All,

I have an LS3 and 4L75E from BluePrint Engines. I have the main vehicle harness done as well as the ECM Harness. I'm about to start the MSD TCM (pn 2760 and harness pn 2771) wiring and have a few questions. Here is what MSD has in the instructions. My comments / questions are below each section after the "-"

BROWN (OVERDRIVE CANCEL): (FORD ONLY) Toggles Overdrive function on/off with momentary connection to 12v(+) or ground(-).
- I do not need this as far as I can tell

BLACK (TPS GROUND REFERENCE): Connect to ground reference on throttle position sensor (TPS).
- I have been told this is a black wire at the throttle body or the throttle pedal. There is also a ground reference in the LS3 bulkhead connector, but would prefer to get all the TPS wires from the same location

GRAY (CALIBRATION SELECT): Switch to ground to select Calibration B. In race applications Calibration B can be used for aggressive shift characteristics. In 4x4 applications Calibration B is used as a shift point compensation using the Transfer Ratio (INITIAL SETUP) setting to compensate for transfer case reduction ratio in AUTOMATIC shift mode. Connect to a switched ground to activate.
- I think I get this. I'll put this to a switch on the dash to switch from one calibration to another.

BLUE (MANUAL BUMP UP / MANUAL MODE SELECT): Momentarily switch to ground for 3 seconds to activate MANUAL MODE. Once in MANUAL MODE, momentarily switch to ground to UPSHIFT.
- I think I get this. This will connect to my Lokar shifter (ES4L60E) for manual mode

GREEN (TCC LOCK): Switch to ground to lock Torque Converter Clutch in 2nd-4th gear regardless of vehicle speed.
- Do I need this? I'm not using Nitrous or trans brake

TAN (SPEED OUT): Speedometer signal output (12v square wave; 20,000 pulses per mile).
- Don't think I need this. I am using a GPS speedo

RED (TCC UNLOCK): Switch to 12v to unlock Torque Converter Clutch. Normally connected to brake pedal switch to unlock TCC when brakes are applied. Note: This function will prevent the TCC from locking under any operating condition while activated with 12v.
- Not sure If I need this, but I can easily attach to the brake wire

ORANGE (TPS 5V): Connect to 5v reference on throttle position sensor (TPS).
- I've been told that this is only available as a red wire at the throttle body. I'd like to get it at the pedal if possible. Anyone know a good location?

LT. BLUE (MANUAL BUMP DOWN): Once in MANUAL MODE, momentarily switch to ground to DOWNSHIFT.
- Connect to shifter

PINK (12V IGNITION IN): Connect to switched ignition 12v source.
- Does anyone know if this needs to be true ignition, or just ignition?

WHITE (RPM/TACH IN): Connect to tach output on MSD Ignition or coil (-) on inductive ignition. Note: Will accept 5V(+) used to trigger GM LS coil packs.
- Connect to wire going to Tach

YELLOW (TPS SIGNAL IN): Connect to TPS sensor signal.
- I have been told this connects to a yellow wire at pedal or at throttle body. However, I didn't see yellow wire at the pedal. There is a purple wire at the LS3 bulkhead - Throttle Pos #2 (0.5v - 4.5v). Again, I'd prefer to get it from the same location as the other TPS wires

VSS - On the TCM harness, there is a plug for VSS. Since it's close to the main tranny plug on the harness, I assume this plug into the transmission. However, there's already one plugged in from the LS3 harness. Which one do I use? Or do I need both? Again, I'm using a GPS speedo

Thanks,
Jim

 

I don't know if this applies to a stock PCM or not, but I know you can't split the TPS signal on Holley EFI to run the MSD trans controller.

Holley told me it wouldn't work, I tried it anyway...they were right.

The Holley probably uses different circuitry in their ECU compared to a stock PCM, but I at least wanted to mention my experience.