4L60E in limp-home mode...can't figure out why

[silver69camaro]

I have a 4L60E trans out of a 2002 Silverado hooked up to a 5.3L in a 1964 Corvette. The wiring harness is from PSI and the ECU was tuned by Texas Speed.

For some reason, the trans is in limp home mode. I verified power to pin E at the connector with the key on. Obviously fuse is good. The only codes that I pull up are a P0443 and a MIL malfunction code (MIL lamp isn't hooked up yet), but I can't imagine these codes would cause that problem.

The only thing I can possibly thing of is I drove the car around with the MAF disconnected...I know the ECU uses info from the MAF to determine line pressures and such, but I know people have disconnected their MAF without trans issues.

I'm assuming it's in limp-home mode because putting the gear selector in OD results in 2nd or 3rd gear. I can get a lower gear by putting the selector in 2nd or 1st. Reverse works OK.

So I guess my question is, what else can cause the trans to do this? What else should I be looking at?

[parsonsj]

Matt,

Are you sure you have a valid VSS signal to the trans? I've battled that problem before...

[silver69camaro]

I think so. The speedo reads the VSS fine so I would imagine it is.

[parsonsj]

Is this a stock PCM? I *think* (not sure) that raw VSS (40 pulses per output shaft revolution) goes to the PCM, and then separate conditioned VSS (16000 pulses per mile) lines are sent to the transmission and to the speedo. It's worth a check. Can you attach a "dashboard" to the trans? See the inputs as it does?

[silver69camaro]

It is the stock PCM. I might be wrong, but I think the VSS sends a signal to the PCM, and the PCM sends outputs to the shift solenoids. I don't know really, I'm more of a manual guy. This is my first time with a modern auto, and it's driving me nuts.

[silver69camaro]

Update, turns out the ECU was initially flashed from GM for a 4L80E, not a 4L60E. I'll get that straighened out and see what happens.

[parsonsj]

Cool! Let us know if that fixes it.