TPS
Normal Mode 4-3-2-1 Downshift line - KPH V's TPS

Shift Tables

TCC

Set the TCC to enable at the Max value as the resistors will be energised when it is enabled. This will achieve a state of de-energised normal operation.

Set the TCC PWM duty cycle to 0, again this will achieve a state of de-energised normal operation.

You will want to modify:
TCC - Normal Mode - 3 & 4 Apply Rate Duty Cycle % / Sec Vs TPS
TCC - Normal Mode - 3 & 4 Apply % Duty Cycle Vs TPS
TCC - Normal Mode - 3-4 Apply KPH Threshold V's TPS
TCC - Normal Mode - 3-4 Release KPH Threshold V's TPS

TCC

TCC Bin Modifications

TCC PWM

TCC PWM Bin Modifications

Force Motor

The Force Motor is a little weird, when it is at 100% duty cycle it has no current passing through it. If you have a google, it will explain it more in depth, but essentially by design it needs to apply maximum line pressure should there be a fault (this also happens in limp mode). This means that when the solenoid has no power running through it, it will be fully closed, thus maximum duty cycle / maximum line pressure.

I also found that it threw a DTC if left with the factory tune, I think it was cooking the resistor and changing it’s parameters.

You will want to modify:
A/T - Force motor pressure(PSI) Vs TPS(%) vs Speed (kph) 0-103kph
A/T - Force motor pressure(PSI) Vs TPS(%) vs Speed (kph) 103-206kph

Force Motor Bin Modifications

3-2 solenoid

Finally the last solenoid, funnily enough it has the most current passing through it, creating the most heat and I actually don’t know how to disengage this :’). If anyone has advice on this I’m open to suggestions….


Closing Notes

So yeah that’s that.

Knowing what I know now, it would be very easy to do all this wiring again. All you need is a few resistors and a relay. Chop the 4l60e plugs off, wire in the resistors and grounds in there places, no need for aftermarket control boxes or loose wires in the loom. It looks almost factory.

Potential improvements could include “trial and error-ing” the resistor values to find out the absolute maximum resistance you could use before the PCM has a sad about it and throws a DTC. This would probably alleviate even more heat. You could probably implement more relays and start switching other things in the car or make use of the PWM functions of the Force Motor and TCC PWM solenoids. The PWR switch could also be maybe be re-implemented if you wanted to mess around with 2 separate tunes or something. I can’t be bothered with it however.

I’m personally running this setup at the moment. It works amazing and I feel much better driving around with ABS and knowing if I get a canary I won’t have to stress about passing the pit inspection. The cruise control is so much better now as well. It ticks all the boxes and solves all the problems I had. Photo below, excuse all the joins, I went through a lot of R and D to figure this out haha.

As always, point out any mistakes I have made and I will rectify them. Hope this helps some people, thanks again to everyone on this site for helping me with all my issues.

Internals, note the burnt relay wire from resting on the 3-2 solenoid.

Emulator Internals

Loom before being tucked away, note the temperature resistor wired into the loom.

Finished Loom

[Gareth]

What a fantastic write up!!

Thankyou for sharing

[vlad01]

I might add my 2c with getting bits for conversions and what not. You'll generally never get anywhere with Malwood unless you are ordering a listed and in stock part directly off their online shop. I'm still "waiting" on responses on a few items going back 18+ months and despite several follow ups, it went nowhere, even on the phone.

Dellow is the way to go, their parts are of high quality, however I found their consistency with sending the right stuff to be hit and miss often, bits missing or wrong items entirely. However, they are top people and will always sort out any issues you may come across, I guess it just must be who ever is sending out orders makes a mistake often

[antus]

There is some effort in that. Thanks for putting it together and shareing. It looks like there is 1 image broken in the middle, just above "PNP Switch A". Do you mind if I replace the images with on-site copies in your post to make sure it doesnt go away if imgur goes down one day? I've added a link to this in the FAQ page with the other guides to make it easier to find. Thanks again.

[Mr Tippins]

Hey Antus,

Yeah that's would be excellent, I initially wanted to do it that way, but obviously uploading photos is monitored a little bit in the interest of preserving server space. In saying this, the guide is kind of a final draft, so maybe hold off on the photos for now.

I need to draw up some proper wiring diagrams and upload them, they're pretty much done I just need to find the time to scan and upload them.

I *think* the pressure switch table is wrong and I want to pull my loom apart and double check it.

Finally , the broken image is because I didn't get around to mapping the range switch so it was a IMG placeholder for when I or someone else did.

I'm assuming the range switch dictates what the dash displays, so I don't think I'll be able to map it with just tuner pro... I don't particularly want to buy (yet another) license to envyous customs body diagnostics tool so I'm not sure what I'm going to do there. I'll have a look around in tuner pro and see if I can map it.

Maybe google....

Either way I can personally message you when I'm happy with the photos?

[Rhysk94]

Man thats a lot of hassle.
When I T56 converted mine I had none of the issues you had.
Cruise worked as per normal, abs worked, no dash lights.
All I had to do was change the cluster ppk as it read half the speed.

Bloody killah write up tho

[antus]

All the images are now hosted locally

[vlad01]

Silly question, but couldn't you have just turned off all the auto associated codes and functions instead of all those resistors and relays?

That's all I had to do in 11P to run a manual so I'd imagine the later VS-VY PCMs would be much the same.

[Mr Tippins]

So I checked the Pressure Switch table, just to be sure. It is correct, to elevate any confusion, "0" means ground "12" means open connection.

Regarding just turning of the DTC's

I believe that's what ticking the MT flag will do, but as stated your traction control won't work anymore. I don't know of any other way to disable DTCs. However I am by no means an expert in tuner pro so there very well may be a way to do it. I couldn't find a mention of it anywhere and I did make a post about it initially a few years back. Definitely throw up a how to link up or something if you, I would be interested.

All the images are now hosted locally

Thanks Antus