Think you can diagnose this 48re ???

[QMFB]

The thing is crazy....

Just finished a rebuild on the 48re in my 04 dually. Put quite a few goodies in there.
Ok, so I pull an all nighter at my buddies shop, get the trans back in the truck at Dawn, and take her out for a test drive. Thing ran better than it ever has. I'm happy with it, drive back to the shop and load my tools, then make my way home about 40 minutes away and get some sleep. Truck ran awesome the whole way...
Next day, I decide to go out and make sure everything is dialed in and get some pressure #'s. Well, to my surprise the line pressure was 90psi at idle (right about where I wanted it), but did not rise while driving. So I get back to the house and see the TV cable isn't connected to the lever? Ok... So I hook it up and take another test drive. And now it doesn't shift past second gear, and line pressure range between 0 - 4,000rpm only goes from
90 - 120psi? And Governor pressure never excedes 15psi?
So I double checked with another set of mechanical guages, and it was confirmed.
I checked voltage, continuity, resistance on everything in the system. VSS, TPS, Solinoid, Transducer, Harness, relay, ECM signal in and out, current... All good. But trans still doesn't shift past 2nd?
So I change out the solinoid and transducer anyway (GM 4L60E, and a 3rd design conversion transducer), still no change.
Towed it back to the shop (75mph down the highway in 2nd gear didn't sound good) put her on the lift and drop the pan... Everything looks perfect. No blown servos, snap ring pieces, sparklies... Nothing.
So I run an air test on Pistons, bands/servo's, and the all actuate nicely, I pull the valvebody and do a complete tear down and cleaning. Everything looked pretty good. 1-2SV, 2-3SV, regulator, and shuttle "maybe" mighta kinda had slight roughness to them, so they got polished off with Croacus Cloth...
Put her back together and drive... Still no shift past second gear. Mechanical pressure readings remain the same, and so does the scanner...

Thoughts, Ideas, words of wisdom, or a flat out miracle would be welcome!

Thanks all !!!
I

 

[Gwoody]

Unplug the 8 pin connector and see what governor pressure does. If it's not a VB issue it should max out causing you to get a 3rd gear start.

 

[QMFB]

Now things are getting strange. Ended up swapping out VB's for my buddies Revmax VB. Fired it up and ran a actuation test while sitting in the shop. Now it has good Gov pressure, although line spikes 200+psi when first put into gear. But I'll have to deal with that later...
So after actuation test I shut er down, clean up a bit, and give everything a once over. Go to fire it back up for a test drive and the BTSI is engaged. Well, ok. I get that straight, and then when I fire it up, all the lights start flashing and the horn is honking, just going crazy. And just about every p code possible is set. While sitting through that mess, I've got it idling, and I hear a squealing. So I run around to the front and the Alternator is just absolutely burning up. I mean so dang hot I can't touch it.
So I go get a new alternator, install it, and fire it back up. And now none of the gauges in the dash work. At least everything in the PCI Bus isn't working. Manually check Voltage and it's good, but the new alt is getting hot. So I shut it down and spend what seemed like forever chasing wires, cleaning loom connections, and adding a few new grounds here and there, and try again.
Now it cranks but won't fire. And I'm about to the end of my ability ! Electrical diagnostics and I tend to not get along very well...
I cannot communicate with the ECM any longer, but I can communicate with some other modules, and these are the last of the codes I was able to pull..
Ideas? ECM mess the bed?

 

[spooled05]

Have you washed the engine bay recently? I had a ps line leak so after finishing up I washed it all down good and got a little water in the fuse box and it made all kind of electric problems. The alternator was going at full charge and all kind of weird $hit . I ended up pulling the box and blowing it out and got about a 1” puddle of water .

 

[kole32]

Check the fuse box ! My buddy had an 05 that did all kinds of wild stuff like this randomly. The fuse box was very corroded have to unbolt it and pull it out to see it all.


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[ComnRailPwr]

I'm also betting it's tipm. Unplug abs module and see if you can communicate with ECM.

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[QMFB]

No corrosion on/in the TIPM, but disconnected and cleaned it anyway. Found a glitch in the PCI signal and traced it back to the harness trunk connector. Cleaned and reconnect. Also cleaned and inspected every dang connection between the driver seat and the front bumper...
Truck starts now and the gauges work except Voltage, still nothing there but alt is pushing 14.75(+-)...

Biggest problem now is that I am no longer getting Governor pressure control from the ECM. The 5v supply for the transducer is there, along with the return signal. But pin#1 which is the 12v supply for the Gov solinoid dead.
I chased it all the was back to the relay, and then to the ECM transmission relay control pin. The circuit is good, but the ECM is not commanding the activation of the relay. I bridged the relay at the TIPM and got 12v at the 8pin transmission plug, but the ECM also will not send (receive?) The ground signal through pin#5...
So I'm stuck driving in either 1st gear or reverse for the moment. No Bueno Toro Caca...
I'm leaning towards fried ECM at the moment, but still hoping I'm just overlooking something?

 

[QMFB]

Also, I did check PCI communication with a short to power+, and by a short to ground-. Both checked good. But I do pick up residual (leakage?) Voltage on pin#1 (gov Sol supply) at the trans connection. Less than a volt, but readable none the less.

 

[spooled05]

When hp tuners was first available for our trucks one morning I went to go to work and couldn’t get out of first gear , checked everything under the sun , come to find out the ecm had no power to the trans relay . I reflashed the tune back in and all was good , only time it’s ever done that .

 

[QMFB]

I forgot to mention that when I access the ECM through my tablet, I can command the ECM to activate the Transmission Control Relay, and it will. It just won't do it in its own.

 

[QMFB]

Didn't even think about that. Thanks Spooled05 !
I did flash in a more conservative tune that didn't have any transmission tables changed from stock, before I put the new trans in...
Maybe some bad connection already existing in the harness, that caused the Alt to fry, also corrupted the tune flash?

 

[spooled05]

Idk but these electrical systems can do some funky stuff and make you crazy that’s for sure ! Good luck on getting it figured out .

 

[QMFB]

Finally got a ride lined up to get back to my buddies shop. Looks like it's gonna be another all nighter... Hopefully I'll manage to drive it out of there before dawn with a bit of luck.

 

[QMFB]

Looks like we have a trio of winners!!! Y'all nailed it.
After spending most of the night running through electrical flow charts, I've narrowed it down to the PDC. While testing circuit T515, I put a jumper into the relay socket to get a total ohms reading, and my headlights came on???? Ok, yeah that's not right!!
Further investigation shows constant B+ on the surrounding relays. Most of which are suppose to be key on+.
I can't believe the truck wasn't showing more symptoms than it was.... Nuts.
Now to see if my buddy has a PDC floating around out back. Lol.

 

[QMFB]

Oh, and I'm gonna be pulling the trans this morning too. Well, at least the OD section... Looks like I may have damaged the OD gasket on assembly. Had a few gallons of ATF on the floor when I came in yesterday... FML.

 

[thatguy69]

Atleast your making headway. Even if it is painstaking lol

 

[spooled05]

You ever get it figured out Q ?

 

[QMFB]

Yeah, sorry for slacking... Replaced the PDC. It fixed the current leakage issue, but not the main problem. Swapped out the ECM, and the problem remained the same... Chased the No Voltage on the dash guage issue, and found a heavy IOD issue. Chased that to a heavy drain on the 4x4 module circuit. (Which I don't have, mine is manual shift) so I completely disconnected that circuit. Didn't help the voltage guage, or the trans problem.
Opened up the old (10 years ago,) splice bundle for the CoPilot at the C2 pigtail at the ECM and found a crazy, rats nest of unprotected yet soldered connections. Downloaded the install instructions for the CoPilot and found SEVERAL splices that were not called for. Had 5 different lines spliced into the same ECM ground for some dang reason. Didn't even trace em. Just clipped em out, and soldered em back in stock.
Problem solved.
What I don't get, is why it was an issue just now? I don't believe in coincidence... But it appears as if that was the case.

 

[QMFB]

Still haven't replaced the output seal. Even though I have extras. I'm a little lazy.. lol