Did GM ever make a drive by wire stand alone controller that will work without have a late model PCM attached?

 

GM did not make a stand alone controller for any electronic throttle body. I've been playing with this equipment for some time now, while building new engine conversion harnesses, and can tell you that they had good reason not to make a stand alone controller.

Liability. Electronic throttle is safe, but not on its own. The early electronic throttle systems (LS1/LS6 Corvette) work great but they're packaged as four components...

[PCM] - [TAC] - [Throttle Body] - [Accelerator Pedal]

TAC operations
- monitor TPS voltages (two 0-5v voltages)
- control the throttle motor
- receive driver-controlled cruise control signals
- Class 2 data communications with the PCM

PCM operations
- Class 2 data communications with the PCM
- monitor vehicle speed for cruise control operation
- monitor throttle position (so many reasons)
- monitor pedal position

Accelerator Pedal operations
- reports 2 or 3 (depending on year/application) voltage signals to the TAC

Throttle Body operations
- reports two different throttle position voltage signals
- motor to control throttle blade

Now the PCM has safeguards in place to shut down the entire system if a "dangerous" situation takes place. I've actually toasted a PCM by changing certain electronic throttle values (using EFILive) beyond what GM would have considered normal. I also recall a "Throttle Coorelation..." DTC that has set in the past while tuning beyond certain thresholds.

Having kicked off the production of the first electronic TPI/LT1 throttle bodies, you could assume that I would have high interest in a stand alone controller. However, I would be more than cautious of a stand alone controller's abilities to pack all of the features and safeguards as the GM implemented system.

Here is the new 58mm throttle body we're now offering. 52mm and Mono-Blade also avaialble. They all use LS1/LS6 Corvette equipment.



I understand the cost drawbacks of a new fuel management system (PCM, wiring harness, tuning, etc) for a project, but if it fits the project's budget the results are amazing.

We finished tuning the S10 yesterday. The LS1/LS6 Corvette PCM, TAC, Accelerator Pedal, and new electronic TPI/LT1 throttle body make for an awesome package on this engine. The truck has excellent street manners, a rather smooth idle (and it's an LT4 hot cam), and lots of power when you put the pedal to the floor. The adjustability of the 4L60E and integrated cruise control are a bonus!

 

E40 ECM
At first glance it would appear that GM was on the right track to eliminate the separate, and expensive, TAC module by moving its functionality into the E40 ECM (early LS2 engine computer). However, they moved the cruise control functions to the Body Control Module and the automatic transmission functions to the Transmission Control Module. Cruise control remains a BCM function in today's new cars.

So how do you like that? Your new LS7 engine swap gives you all the performance, but for highway driving you'll keep your foot on the accelerator pedal.

In my own opinion, the absolute best option for cost, performance, tuning, drivability, and maximum features (like cruise control) is the 2001-2002 LS1 PCM system.

 

So the PCM monitors the 3rd TPS signal and if it find an error in the commanded TP derived from the TAC vs its internal throttle angle will it shut the TAC down? Is this done via a discrete input to the TAC or via the data bus?

 

There are only two TPS signals, but three pedal position signals. The two different TPS signals differ in that one signal voltage is increasing while the other is decreasing. I haven't looked too closely at the three pedal signals, but they each differ (within 0-5v) as well.

I'm not so sure that it will ever completely shut down the TAC, but in the very least it will operate in a reduced power mode.