I am running a 1999 5.3 and 4l60E from a Chevy 1500 Silverado. I have had the trans completely rebuilt with a new Torque Converter. I am running a 2003 ECM and drive by wire on the 1999 engine. I was able to put about 200 miles with no issues but ended up burning up 3rd and 4th. Trans builder ran codes and it looks like the trans is not seeing engine rpm or tcm but the engine runs perfectly. Trans builder says trans is not putting enough pressure on 3rd and 4th clutches to keep them alive. Am I not going to be able to run the 2003 computer with this 1999 transmission? Any suggestions?

 

The 2003 computer should work just fine. But i would watch line rise while driving and make sure its happening, But the model of the trans is not your issue.

 

Thanks for the reply. Do you know if there is any differences in the pins for the computer and trans from the different years. For example
I had an issue with trying to run a 1999 alternator. The 1999 alternator would not charge but charged perfectly with an 03 Alternator. Just finding odd differenced like that.

 

Not in the year models you mention 96 to 2008 would all be compatible units for you plug/ wiring and electrically.
93 94 95 A DIFFERENT Story and 2009 up another story .

 

The 1999 vehicle should use a P0411 PCM with red & blue connectors. The 2003 uses a P59 PCM and should have green & blue connectors. Although they are similar in design they are not completely interchangeable. I am surprised that you got the connectors installed. Did you replace the engine harness? Check line pressure and make sure you have line rise. Check to make sure your MAF load goes above 90%. It should do this under 1/4 to 1/2 throttle.
Here is a link to a site that has a ton of information on this. https://lt1swap.com/2000harness.htm
There are a lot of reasons that you could have 3-4clutch failure right out of the gate. Bad MAF sensor. Failure to check the input drum for leaks, AFL bore in VB bad, leaks in the 3-4 feed circuit are the most common reasons.
Hope this helps.

 

Yes, the harness was updated to a 2003 in order to use the 2003 computer. The trans is not seeing TPS or RPM but the engine is and runs perfectly. Can't figure out how to get the trans to see TPS and RPM considering the engine is.

 

Got ya!
Not exactly sure what you mean by the trans is not seeing TPS or RPM. As long as the PCM sees those values, the MAF should calculate load %. GM transmissions are load based for pressure rise. So look for load % to go to 90% or better. It wasn't until later 2006 or so that they had a separate transmission control or tune. This was not the case with a P59 PCM.

 

I am pulling the trans this weekend and my builder is going to go through it again. I have total confidence in the guy working on the trans. He had his computer on it last weekend and stated there was only a slight rise in pressures and that is why it is burning up the clutches. He did say if he finds anything mechanically wrong with his last rebuild he would let me know and of course take care of it but he is pretty sure its a control issue that is burning it up.

 

You said "trans not seeing tps or rpm?" If you mean you are not seeing TPS in the data to the PCM well then no I would not expect much if any pressure rise. It varies to year and PCM tune but pressure is a function of TPS. GEAR, SPEED, MAF and MAP and tables for each relationship. If you do not have RPM or TPS it is hard to me to imagine the car can even run right much less shift the trans and set line pressure as even shift points are a relationship of TPS/SPEED/RPM and load -(as determined by MAP and/or MAF) This will need to be corrected or you will repeatedly burn things up. Though you could use the TRANSGO 46MOD for line pressure . I see no way short of some elaborate tuning to use only MPH which would leave fixed shift points at all throttle to even get it to work at all.
I would say priority would be to get that TPS and RPM signals to PCM as a priority before even pulling trans as before or after it will have to be addressed.

 

The PCM is seeing TPS and RPM and that is what is causing the confusion as the engine runs perfectly. It does see some pressure rise but hardly any at all.

 

You will need to correct that in whatever way is needed. The PCM can compensate for the TPS missing signal for engine running. But not for trans line or shift timing . Probably need to get out the ohm or volt meter and check for reading at PCM and correct as needed . I would tackle that before I even pulled the trans personally. It is better to reinstall and know ready to go than to install and then troubleshoot IMO.

 

Some of the things you are talking about, I learned the hard way!
This specific malfunction is why I ask about the load % it can be viewed with HPtuners it you have that. Most decent scan tools will show it too.

I also agree with @FranksCustomTrans you should address that before you pull it out again.

I would ask if the builder resealed the input shaft to the drum? I do every one I build because 90% have a leak at the 3rd feed where the shaft presses into the drum itself. I would also ask if he blocks the 3-2 sequence & 3-2 control valves? He may say only a hack would do that!

Both of these mods have been tested tough by guy's like myself that performance build for a living. One of the guys on here that promoted these mod's work for GM Hydramatic division! Another guy is an engineer and works for a performance transmission shop.
I also block the 3-2 sequence & 3-2 control valve inboard. Both these modifications shorten the 3rd feed circuit. GM did away with the 3-2 control valve for 2009 & up because they realized it actually served no purpose. TransGo has been blocking the 3-2 sequence in their 4L60E HD2 kit as long as I have used them.

 

Everything Frank and Transman are saying is in complete agreement with every 4L60E expert, designer and performance builder who is and has been on this forum.

As explained, but perhaps a bit hidden in all the details, is that the transmission only receives ONE signal related to engine performance and that is the current flowing through the PCS (Pressure Control Solenoid) which is entirely controlled by the PCM. There is no TPS, RPM, Speed or anything else going to the trans. With 0 Amps of current, the trans will be at full line pressure, With 1 Amp of current it will be at its lowest line pressure.
The PCM controls this PCS current based on measurements of things like TPS, MAF, RPM and the volume of gas going into the injectors; it is summarized as "Load" which scan tools will show. So higher load => lower PCS current.

I agree with Frank that the load and resulting PCS current should be measured even before the transmission is removed so that it can be corrected if necessary and the new transmission isn't immediately damaged later.
For example if the scan tool shows "load" going up and down as it should, but the PCS current does not change, it would indicate that the PCM might be faulty with a shorted circuit which feeds the high current into the PCS resulting in low line pressure and instant 3/4 clutch failure.

 

My transmission guy did put a scanning tool on it and he did say the PCS is changing but he did not feel like it was changing enough. I did end up pulling the transmission Saturday. My guy moves to his cabin on the River during the summer and won't have much time to work on it very soon. He really wanted to tear it apart and do some testing to see if there is a mechanical issue while he has time. If he doesn't find anything mechanical he promised we would get the control issued figured out. He doesn't want to have to tear it apart again either. The rest of the story is I am running an ebay harness for the computer and transmission. I bought a used drive by wire pedal. I had a friend, not my transmission guy, who says he is good with HP Tuners set up the tune. Do you think I should ditch the junk yard computer and harnesses and just go with a Holley Terminator to start from scratch? I don't really know if that would give me any more control or not or if its worth the money. Again the motor runs great.