The ' resister accross the tran temp senser ' will
cause a TCC lock up at ( approx for 3.73 ) 28 mph in 2nd
40mph in 3rd, and does not affect OD ( 50 mph )
If you lock up the tcc in 3rd at 40 you will use the same or
slightly more fuel as OD with TCC not locked.
Also, it has been my experience , that the engine does not
run as smooth at rpm's below 1500 with TCC locked as
compared to a std shift at same low rpm's
I think std shift trucks have more dampening than the auto's.
The only reason I use the TCC forced lock up are,
When running a truck camper, OD does not unlock the
TCC, 3rd gear pulls 40 and up with TCC locked.
AND 2nd gear TCC locked in Steep back county mountains.
--- Also a good way to control tran Temps...in 2nd..
I'm looking to do this as well. I want to be able to tow in third with the TC locked up. I've read the blog and have a switch. On another thread, I've posted the wiring diagram for the trans. I'm still trying to CONFIRM the brown wire they're refering to...whether it's C11 and why in the diagram C11 has two wires going to it. I'd like to splice at the ECM rather than run long wires from the transmission.
It locks in 3rd gear at the same speed as OD,
the pcm uses drive shaft speed to determine when to lock.
Therefore the lock up rpm is higher in 3rd than OD
The higher the gear ratio and/or the larger the tire diameter. the higher the TCC lock up speed in actual mph
the indicated MPH may be lower than actual MPH with bigger tires.
I believe 3500 with stock tires locks around 42 MPH
3.73 with larger tires locks aroun 50mph.
AND 96 and newer can not be forced into TCC lockup
as per Heath Blog, Read Years applicable.
The PCM compares Transmission input to output speed.
it senses TCC locked when it expects it released, and
sets a fault that is not readable, This forces HIGH pressuere
shifts, you will feel it (note sometimes it sets a code, not always ) The hidden fault requires a ign off cycle to reset.
or a clear codes by a scan tool.
Let me see if I can get my head around this. I'm just trying to compare this to other things I've worked with in the past.
Do the speed sensors are providing a phase signal from the sensed rotation and then the ECM compares rotation of the input and output to determine a specific differential threshold to lock the torque converter?
If that's the case, by grounding the input sensor, wouldn't that achieve a threshold necessary to lock the TC?
Or am I missing it altogether? I'd really like to be able to tell the TC when I want it locked.
YES , missing it all together, Pardon my weak grammer.
To the best of my knowledge,
The PCM uses the drive shaft speed sensor to
determine lock up speed, I believe it is the same for all
vehicles, regardless of rear diff ratio. IE: at a specificed
Drive shaft rpm the PCM is 'allowed to lock the TCC', dependant on the other controlling parameters ( throttle position,gear selected , etc). The Lock up speed is the same for 3rd and OD , no lock up in 1st or 2nd gear.
The PCM compares the input speed sensor to the output sensor to determine if the TCC is Locked or unlocked
and compares that to the expected condition.
IE; IF input speed is not as expected for a TCC unlocked condition, a fault sets.
This is why forcing the TCC locked on OBD2 vehicles
causes a fault, and subquent full presure shifts.....
Don't mess with the sensors,
The PCM ( powertrain control module ) uses them to
determine all the shift points, pressures , etc...
I'm still digging around to get a handle on manually controlling the TCC.
Heath refers to the wire in the same fashion as the BD Torqloc instructions do - a brown wire although the Torqloc instructions further describe it as the "S" pin.
I have a 4L80E transmission wiring diagram. The 20 pin connector description identifies the "S" pin as TCC pwm and says the color is red/violet which doesn't match. Nor is there a brown wire in the 20 pin connector.
At the other end of the harness is the 63 pin CPC in which the CPC 28 location is also red/violet and is also TCC pwm.
The only reference in the diagram to a brown wire is in the db9 connector, pin 2.
Again, I'm trying to splice the line per Heath's instruction but would rather do it near the ECM and I'm trying to find the right wire. Geez, at this point, I'd even welcome a few wrong answers.
Qwestqaz, could you explain a bit further about the mod to your 96? What size resistor? You have the resistor in parellel with the transmission temperature sensor through a toggle in the truck, right? You tapped into the temperature sensor at the PCM? I assume you only lock the convertor when holding it manually in 2nd? Release the switch to allow it to shift to 3rd to avoid a full pressure shift?
1994 had the 4L60e as standard, with the 4L80E as optional in the 1500 and 2500 series vehicles - 3500 got the 4L80E, only.
1995 had 4L80E as standard behind all 6.5L Diesels.
4L60E had one more wire\pin T - Tan\Black from PCM pin E6 - for TCC lockup in the harness connector.
Temperature signal TFT on pin L had Blk\Yellow from PCM pin C9.
Some wire colors were different for the 4L60E transmission, and some 4L80E colors were different '94 to '95.
'94 4L80E pin S color is Dk Blue for the TCC PWM signal from PCM pin E11.
BUT - that wire cannot simply be grounded - the control is PULSE WIDTH MODULATED, is dictated by required TCC slip, which is calculated based on input speed sensor compared to output speed sensor.
The 4L80E TCC is never locked up - it is soft-applied only enough to meet engine-torque input requirement.
Even defeating the Transmission Fluid Temperature circuit on pin L - blk\Yellow from PCM C9 - only results in increased line pressure, with resultant firmer shifts and delayed unlock, but not increased lockup.
Purpose of all this was the hollow input shaft required for hydraulic apply for the TCC lockup function - heavy accel\braking resulted in broken input shafts.
That is why the TCC always seems to be unlocking when the accel pedal is released, or at any braking incident, now matter how slight.
Manual operation of the torque converter lock-up clutch in 1992-1995 trucks with the 4L80E
In our opinion, the factory transmission programming is quite well sorted out and works very well in the majority of applications. This factory programming affords torque converter lock-up clutch function only in 3rd and 4th gears. When towing uphill, with vehicle speeds that are below the converter unlock point, a significant amount of torque converter-induced transmission heat will build. Being able to hold the converter clutch in lock-up mode will prevent this unwanted heat build-up.
An annoying characteristic of the program is that it 'unlocks' the lock up clutch as soon as the throttle is released. The engine returns to a near idle speed and the truck just coasts down, without the benefit of being slowed by the engine.
A simple two-position toggle switch (Part #HDP1053) can be installed on the dash panel to provide a full, manual control of the lock up clutch. This will allow the manual locking of the torque converter in 2nd, 3rd and 4th gears and this is beneficial when towing.
Under towing conditions when vehicle speed must be low due to traffic and or road conditions, the converter can now be held in the lock-up mode while the trans is held in 2nd or 3rd gear.
To accomplish this modification, you will need a two-position, three pole toggle switch. The one we use us a Cole-Hersee #5584.
You must locate the 'BROWN' wire coming out of the electrical connector at the transmission. This wire runs to the ECM and controls the lock-up function in the transmission.
You will interrupt this brown wire at some point conveniently away from the electrical connection on the transmission. Splice a wire to both the transmission-end of this brown wire as well as the ECM-end of it. These two spliced-on wires will run to the new dash mounted switch. We usually mount the toggle switch in one of the ‘block-off’ plates on the dash, however it can be mounted virtually anywhere you like.
The switch has three connector poles. Fasten the ECM-side wire to one END pole and the transmission-end wire to the other END pole of the switch. Route a wire from the CENTER pole on the switch to a suitable ground source.
In one position, the switch connects the ECM to the transmission to achieve factory control of the converter lock-up clutch. In the other position, the switch grounds the wire running to the transmission to force a lock-up of the clutch.
That's it—you are done with this installation.
You will find that the engine does not enjoy being held down below about 1500 rpm and that this manual type control will require a bit of getting used to. If, for instance, you forget to switch the manual control off before you stop the truck, you will find that upon leaving a stop, the shift to 2nd, 3rd and 4th gears will be rather abrupt, as the torque converter will be locked up.
We hope that you find this info helpful, however you must feel free to contact us with any questions you may have regarding your 6.5. We are dedicated to support of the 6.5 and are always happy to help.
Questions about this or any Heath Diesel product? Feel free to contact us anytime 1-877 894 6266 or [email protected]
Dunno, Dan - a call to Bill Heath will always get informative data on his products.
He's a good man, reliable.
But - that scheme has been tried before by B&M, Trans-Go, and others, only to be discontinued after a very short interval.
The PWM Solenoid in the 4L80E is meant for variable duty-cycle pulsed service, so its resistance\impedance is considerably different than a solenoid meant for 100% duty cycle, which is either ON or OFF.
A PWM-rated solenoid coil will burn open if used in 100% duty cycle application.
I had considered a scheme using the 4L60E TCC solenoid, which isn't PWM controlled, but they're not similar.
Could be - and this is not word up - the '91 TCC was designed for 100% duty cycle apply, but was discontinued later due to - and this is word up - increased incident of input shaft breakage where engine-braking was normal, as in flat-bed, wrecker, bus, van, and dump-truck service.
Iirc, I researched that to find the early TCC to be PWM, but that was ca2000, after many intervening service upgrade bulletins (and some downgrade).
Again, a call to Bill would serve you best, because all other mfrs had long ago discontinued attempts to make it work.
I would not advise doing that scheme, tho, and am merely providing correct wiring info, along with precaution.
First, I do not have any knowledege about 80le in 93-95
applications , other than reading forums....
but some posts suggest that BD torque loc works on these
models, from installing a BD in my 96 I determined
that it will not work ( sets faults )on OBD2. also I believe
the BD forces the TCC locked by grounding the TCC
solenoid ( ala Heath method ) The BD has a speed
sensor this reverts the TCC back to normal operations
below a specific speed.
I do operate the truck with a TCC fooler circuit( The Resister accross the Temperature sense circuit,
( Search Posts ))
Yes It causes High Pressure shifts but it also allows
2nd gear lock up and early 3rd gear lock up,( previous
post this thread).
Yes, I have read the danger of the shaft breaking,
$$$I DO NOT SHIFT with high loads on engine, I shift
manually much like a Std shift. Also I down shift
prior to any hill which I think 3rd gear will be required,
ditto 2nd ,
I also do not load the engine completly untill the TCC
And I agree with the 'runs rough below 1500 rpm,
I believe (MHO)this is because the torque converter is not
weighted like a std shift, which appears to run quite
smoothely below 1500 rpm. That is a good reason
why, again IMHO, it is not wise to force a TCC lock up
with the 'Ground' switch, unless one keeps the rpm
above the 1500 rpm range...
JAC6695: there are threads with the complete info: I
will try to find the links, if not I will do a new thread
with the info.
I use the TCC lock up most the time when the truck camper
is loaded. 2nd through OD ( High drag, but not to much weight,3K lbs)
2nd gear use is usually limited to very step hills or
when accelerating onto Freeways.
O/D, I use the switch to keep from droping out of
TCC lock up. ( holds TCC lock up untill downshift )
3rd gear I use the TCC switch to gain another 10 mph
lower engage speed ( ie non interstate, varing speeds )
( See above $$$$ )
TCC lock up does not appear to save any fuel when driving localy, no load in truck,
A 50 ohm at PCM , through a switch, from temp sense
wire to ground and yes I manually shift gears.
I would post a schematic, but I have not figured out how to
cut and paste into the forum....
If anyone emails through private msg, I will try to repond with additional info/schmatics....
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