Ok if I lock up the TC via the ALDL it locks. If I let the computer control the lockup function it will not. All the wiring checks out good. Also when having the laptop hooked up, the ECM shows that the TC is locked up but isn't at all.

Any ideas?

Car is a 88 Camaro Vert with a 90 dash tbi inteior harness with a 91 tpi engine harness.

Im using a Moates adapter with the SAUJP_4 bin.

Also which pin does the ECM use to ground (not F6) but to actually ground the TC solenoid?

Thanks!

 

ECM was bad.

 

Well I was wrong. The ECM wasn't bad at all.. Here is why.

The ECM I was using was from a Turbo Sunbird or a Sy/Ty. How the hell I ended up with that I dunno. The part number is 16198263 and it is a GM Reman. The new, well used ECM is a real 7730 ecm out of a 92 V6 bird.

Anyways when I did the TBI to TBI conversion orignally on the old setup, I just used the harness I had. The kicker is that the ECM receives the VSS signal from the VSS Buffer into the ECM (A10 to BC6). BC6 is a the buffered input for the 730 ECM.

When I got rid of the TBI engine harness in favor of the TPI harness, the VSS in fed directly into the ECM via pins B9 and B10..

What got me thinking about the buffered input vs direct input.. When I was comparing the two ECM's I noticed the on differance on the 8263 ECM. Where the TCC wire pins to (GF6) there wasn't a resistor solidered on the board. So thats what got me thinking.

Since both ECM's are essentally the same, they should work the same. Thats what I thought. I'm going to go out on a limb here and say since the 8263 ECM (and the applications that it is used for) use a VSS buffer box and the ECM redirects the signal for the TCC lockup differently than the 7730. Hence why the 7730 has a resistor on the TCC lockup pin.

Wow that took me 2 years to figure out. lol. Now time to get the resistance, soilder in a resistor and have a back up ECM.

 

The issue is that the Turbo Sunbird or a Sy/Ty ECM is not the same as the f-body '90-'92 TPI ECM.

More to the point, the turbo ECM is missing the quad driver that the TPI code uses to lock up the TCC. IOW, the '7749 is missing a quad driver that the '7730 ECM has installed.

Get a '7730 ECM and the TCC can be locked via the ECM when using $8D.

RBob.

 

Well that explains that even more so and yep already have a real 7730 ecm in use. Thanks RBob!

 

Wow..... quite the adventure there

needs more NVSRAM!

glad you got it sorted out dood

-jason

 

Be sure to flip the VSS bit to indicate Magnetic or Optical input.
If using the buffer box, use optical.
If the VSS reading was not getting read correctly the TCC output will not function.
There is also an option to run the TCC on RPM settings instead of Speed input.
The same tables are rescaled using RPM instead of MPH if that setting is used.

 

good info