t56 swap and auto codes??

[Ezzz]

Hey guys, my 4.8/t56 swap into my 69 C10 is just about done.

A while back my car would struggle sometimes at low rpms and a few times even died on me. Only to start back up fine sometimes minutes, sometimes 2 hours later. Had a code for an o2 sensor so swapped that and it seemed fine... until it wasn't.

Now I have the same issue but my only codes are for an automatic transmission and one for a MIL. They've always been there but I ignored them since I have a t56.

Obviously the smart thing to do would be to tune them out, but with no other codes could they cause the engine to do what it's doing?

Codes are:
P0650 Malfunction indicator light control circuit
P0740 Torque converter clutch solenoid circuit
P0753 Shift solenoid A electrical
P0785 A/T 3-2 solenoid circuit malfunction (4l60-E, 4l65-E)

Any helps appreciated

[ls1nova71]

Don't think those would cause your problem. Sounds almost fuel related to me, have you checked your pressure when it's acting up?

[Ezzz]

I haven't. Guess that's step one. Thanks

[ls1nova71]

Also, do you have a VSS? Sometimes not having one will cause stalling problems when coming to a stop since the PCM doesn't know you are slowing down and can't compensate quick enough. Not sure if this is your problem, just throwing it out there.

[Ezzz]

I do have a vss. Haven't calibrated the electronic autometer speedo yet so not sure if I have a good one I guess. Also it's more when I'm getting up and going than slowing down, unless that's the same issue with the pcm not knowing my speed changing.

[BR3W CITY]

Is the PCM setup correctly for the resolution of the VSS on the T56? I'd have to open HPT and look at the options, but running the wrong pulse resolution for the VSS you have will provide the wrong speed@load conditions. This can make the computer do things like go into DFCO or high idle at inopportune times.

[Ezzz]

That I am not sure of. The guy that did my harness also did my flash. He had an order form where I listed my setup, but there was a tuning issue with my pcm that I had to send it back to him to fix, so it's possible he messed that up too. He's in Arkansas and I'm in CA so it's almost 2 weeks downtime to send it out there. Really need to find someone local.

Wouldn't something like that throw a code besides what I'm getting? That's what's confusing me and not giving me much to go off of.

If it is PCM related and it dies on me, is there a quick fix to get it running again to get where I'm going (hopefully to a tuner lol)? Disconnect the battery?

[BR3W CITY]

Depends what the actual issue is. Some codes can be set to "not report", which means they will show up if logged, but won't flash a CEL or take any action.

The battery disconnect will reset trims, CEL's and readiness monitors. Some faults will only cause problems after the PCM see's them a certain # of times, for the readiness monitor to clear it. (Aka the reason you have to drive 100miles or whatever it is, before getting an emissions test. )

I'd also try grounding the outside of the PCM case too. If there is a problem with your internal grounding, doing a hard ground will help clear it for diagnosis.

[TwinsSpeedShop]

I had a similar issue where it would die or once shut off it didn't want to crank back. Ended up being the fuel pressure regulator on the rail. Check that