She won't fire up. Please help me! I"m at a complete loss!

[jorgensensc]

Thanks for the replies guys! I posted the info about the tranny plug in hopes that it would help others. I honestly just came upon it by chance. I couldn't figure out how the plug was Turning in the socket and engaging. Just didn't make sense. But the tranny was driving the truck, so I thought it was connected. And I wouldn't have figured it out until I got the new computer. Then it may have still been blamed on the mismatch of engine and tranny.
I've triple checked the wiring and tranny fluid. They are correct. On the scan tool I get two codes. One saying communication error, and one asking for the mil light to come on. That tells me the ECM and tranny aren't communicating. I'm hoping when the 2011 ECM arrives it will then communicate with the tranny. Fingers crossed!

I do find it interesting that if the tranny isn't connected, I can drive around in 3rd gear. When the tranny is connected correctly, I can't get out of first. The ECM is supposed to tell the tranny when to shift out of first. So that is probably the reason it's staying in first. Also the 2008 6l80e tranny uses a brake switch wire to release the TCC. This gets wired to the ECM and also from the brake switch through the tranny plug into the TCM directly. On the 2011 tranny the wire still goes to the ECM, but that's it. There isn't a seperate wire that goes to the tranny. The ECM tells the Tcm when the brakes are applied and when to release the TCC. Small interesting changes.
On the 2008 tranny most of the internal switches are normally open, on the 2011 tranny most of the internal switches are two position normally closed switches. Small changes cause big headaches!! Thanks GM!
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[Hart_Rod]

Any updates? Still waiting on pictures...... Also, the Corvette pedal plug has 6 wires:

purple
light blue
light brown
dark brown
dark blue
white and black

[jorgensensc]

Sorry. No updates yet. Waiting on the computer. Thank you for the pin out. Sorry about the pics. I have been swamped. I'm in the middle of this engine swap. I'm adding a bathroom and a laundry room to my house also. Also have to get the AC system completely replaced in the house. And i have to get the suburban done. All before the beginning of August. That's when baby number 4 is due. Somewhere between August 8-15 (although I told the Dr. I think he will come August 2nd). That is why I have been so flakey on my photo commitments. I will get them tomorrow though.
Shawn
Shawn
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[jorgensensc]

As promised, a few pics. I'm almost embarrassed to post these since I haven't had a chance to clean anything up yet. Hopefully they will help a few folks out. I put the engine in without modifying the driveshaft at all. It put the engine pretty far forward. If I had it to do over I would probably cut down the driveshaft and move the engine back a couple of inches. Still may do it after I make sure everything is up and running correctly.

[jorgensensc]

Don't know why they are all sideways. they weren't that way when I uploaded them.

[orngsikL]

check trans fuses again

[jorgensensc]

Thanks for the advice. I checked the fuses one more time. They are all good. As an experiment I pulled the fuse for the tranny, then I drove it around the block. Only ha third gear. Then I put the fuses back in. I only had first gear. This seems to validate the two things I have been told about these trannies.
1) When the tranny has no power, it goes in limp mode, third gear only.
2) The 2008 Ecm is not communicating correctly with the 2011 TCM (different operating systems) So the tranny is functioning correctly, but the ECM isn't telling it when to shift, therefore it stays in first gear.
We will see when the new 2011 ECM gets here.

[68GMCCustom]

GM makes wiring/pinout changes regularly....I sure hope you don't run into an issue changing ECM's.

[jorgensensc]

We looked at the pinouts (or rather Jon at PSI did). He said they appear to be the exact same pinouts. I was concerned about that also.
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[Custom 68]

I am sure the shifting is speed dependent, that said make sure you have the speed output from the tranny also hooked up. If you can drive it with a scanner running check to see if you have speed output into the computer and that is correct or atleast close to what you are running. I know that can really mess with them

[jorgensensc]

Thanks for that. There isn't an external speed output on the 6l80e. The scanner does show correct speed when hooked up.
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[Custom 68]

Great (I guess). I thought my gen 3 stuff was pretty hi tech but this looks like it is even better lol.
I had held back on much input only because mine is like I said the Gen 3 so I knew they had some big differences but also some similarities. We are rooting for you so we are anxious to see it run and run right.

[jorgensensc]

Thank you for offering suggestions. I hope I'm not coming across as a naysayer. I need all of the support I can get. I really appreciate your input and taking time to post your ideas. I guess I just need to wait for the new ECM (if it will ever get here). We will go from there.
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[BR3W CITY]

^Amazon Prime....I don't wait more than a day for anything.....

Does your scanner allow shift commands? I know some of the fancy ones can command individual gears, though usually its easier just to do in HP Tuners. I know you've had 1st, and 3rd, but I'd really be interested to see if you can command all the gears. This may not even be an option without the 2011 ecm as I'd assume the scanner would have to hook to the OBDII port then through the ecm to command the TCM...but I was sitting here and figured it would be worth tossing out.

[jorgensensc]

Ha! I usually don't wait more than 2-3 days. However, the yard I got the engine from doesn't have a 2011 ECM. Jon over at PSI is getting me one for no cost because of a mix up with the wiring harness. So I just got word from him that his supplier said it will be to him by Friday then he will be sending it my way.
Unfortunately my scanner is not quite that capable. I wish it were.
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[Custom 68]

We are back for updates? Any good word?

[jorgensensc]

Just got notified the computer is shipped today. As soon as I get it installed I will let everyone know where we stand! Keep your fingers crossed!!
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[Custom 68]

cool, I hope it works great... fingers are crossed.

[oldman3]

Standing by...Jim

[jorgensensc]

UPDATE:
Got the new computer today and she now shifts through all gears. I was all excited that I took her for a little spin down the freeway. She ran pretty good, then something odd happened. She had no throttle response at all. I coasted her off the freeway and came to a stop. There was no response from the pedal at all. She just idled.I could hear it go in gear, but wouldn't move. So I turned it off. turned it back on and it idled like crap. But would idle forward (instead of idling and not moving at all), but ran like total crap.So I idled it another half mile towards the house when I decided to stop again. I then pulled the fuses for the tranny, started her up, and had third gear (like before I got the new computer). It drove just fun. So I stopped and put the fuses back in and it drove fine again. I drove it for awhile (didn't hammer it like I did when I first drove it on the freeway) and it drove and shifted fine. Then I drove it to pick up one son from daycare and it drove fine. It shifts a little odd, but that may be in the tune. Again I didn't hammer it the second time.

So pulled a couple of codes from it that I'm a little confused about. I cleared them and they reappeared. I got codes p0641 and p0651 and P2122 and p2123. The first two are low 5v reference, I think for some ac and fuel pump reference voltage. It may need to be programmed out of the ecm still, so I'm not terribly worried about those. The other two p2122 an p2123 are the ones I'm confused about. They are low and high voltage on the APP sensor. I didn't have this code on the other ECM that I was running before. Literally I unplugged the other ECM (with no code except ac refrigerant sensor) and plugged the new one in. So I have a few questions:

The new ECM is from a 2011 silverado with a 4.8 engine, is the pin out any different than the pin out for a 5.3 or 6.2 ECM? My alldata is for a 2011 5.3 ECM and the APP pinout is identical. I just don't know why it would throw those APP codes unless the pinout is different for the 4.8 vs the 5.3.

Is there any difference in stock torque convertors on the 6l80e in the 4.8, 5.3 or 6.2? I can't seem to find this info anywhere, and I'm curious if this is the reason for the delay after pushing the gas pedal and when the truck accelerates. It feels a little exaggerated. This may just be in the tune also.

The computer is tuned for a 4.8. Is there a tremendous difference in what the power and drivability should be when I get it tuned for the 6.2? May seem like a dumb question, and I'm sure it will. Actually I'm rally hoping so. I'm not terrifically impressed power wise, but it may just be the tune and tranny controls that need adjusting.
Thanks for the help guys!!
Shawn

[Russell]

Get the right tune in it. That'll make a huge difference in power. You've got nearly 2L extra displacement that isn't being fueled for and potentially totally different timing curves which are likely having a considerable effect on your engine's efficiency.

Have you actually measured the voltages being supplied to and returned by the APP? The PCM may be onto something you don't know about yet... Perhaps the pedal is travelling too far and is causing an over-range condition and putting your PCM into limp mode? You may want to consider purchasing EFI live or HP tuners to work on some of this stuff yourself. You can load your own operating systems, tunes etc into your own vehicle and also have a very powerful scan tool at your disposal then too.

Gotta love this stuff hey? Mixing and matching can be a real challenge. This is one of the reasons why I always buy a complete running donor when doing this kind of a swap. You never know if it is a pre-existing issue with the engine due to a sensory failure, mechanical problem or if it is your wiring / install that is to blame. If it worked before, it should work when installed properly, lol!

[Custom 68]

Yes tune it, I would not hammer on it till you do. The amount of fuel required for the 6.2 will be much different that that for the 4.8. Plus I would expect the injectors are different so that calibration will need to be accounted for. I would be very cautious until you get a better base tune.
OK, I have hp tuners so I grabbed a stock 4.8 and 6.2 from the repository. It appears they both have the same tranny I think. However there are different settings on the tranny depending on which one either the 6.2 or 4.8. Plus there are some huge differences in the injectors so yes It might run but not right with the smaller tune.
If you can get a stock 6.2 tune flashed on there it might clear up most of these problems. Be careful till you do.

[jorgensensc]

Great! Thank you guys so much. It sets my mind at ease a little. I will hopefully get it tuned tomorrow. Thanks again guys!!
Shawn
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[BR3W CITY]

Those app sensor codes have happened to me before. Bascially they happen to the DBW stuff when the input power drops too low. This happens when the idle drops or you have an instant load which decreases available system power to the ecm and DBW.

I've had this happen with my hydroboost installation. I was slowing down, big load came on the engine from the hydroboost (same thing would happen with a/c, high amp alt, EDC etc). The rpm dropped, engine couldn't catch idle fast enough with the big cam and it stalled then caught right back up.

Output voltage stops from the alt, and the engine gets a temporary low power output fault. I did a battery reset, pinged the ecm and cleared codes/flags, and re-started, letting it settle into idle for about 3 minutes. Code never came back.

[jorgensensc]

UPDATE! She is running and driving almost perfect!!! Got the tune done and she is a beast. I am extremely impressed!! The tuner did what he does, turned down torque management (he doesn't like to turn it completely off). We drove it around a little after the tune and all I can say is WOW! Money well spent. It will spin the tires a little from a stop but gain traction quickly. Then chirps the tires hard when 2nd gear hits. Blew the doors off a newer Escalade at a stop light.
Still trying to work a couple of things out you guys may be a le to help with. I get a p0108 code(high map sensor voltage) the minute I turn the ignition on. I. He med voltage and it appears to be correct. I changed the map sensor anyway and still get the error. I get 5v at ignition on. Ground wire is good. And 1.1 volts at idle from PCM wire. The voltage goes up accordingly as the throttle increases.
Also the engine keeps going into limp mode at WOT or even steady 3/4 throttle. Only code is p0108. I read somewhere that if the map sensor reads above 4.7 volts for more than 4 seconds it can do this. Any ideas? Thanks again guys! I'm super stoked to have it running, even in its hampered state.
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