4L60-65E conversion to 4L80-85E using T42 TCM
07-25-2012, 08:32 PM
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4L60-65E conversion to 4L80-85E using T42 TCM UPDATE!!! After receiving a phone call on this article, I realized I never updated it when all issues were resolved.
It's been a while since this job so I will do the best I can to remember. I know I posted the correct fix someplace, but apparently not here. oops.
So due to GM's programming, they ramp up TCC PWM before commanding TCC Enable. So even though the 4L80E does not have a TCC enable solenoid, you still need to use a relay in place.
I have just completed upgrading a 4L65E trans to a 4L85E trans in a 2005 Chevy SSR with a 6.0 supercharged. I've had dificulty finding any decent tech articles. I will list here the things that need to be done, but I have some questions as well if there is anyone out there with the talent to answer my questions.
The transmission pin configuration between the 4L65E and the 4L85E are ALMOST identical!! The few changes that need to be made are prety simple.
For one, the 4L85E does not have a 3-2 downshift solenoid, nor a TCC control solenoid. and the wiring pin locations for the TCC/PWM solenoid are in different locations between the 2.
For two, Shift solenoid B (2-3) control pattern is EXACTLY backwards between the 4L65E and the 4L85E. So for instance the 4L65E D4 shift pattern is as follows.
-------4L60-65E----------------------------4L80-85E
D4 Shift Sol A---- Shift Sol B----------D4 SS-A-----SS-B
1st------ON---------ON-----------------ON--------OFF
2nd-----OFF---------ON ----------------OFF-------OFF
3rd------OFF--------OFF----------------OFF-------ON
4th------ON---------OFF----------------ON--------ON
As you can see, SSA stays the same. SSB is backwards. This apply's to ALL the SSB commands. Simple to correct.
Install a normally closed 4 prong relay. Wire the pink ignition switched 12V wire to one side of the coil, and the computers command wire for SSB to the other side. Connect the wire going to the SSB (towards transmission) to one of the load terminals, and the other load terminal to ground.
So now when the computer is commanding the solenoid OFF, it will be ON, and when it commands it ON, it will be OFF..
Now, at the transmission connector, you neet to change terminals. Remove the white 3-2 shift solenoid from cavity S and remove the brown wire for TCC/PWM from cavity U. Install the brown wire from cavity U into Cavity S. The white wire for 3-2 solenoid will not be used, but we need to trick the computer to think the 3-2 solenoid is still there to avoid trouble codes. (This next part is wrong) We will need to do the same with the TCC control solenoid wire (Tan-Black). Need to use a relay in place as well that is triggered by the tan-black but in series with the TCC-PWM signal.
Splice into the pink power wire on cavity E and branch off of that. Attach 2 1 watt 1000 ohm resistors to the branched off wire. Connect the disconnected white wire from the TCM for 3-2 control to one of the 1k resistors. Typical resistance of the 3-2 is 22.0 ohms. But hey are better able to handle the load when the circuit is energized. By using a 1000 ohm resistor, it drops current flow in that circuit to 12 mA and will not trigger any trouble codes.
It's been a while since this job so I will do the best I can to remember. I know I posted the correct fix someplace, but apparently not here. oops.
So due to GM's programming, they ramp up TCC PWM before commanding TCC Enable. So even though the 4L80E does not have a TCC enable solenoid, you still need to use a relay in place.
I have just completed upgrading a 4L65E trans to a 4L85E trans in a 2005 Chevy SSR with a 6.0 supercharged. I've had dificulty finding any decent tech articles. I will list here the things that need to be done, but I have some questions as well if there is anyone out there with the talent to answer my questions.
The transmission pin configuration between the 4L65E and the 4L85E are ALMOST identical!! The few changes that need to be made are prety simple.
For one, the 4L85E does not have a 3-2 downshift solenoid, nor a TCC control solenoid. and the wiring pin locations for the TCC/PWM solenoid are in different locations between the 2.
For two, Shift solenoid B (2-3) control pattern is EXACTLY backwards between the 4L65E and the 4L85E. So for instance the 4L65E D4 shift pattern is as follows.
-------4L60-65E----------------------------4L80-85E
D4 Shift Sol A---- Shift Sol B----------D4 SS-A-----SS-B
1st------ON---------ON-----------------ON--------OFF
2nd-----OFF---------ON ----------------OFF-------OFF
3rd------OFF--------OFF----------------OFF-------ON
4th------ON---------OFF----------------ON--------ON
As you can see, SSA stays the same. SSB is backwards. This apply's to ALL the SSB commands. Simple to correct.
Install a normally closed 4 prong relay. Wire the pink ignition switched 12V wire to one side of the coil, and the computers command wire for SSB to the other side. Connect the wire going to the SSB (towards transmission) to one of the load terminals, and the other load terminal to ground.
So now when the computer is commanding the solenoid OFF, it will be ON, and when it commands it ON, it will be OFF..
Now, at the transmission connector, you neet to change terminals. Remove the white 3-2 shift solenoid from cavity S and remove the brown wire for TCC/PWM from cavity U. Install the brown wire from cavity U into Cavity S. The white wire for 3-2 solenoid will not be used, but we need to trick the computer to think the 3-2 solenoid is still there to avoid trouble codes. (This next part is wrong) We will need to do the same with the TCC control solenoid wire (Tan-Black). Need to use a relay in place as well that is triggered by the tan-black but in series with the TCC-PWM signal.
Splice into the pink power wire on cavity E and branch off of that. Attach 2 1 watt 1000 ohm resistors to the branched off wire. Connect the disconnected white wire from the TCM for 3-2 control to one of the 1k resistors. Typical resistance of the 3-2 is 22.0 ohms. But hey are better able to handle the load when the circuit is energized. By using a 1000 ohm resistor, it drops current flow in that circuit to 12 mA and will not trigger any trouble codes.
Last edited by SwingShiftAuto; 04-28-2015 at 01:35 PM. Reason: spaces distorted chart.
07-25-2012, 11:43 PM
#2
Is the a reluctor difference between the 4L65E and the 4L85E for the output speed sensor.
I have not installed the input speed sensor. Is the T42 TCM set up to recognoze an input speed signal when programed for the 4L65E? I have the pin out for the T42 and can wire it, but if it's pointless, why bother?
Path of least resistance is wire it up like a factory 4L80e and put a 4L80e cal in the T42.
07-26-2012, 05:35 PM
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I just did a LS2 swap into my Colorado using a 2006 Trailblazer harness (E40/T42) and a 4L80E.
I did pretty much the same thing, I found some info on another forum. Used different ohm resistors and a second relay for the TCC apply. But the same concept.
Everything works as it should on mine after quite a bit of trial and error. Are you sure you have the right MPH in the tables now that your gear ratio is different with the 4L80E?
I did pretty much the same thing, I found some info on another forum. Used different ohm resistors and a second relay for the TCC apply. But the same concept.
Everything works as it should on mine after quite a bit of trial and error. Are you sure you have the right MPH in the tables now that your gear ratio is different with the 4L80E?
07-18-2018, 12:13 PM
#7
TECH Senior Member
You are replying to a 6-year old post... since the thread has not continued it is likely those posting in it are not around either.
