Home › Tuning › Transmission tuning

Transmission tuning for an LS or Gen V LT swap

Electronic automatics are run by the computer, so the tune decides how they shift and how long they live. LS and LT alike.

Last updated November 8, 2026

Tune checklist for your build: pick engine, computer, trans →

What the tune controls

On a 4L60E, the computer controls shift timing and line pressure. A calibration that firms up shifts is a key durability upgrade, because firm shifts reduce clutch slip and heat.
Hydraulic transmissions (TH350, TH400, 700R4) have no computer control. The 700R4's TV cable must be adjusted precisely; out of adjustment, it can shift too fast and burn up the clutches.

Who controls it

Transmission	Control and bolt-up notes
4L60E	Electronic — needs a computer that runs it: the factory PCM it was paired with, or a Holley Terminator X Max kit that includes the 4L harness. That harness is not compatible with a 4L6X from model year 1995 or before, because converter lockup and the downshift strategy changed year by year, and it is not recommended for a 4x4 with an electronic transfer case. A drive-by-wire Max kit with no transmission harness, such as 550-929, does not shift it. LS 4L60E flexplates use the 11.062 in converter pattern; LS-version 4L60Es use a 300 mm input shaft and an LS converter.
4L80E	Electronic — factory PCM, or a Holley Terminator X Max kit that includes the 4L harness. That harness is not compatible with a 4L6X from model year 1995 or before, because converter lockup and the downshift strategy changed year by year, and it is not recommended for a 4x4 with an electronic transfer case. A drive-by-wire Max kit with no transmission harness, such as 550-929, does not shift it. Uses the 11.5 in converter pattern, so you need a 4L80E-pattern flexplate.
6L80 / 6L90	Electronic — factory ECU/TCM, or Terminator X Max plus Holley's 558-499 6L80/6L90 kit for a 2007+ 6L80 or 6L90E (2WD only; needs Holley V3 software, build 100 or later).
TH350 / 700R4 / Powerglide	Most LS cranks sit about 0.400 in shorter than older GM engines: use a dished (or dual-pattern) flexplate with the 10.75 in converter pattern plus a converter adapter sleeve. Exception: 1999–2000 long-crank 6.0s — a TH350 works with a TH400 converter; a 700R4 has no easy fix short of a 2001+ crank.
TH400	Uses the 11.5 in converter pattern — the same as an LS that came with a 4L80E; space the factory 4L80E flexplate with an adapter.
Manual (T56 / TR6060 / TKX / TKO)	Needs an LS-specific bellhousing (factory T56 or aftermarket steel), clutch, flywheel and hydraulic release. The Tremec TKX is the most popular LS swap manual today; a T56 may need firewall/tunnel modifications.
8L90	Electronic 8-speed with its controller inside the transmission. We tune the engine and transmission side on supported applications; on a 2019+ Global B truck the computer needs HP Tuners' unlock first.
10L80 / 10L90	Electronic 10-speed with its controller inside the transmission; the Camaro ZL1 uses the 10L90. We tune the engine and transmission side on supported applications. A 2019+ Global B truck needs HP Tuners' computer unlock first.
8L45	Electronic 8-speed with its controller inside the transmission. We tune the engine and transmission side on supported applications.

Converter and cooling

Match the converter's stall to the cam, vehicle weight, gearing and tires. How to pick a stall speed.
Higher-stall converters make more heat; an external cooler helps. Separate cooler vs radiator cooler.

The details

Specifics depend on your computer and operating system.

Show all

Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: Terminator X Max controls 2007+ GM 6L80E/6L90E transmissions by communicating with the factory internal TCM over CAN; a dedicated 16-way connector plus a 12V/fused power harness (including solenoid and TCM power) is required, with the solenoid power source rated at a minimum of 5 amps.
Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: Basic 6L80E/6L90E TCM adjustments are done through the OBD-II port or the handheld: shift points, tire size, gear ratio, transmission relearn, diagnostic functions, and TCM OS selection. The Terminator X V3 software adds advanced control: virtual torque, virtual TPS, torque management, secondary mode, and tap shifting.
Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: After installing the Holley 6L80/90 harness, the internal TCM must be programmed and all software/firmware updates completed with uninterrupted battery power; the handheld prompts the user to choose an OS only after all updates finish.
Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: The 6L80/90 brake-switch input wire to the transmission connector must see +12V only when the brake pedal is applied and be wired to pin J4-B24 of the ECU; the park/neutral safety wire provides a TCM ground to the starter relay and must never be wired to +12V, which would damage the TCM.
Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: Transmissions are identified by a tag on the case: for a 6L80E the second character is C, for a 6L90E it is D. The pre-2010 TCM OS is 24270599, while the 2010+ OS is 24265260; the manual provides a year/model matrix so the correct calibration (car or truck, Corvette/Camaro vs Silverado) is selected.
Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: Selecting the Car calibration in the Holley handheld gives Sport Mode, while Truck gives Tow/Haul; 'Performance' selects OEM TCM tables modified by Holley for crisper shifting and 'Orig w/ Options' retains near-OEM shifting with options such as tap shift and sport mode available.
Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: Holley's handheld shift-point adjustments cover all five upshifts (1-2 through 5-6) in MPH and RPM, but tire size and gear ratio values must match between the handheld and the Terminator X software; the software values calculate speed while the TCM values control shifting, so a mismatch produces incorrect speed readings or wrong shift behavior.
Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: Holley's tap shift inputs are ECU pin J4-B8 (upshift) and J4-B9 (downshift), selectable as +12V or ground; the ECU turns momentary taps into CAN gear increment/decrement commands. On truck calibrations, tap mode sets the highest available gear (for example D6) and automatic shifting continues; on car calibrations below D6 it behaves more like manual paddle control.
Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: The Holley ECU can reduce torque during shifts through timing retard or drive-by-wire throttle reduction; on naturally aspirated combinations this usually means a mild ignition retard during upshifts and downshifts, while aggressive boosted tunes may use electronic-throttle torque reduction for large turbo/supercharged torque drops.
Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: The Holley 6L80/90 torque reduction request table spans -999.0 to 0.0 ft-lb. Tuning guidance: if shifts are overly aggressive or flare, increase torque reduction; if there is hesitation or a sag during the shift, reduce it.
Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: Virtual TPS compensates for airflow differences between OEM and aftermarket throttle bodies because the TCM's partial-throttle shift schedules are TPS-based. A drive-by-wire body may show 30-40% TPS at a given airflow where a 4150-style body shows 5-15%, and that mismatch can move low-throttle shift points by 10-20 mph. Keep the virtual TPS endpoints at 0% and 100%; changes work best below 50% TPS.
Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: Virtual torque tells the TCM how to shape shifts and defaults to a fuel-flow-derived estimate. Adjust the offset in 5 ft-lb steps for soft/slipping or overly firm shifts, with the multiplier's neutral point at 0%. A closed-throttle braking offset acts below 10% TPS with the brake applied (default -65.0 ft-lb) and an A/C torque loss offset defaults to 8.0 ft-lb.
Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: The virtual torque table spans -999 to 999 ft-lb and can be made TPS- or boost-referenced; adding virtual torque in boosted-load cells commands firmer shifts to prevent clutch slip. A table-driven virtual torque avoids the effects of fuel corrections and temperature-based enrichments present in the default fuel-flow estimate.
Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: TCM torque requests can occur during upshifts, downshifts, and torque converter clutch events. Torque Converter Clutch Lock/Unlock during shift tables define whether the TCC stays applied across shifts for each gear change (1-2 through 5-6), in both normal and cruise modes.
Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: After any major transmission calibration change on a 6L80/6L90, a transmission relearn (adaptive reset) should be performed so the TCM relearns clutch fill volumes and shift timing; Holley exposes this in the handheld under transmission diagnostics.
Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: In the Holley 6L80/90 setup, raising the virtual TPS value raises partial-throttle shift MPH and lowering it reduces shift MPH; it's most useful below 50% TPS. Don't raise low-throttle shift points without supporting engine calibration changes.
P01, P59, E38, E67; LM7, LQ4, LQ9, LS1, LS2, LS3; 1999-2013: HP Tuners' TCC Lock During Shift parameter controls whether the converter clutch stays applied across a gearshift; lock-through-shift is extremely hard on the transmission and the TCC.
P01, P59, E38, E67; LM7, LQ4, LQ9, LS1, LS2, LS3; 1999-2013: HP Tuners provides separate TCC apply/release speed tables for Normal, Cruise, Performance, Hot, 4WD Low, and Tap Up/Tap Down modes, plus dedicated WOT apply/release schedules; the apply/release tables are indexed by TPS and gear.
P01, P59, E38, E67; LM7, LQ4, LQ9, LS1, LS2, LS3; 1999-2013: The TCC Release TPS table defines how much throttle is needed to unlock the converter at a given speed and gear, and HP Tuners also provides maximum and minimum TCC duty-cycle tables that vary with desired line pressure and transmission oil temperature.

Transmission and torque management settings

Values depend on your computer, operating system and combination. Use them as reference points, not settings to copy.

Show all

Transmission and torque management

HP Tuners; GM V8: Transmission torque management parameters define how the PCM reduces engine power via spark retard to protect the transmission; changing or disabling these values can reduce transmission life or damage the transmission.
HP Tuners; GM V8: The Torque Reduction vs Torque vs Shift tables (Normal, Performance, Downshift) define the percentage torque reduction applied during shifts.
HP Tuners; GM V8: HP Tuners provides separate torque-reduction enable switches for upshifts, closed-throttle downshifts, power downshifts and garage shifts, plus a Torque Reduction Master Enable (not available in all calibrations).
HP Tuners; GM V8: Transmission Abuse Mode is enabled when engine RPM exceeds the Abuse Mode RPM value (or TPS% exceeds its threshold if RPM is below it), and is disabled above the Abuse Mode Speed or below the Min Input RPM; it applies Abuse Torque Reduction % vs RPM for the Abuse Mode Duration vs Trans Temp.
HP Tuners; GM V8: TCC Limit Torque Reduction Max Torque is the maximum TCC limit torque, and should be set higher than maximum engine torque when the TCC limit is disabled.
HP Tuners; GM V8: The TCC Limit Torque Reduction Master Enable is the master enable/disable for the transmission TCC limit torque reduction calculations.
HP Tuners; GM V8: Stall torque mode is enabled when RPM is above the Stall Torque Enable RPM value, and disabled when RPM falls below the Stall Torque Disable RPM value.
HP Tuners; GM V8: The HP Tuners VCM Controls transmission cleaning function requires engine idling, vehicle stationary, selector in Park, and transmission temperature between 70-110°C.
HP Tuners: The transmission force motor (pressure control solenoid) is a relief valve that requires current to reduce line pressure: the higher the current, the lower the resulting line pressure.
HP Tuners: The 'Desired Shift Time' tables (Normal and Performance/Tow-Haul, plus adders) define the desired shift time for each part-throttle shift.
HP Tuners: The Base Shift Pressure tables return the pressure offset applied to the Force Motor Current table axis; increasing the values firms the shift, and the valid value range is 0 to 96.
HP Tuners: The Upshift and Downshift Pressure Modifier tables add positive or negative pressure depending on torque and transmission temperature; increasing them with positive values firms the shift, and zero has no effect.
HP Tuners: Max Line Pressure is the maximum desired line pressure allowed and acts as a clamp on any shift table value before it is used on the Force Motor Current table.
HP Tuners: The 'Steady State Pressure Offset - TCC On' parameter adds to line pressure when the torque converter clutch is on.
HP Tuners: Steady state pressure adapt is counter-driven: the 'Steady State Adapt Up Count Thresh' moves adapt pressure up when the slip counter exceeds the threshold, with a mirror down threshold.
HP Tuners; GM V8: After upgrading the TCM, you'll access key parameters, shift pressures, and torque management to optimize performance.

What we recommend

Run the 4L60E, not a 700R4. A 700R4 lives or dies on TV cable geometry, and there's no truly good way to drive it from an LS throttle body. The donor 4L60E bolts in the same, needs only ~6 wires, and gets its shift points and pressures set in the same session that deletes VATS.

How to do it

Check this first

If you already have a 700R4, verify TV geometry at the throttle arm (about 1-3/32 in radius from the shaft center) before driving it.

Try this, then this

Take the donor 4L60E with the engine. — It bolts in the same, the PCM handles shifts and pressures, and VATS delete plus shift points happen in one session.. Worked if: Trans shifts are set in the tune with no cables to adjust.
If you must run the 700R4, buy the Bowtie Overdrives TV kit and set the geometry exactly. — Wrong geometry burns the 3-4 pack in miles.. Worked if: Line pressure rises correctly off idle and the trans lives.

Key numbers

What	Value
TV cable controls line pressure and shifts	Controls line pressure, shift feel, part-throttle downshifts, and detent downshifts; improper adjustment causes premature failure
700R4 behind an LS needs a TV kit	Bowtie Overdrives throttle valve cable kit required; linkage needed slight modification on an LM7 swap
TV cable is a known pain on LS engines	One builder went to a manual valve body just to ditch it

Every option we know of

Maker / product	Fits	Where	Status / notes
Bowtie Overdrives TV cable correction kit for 700R4 behind LS	700R4/200-4R with aftermarket throttle bodies	bowtieoverdrives.com	active May still need slight linkage modification
Lokar Aftermarket TV/kickdown cable kits	700R4 swaps	lokar.com / Summit	active
GM Donor 4L60E from the same pullout	Bolts in the same as a 700R4; PCM-controlled	donor vehicle	used None of the TV cable problems

Prices are approximate as of September 2026. We list every option we know of, including small shops and used parts we can't link to. Confirm fitment with the seller.

Time and cost: TV kit roughly $100-200; a 4L60E from the donor is effectively free with the pullout.

Size the trans to the power. A stock 4L60E won't live forever in the mid-300s hp, ~400 needs a decent build, and nitrous, boost or a stroker points to a 4L80E. The 80E costs about 50-60 lbs and some fuel mileage, so choose it for power or towing, not by default.

How to do it

Check this first

Be honest about the power goal and the use (street, nitrous, boost, towing) before choosing.

Try this, then this

Stock or mild street combo: run the donor 4L60E. — Lightest, least drag, and it bolts in.. Worked if: It lives at your power level.
Around 400+ hp: build the 4L60E to a 450-500 rwhp rating. — A stock 60E won't live forever up there.. Worked if: Shifts stay crisp under power.
Nitrous, boost, stroker, or towing: go 4L80E, stock or with an HD-2. — Handles 450-500 lb-ft stock and far more with a shift kit.. Worked if: Trans survives the combo; accept the weight and drag.

Key numbers

What	Value
Published transmission weights	4L80E 178 lb; 4L60E about 135-140 lb (delta ~40 lb)

Every option we know of

Maker / product	Part #	Fits	Where	Status / notes
Various builders Built 4L60E (rated 450-500 rwhp)		Street LS combos to ~500 rwhp	transmission shops	active Won't live forever in the mid-300s hp stock
GM Stock 4L80E		Nitrous, boost, stroker, towing	junkyard / donor	used Costs ~40 lb and 20-30 hp of drag vs a 4L60E
TransGo HD-2 shift kit for 4L80E	HD-2	4L80E	Summit / dealers	active

Prices are approximate as of September 2026. We list every option we know of, including small shops and used parts we can't link to. Confirm fitment with the seller.

Time and cost: Built 4L60E roughly $2,000-3,500; junkyard 4L80E plus swap parts varies; HD-2 kit roughly $100-150.

Segment swap the 4L80E. Selecting 4L80E in HP Tuners (v2.4 or newer) works for some, but PIDs like converter slip can read wrong and shifts can be harsh. We recommend a segment swap from a donor 4L80E file instead; E38/T42 combos can't do it and need the Express van TCM flash.

How to do it

Check this first

Identify the PCM/TCM generation: P01/P59 can segment swap; E38/T42 cannot and needs the TCM flash.

Try this, then this

On a P01/P59 PCM, do a proper segment swap from a donor 4L80E file. — It replaces the trans and trans-diagnostic segments with real 4L80E logic instead of just flipping a selector.. Worked if: Shifts are clean and converter-slip PIDs read correctly.
On E38/T42, flash the TCM with a year-matched 4L80E calibration (e.g., 2008 Express Van, TCM OS 24239927). — No room for a segment swap in that memory.. Worked if: TCM controls the 4L80E with correct shift behavior.

Key numbers

What	Value
Documented Express-van TCM flash	2008 Express Van 4.8L tune, TCM OS 24239927; costs 2 credits to license
T42 can be programmed for 4L65 or 4L80	Repin the trans connector; reprogram E38/T42 with a 2008 year-matched 4L80E calibration

Time and cost: 2 HP Tuners credits to license the TCM file; tuner time for the swap.

Sort 4L80E wiring and converter bolts. Repin the existing trans connector and run two wires for the extra speed sensor rather than using an adapter harness. The 4L80E converter uses 6 bolts against a 3-hole 4L60E flexplate, so drill the flexplate or order a 3-lug converter.

How to do it

Check this first

Confirm which PCM strategy you are running (4L60E PCM with relay logic vs 4L80E PCM) — it decides whether the ISS gets wired.

Try this, then this

Repin the existing trans connector for the 4L80E and run the two ISS wires. — Cleaner and cheaper than an adapter harness, and documented to work.. Worked if: No trans codes and the ISS reads in the scanner.
Solve the converter bolts: drill the flexplate or order a 3-lug converter. — 6-bolt 11.5-inch converter vs 3-hole flexplate — they don't mate as-is.. Worked if: Converter bolts up centered and tight.

Key numbers

What	Value
Repin, don't adapt	The TCM/trans connector plug can be repinned for use with a 4L80
Two wires for the input speed sensor	With a 4L80E PCM you add the wires for the input speed sensor; with a 4L60E PCM and relay logic you skip the ISS
4L60E plug can be reused with wiring changes	Change the wiring and add ISS wiring and plug

Every option we know of

We may earn a commission when you buy through links on this page.

Maker / product	Part #	Fits	Price	Where	Status / notes
Hughes HP4004 flexplate + HP3795 LS adapter	HP4004 / HP3795	LS crank to older trans bolt patterns		Hughes dealers / Summit	active
Converter builders 3-lug 4L80E converter		4L80E with a 3-hole 4L60E flexplate		Yank / B&M / TCI / local shops	active
DIY Drill the 4L60E flexplate for the 6-bolt 11.5 in pattern		4L80E converter on a 4L60E flexplate	free		DIY Must be drilled accurately and balanced
Hughes Flexplate for bolting older-pattern transmissions to an LS	HP4004
Hughes LS1 crank adapter/spacer	HP3795			Buy

Prices are approximate as of September 2026. We list every option we know of, including small shops and used parts we can't link to. Confirm fitment with the seller.

Time and cost: Wiring time plus a flexplate or converter change; no expensive harness needed.

Match stall to cam and use. 2200-2500 stall is a good balance for a stock or mild-cam engine, and 3500-3600 is the practical daily-driver ceiling (drop to ~3200 in heavy traffic). Always add a transmission cooler with any converter swap.

How to do it

Check this first

Know your cam's advertised duration — stall follows the cam, not the other way around.
Check trans temps after the swap; heat is the tell that the stall is wrong or the cooling is short.

Try this, then this

Stock or mild cam: 2,200-2,500 stall. — Matches mild cams and keeps street manners and temps sane.. Worked if: Drives like stock until you stand on it.
Bigger cam: step stall with advertised duration, up to ~3,500-3,600 for a daily. — The converter has to let the engine reach its powerband.. Worked if: Launches in the powerband without excessive slip.
Always add a transmission cooler with any converter swap. — Slip makes heat, and heat kills transmissions.. Worked if: Temps stay in the 160-200 range in normal driving.

Key numbers

What	Value
Street/strip stall range	2,500-3,500 rpm for most street and street/strip combos

Every option we know of

Maker / product	Fits	Where	Status / notes
B&M HoleShot and Tork Master converters	Street/strip LS combos	Summit / dealers	active
Yank Street/strip converters (e.g., 3600 stall units seen in LS trucks)	LS combos	yankconverters.com / dealers	active
TCI BreakAway converter (2200-2400 stall recommended by a builder for a cammed Bronco)	Street/strip	tciauto.com / Summit	active
Broader Performance Custom converters built to your combo	Any	broaderperformance.com	active

Prices are approximate as of September 2026. We list every option we know of, including small shops and used parts we can't link to. Confirm fitment with the seller.

Time and cost: Converter roughly $400-1,200+ depending on brand and build; cooler roughly $60-200.

Tighter converters for boost. A 3800 billet stall is generally too loose for boost and will blow through; go tighter. A stock 4L80E converter is acceptable at modest boost around 10 psi.

How to do it

Check this first

If the converter blows through (RPM flares without acceleration) under boost, the stall is too loose.

Try this, then this

For boost, order the converter tighter than you would for the same cam NA. — Boost multiplies torque; a loose converter blows through and makes heat.. Worked if: Converter couples without flaring under boost.
Treat a stock 4L80E converter at ~10 psi as temporary. — Builders report stock 80E converters don't love boost.. Worked if: Plan the restall before it becomes the weak link.

Key numbers

What	Value
Stock 4L80E converters and boost — a caution	One builder: stock 4L80E converters don't like boosted engines

Every option we know of

Maker / product	Part #	Fits	Price	Where	Status / notes
Yank / B&M / TCI / converter shops Tighter restalled converter for boosted combos		Turbo/supercharged LS		dealers / local converter shops	active A restall of your existing converter is often cheapest

Prices are approximate as of September 2026. We list every option we know of, including small shops and used parts we can't link to. Confirm fitment with the seller.

Time and cost: Restall roughly $200-400; new boosted-spec converter $800-1,500+.

Off-road rigs need a big converter. Around 2,200-3,000 stall works off-road, and expect 500+ rpm less effective stall in low range. A 12-inch converter at ~2,200 stays cooler than a small 10-inch unit; run a good trans cooler with a fan.

How to do it

Check this first

Watch trans temps on the trail — 160-200 is normal; fluid life halves every 20 deg above 175.

Try this, then this

Run a big-diameter, low-stall converter (around 2,200-3,000) for off-road. — Bigger diameter is more efficient and stays cooler; low stall suits slow trail speeds.. Worked if: Temps stay sane on the trail.
Fit a good cooler with an electric fan. — In 4x4 low the converter sits in stall making heat with no airflow through the radiator.. Worked if: Fluid temps stay in the 160-200 range while crawling.

Key numbers

What	Value
Trail rigs want a low-stall stock-style converter	Slow-speed trail use benefits most from low stall
Slip makes heat — the biggest enemy of trans fluid	Don't install too high a stall; slippage produces heat
Higher stall needs a bigger cooler	Going to a higher stall usually necessitates a larger cooler
4x4 low = converter in stall stage + no airflow	Tons of additional heat; an additional cooler with a large electric fan is best for crawling

Every option we know of

Maker / product	Part #	Fits	Price	Where	Status / notes
GM Stock-style 12-inch low-stall converter		Off-road LS trucks		junkyard / parts stores	used/new A small 10-inch high-stall is the wrong tool here
Aftermarket Plate-and-fin trans cooler with electric fan		Any		Summit / dealers	active Fan matters at crawling speeds with no airflow

Prices are approximate as of September 2026. We list every option we know of, including small shops and used parts we can't link to. Confirm fitment with the seller.

Time and cost: Cooler with fan roughly $100-250; converter per the stall ladder.

Wire the brake switch for TCC. Use a brake switch with two sets of contacts (e.g. NAPA SL186) or relay-invert the signal so the converter unlocks properly. On a 6L80, confirm the TCM and ECU years are compatible; pre-2012 tap shifting is slow, while a 2012+ TCM can take the Corvette/ZR1 tune.

How to do it

Check this first

Confirm the converter locks at cruise and unlocks the instant you touch the brake.
On a 6L80 swap, check the TCM and ECU years/OS compatibility before buying.

Try this, then this

Wire a dual-contact brake switch (or relay-invert the signal) so the PCM sees brake apply. — The converter must unlock when you brake.. Worked if: TCC unlocks instantly on brake touch and relocks at cruise.
On a 6L80, match TCM and ECU years/OS and flash a 2012+ calibration for tap shift. — Year mismatch won't pair; pre-2012 tap shift is slow.. Worked if: Tap shift responds promptly and the trans pairs with the ECU.

Key numbers

What	Value
Tap shift needs a Corvette calibration	Programmed with a Corvette calibration to activate tap shift
TCM/ECU year compatibility around 2008-2009	TCM module change ~2009; pre-change TCM can't pair to post-change ECM — check OS compatibility

Every option we know of

Maker / product	Part #	Fits	Price	Where	Status / notes
BP Automotive TCC brake switch		Gen III and E40 24x swaps with electronic automatics	$25	bp-automotive.com	active NOT needed for Gen IV 58x or Gen V
NAPA Brake switch with two sets of contacts	SL186	Swaps needing a dual-contact brake switch		NAPA	check Confirm the part number against a NAPA lookup before publishing
DIY Relay-inverted brake signal		Any swap where the brake signal polarity is wrong for the PCM	relay cost		DIY
BP Automotive Dual-pole brake switch for TCC unlock, $25	TCC brake switch

Prices are approximate as of September 2026. We list every option we know of, including small shops and used parts we can't link to. Confirm fitment with the seller.

Time and cost: Brake switch $25; 6L80 calibration work is tuner time.

Based on what we've seen work across our own builds, our friends' builds and the wider LS community, reviewed by our lead shop tuner (over 20 years of LS and LT tuning experience). Every combination is different, so use at your own risk and check our safe tuning limits before any wide-open pass.

← Fuel, E85 & boost · Next: Who tunes it? → · Tune checklist for your build

Something wrong on this page? Tell us