Mods, please move to Drivetrain Article section... dunno why it posted here<<
First off, THIS IS NOT "MY" MOD!!!!! -I had seen it posted elsewhere around 2-3 years ago but since then, the website no longer exists... I am posting it here so that everyone else can benefit from it in the 1G AT arena... I have several other DSMers contact me about this in other related threads so I figured that I'd make it a Tech Article. So here' goes...
This 1g AT mod give a sort of Tip-Tronic shift ability to the user. It also provides full line pressure to seriously firm up shifts even on a stock tranny. It is also helpful when on the dyno and with most stock TCU-controlled setups, the TCU wants to downshift under WOT conditions.
This mod is specific for the 1g(b) Turbo AT DSM with the 2 yellow plugged TCU and although the same premise also exists for other AT guys, the wiring would be totally different. Also note that my TCU is actually mounted upside down in my car.
This setup requires the following:
x2 Standard automotive relays
x1 3.3 ohm, 5%+/ tolerance, 10 watt resistor
x1 additional 1g TPS sensor
Fully functional AT TCU & trans
Voltmeter
A few lengths of different misc colored 16AWG wire (about 6-8 different colors)
~x15 female spade connectors (for relays)
Soldering iron & shrink tube (or butt connectors)
The 1g style TPS sensor needs a 5v+ input. Since the engine's MAF has a 5v+ feed from the ECU, you will need to splice into this wire, at the ECU location. It is pin #23 on the ECU as seen on the VFAQ, here:
http://www.vfaq.com/mods/ecu-harness-1G.html
Wire the TPS like this:
"+" -5v+ input spliced from the ECU
"o" -pin 87 on relay #1 (modified TPS output to the TCU)
" " (no marking) -no connection
"-" chassis ground
Wire the relays like this:
Relay #1 (interrupts the original TPS input and feeds secondary TPS value into TCU thus creating an imminent shift condition)
87 -Modified TPS output (0.5v+, explained later)
87a -TCU Pin #21 WHT/GRN wire (cut this wire and connect the wire harness side to this pin on the relay)
30 -TCU Pin #21 WHT/GRN wire (other half of the cut wire, TCU side)
86 -chassis ground
85 -12v+ trigger (any 12v+ source to activate the mod*)
Relay #2 (interrupts the flow control solenoid thus providing full line pressure shifts. This relay is required to keep the TCU from going into limp mode if this secondary relay is not configured as illustrated below)
87 - 3.3 Ohm resistor lead (connect the other side of the resistor to chassis ground)
87a -TCU Pin #14 Solid Blue wire (cut at the TCU harness, connect the wire harness side to this pin)
30 -TCU Pin #14 Solid Blue wire (cut at the TCU harness, connect the TCU side to this pin).
86 -chassis ground
85 12v+ trigger (same as in relay #1, any 12v+ source that will be used to activate the mod*)
First thing you have to do is adjust the TPS value on the additional TPS sensor... This requires the voltmeter. After everything is wired up, turn on the ignition (but no need to start it). Then temporarily unplug relay #1's 87 pin. This wire's value NEEDS to be set at 0.5v+ from the secondary TPS sensor. To do this, hook up one of the leads from the voltmeter to this wire and the other to chassis ground. Manually turn the TPS sensor until the voltage on the wire that was plugged into Relay #1's 87 pin is equal to 0.5V+. You will need to secure the TPS sensor in this position indefinitely and there are a number of ways of doing so... I drilled a small hole in the TPS housing and used a small screw that threads into the hole and applies pressure to the TPS cog (See pic). By adjusting the screw, I could precisely adjust the TPS's output voltage to the 0.5v+ output. Once that value is attained, BE SURE to secure the TPS cog in a way so that it will not be adjusted buy road vibrations (I filled the whole recess with hot melt glue after I adjusted the screw). Once adjusted, plug the wire back into pin 87 on Relay #1.
Lastly, you need to connect a 12v+ trigger that will engage the mod... If everything was wired correctly, the AT will shift normally UNTIL this mod is activated. In order to activate it, both relays need to be energized by some sort fo 12v+ source. It can be any number of things as long as it is a 12v+ source that shows 12v+ ONLY when you want to activate the mod.
* I chose to splice the relay triggers into the "ECO" side of the PWR / ECO switch. If you choose to do the same thing, then the "ECO" mode's wire (a GRN/WHT wire, at the switch) will show 12v+ when ever the ignition is on and the PWR / ECO switch is in "ECO" mode. Splice into that wire and connect it to both relay's pins 85.
Once it is all wired up and the TPS value is permanently set at 0.5v+, make a few test runs... I recommend starting off in the lowest gear you want to start off in, using the gear select. Engage the mod (activate the 12v+ triggers on both relays). As you climb in the RPMs, manually up-shift at your desired shift point until you run out of road. Enjoy full line pressure shifts! Understand that if you downshift then the tranny will downshift at full line pressure. At certain RPMs that can be quite violent...I'd only recommend using this mod while launching off of the line and/or road courses when you want to stay in your power band. Disengaging the mod puts you back into stock AT mode.
I understand that there are a lot of other ways to generate the 0.5v+ output that's needed for the false TCU signal, but I figured that every DSMer
should have a spare TPS sensor... I had two spares and one of them was intermittent around 70-85% so I figured that it would work great for this mod. -So far, so good!
PM me if you have any further questions... I set this up myself and I have enjoyed it for around 2-3 years now without any ill effects. This is my first tech article so mods take it easy if I missed anything.
Good Luck
