Shift complaints on a V6 Chevy Equinox come in four flavors: a bang going into Drive or Reverse, a harsh or late upshift, a flare where the RPM runs up between gears, and a shudder or bump that the owner just calls "shifting funny." The 6T70 gives you a way to sort all four. Every gear uses two clutches, GM's own symptom tables are organized by clutch, and the scan tool will tell you whether the computer or the hardware is at fault. This is how we work through a shift-quality Equinox at the bench before anybody sells it a transmission. Numbers in brackets point to the Sources list at the bottom.
First, confirm what is in it
Only the V6 Equinox has a 6T70. GM's wave plate bulletin lists the 2008-2009 Equinox with the 6T70/75 under RPO MH2 (FWD) or MH4 (AWD) [1], and bulletin 18-NA-358 covers the 2014-2017 Equinox under RPO M7U or M7W [2]. Four-cylinder Equinoxes use the 6T40/45 family, which has its own bulletins and calibrations, so do not apply 6T70 fixes to a 2.4L truck.
The generation matters as much as the RPO. ATRA notes that the M7U/M7W units got the Gen 2 update for the 2013 model year [4]. Sonnax documents what changed in the valve body: Gen 2 dropped the TEHCM pressure switches (the switch films were distorting and setting codes), redesigned the clutch regulator valves around the missing switch circuits, added a No. 10 checkball, went from three to six solenoid dampers on the top cover, and changed the 2-6 regulator, the clutch boost valve, the actuator feed limit valve and the 4-5-6 accumulator spring [5]. Gen 1 and Gen 2 separator plates are not interchangeable [5]. A shift-quality fix that is right for one generation can be wrong for the other.
Step 1: Codes, fluid, and engine torque
Pull codes from the ECM and the TCM before you drive it. A shift complaint with a P0776 is a different job from a shift complaint with no codes. On the 2008-2009 truck, P0776 (Clutch Pressure Control Solenoid 2 Stuck Off) with a harsh or flared shift into 3rd or 5th is the classic broken 3-5-R wave plate, and GM lists P0777, P2723, P0717, P0716, P2715 and P2714 as companion codes [1].
Engine codes matter too. GM's harsh garage shift table starts with the engine: if the engine controller reports inaccurate torque to the transmission, the TCM commands high line pressure and every engagement gets hard [3]. A misfire also shows up as a "shift shudder" on the 2014-2017 trucks, and 18-NA-358 has you rule it out before touching the valve body [2].
Then check the fluid hot. ATRA's procedure is a level surface, engine idling, transmission fluid temperature between 180 and 200 degrees F [4]. The fluid is DEXRON VI; GM's 3-5-R repair calls for nine quarts of part 88861037 [1]. Low fluid aerates the pump and makes apply pressure inconsistent, which feels like random harsh and soft shifts.
Step 2: Name the clutch with the apply chart
Every 6T70 gear is two clutches, so the shift that feels wrong points at the oncoming clutch. Sonnax's apply chart [6]:
| Gear | Clutches applied |
|---|---|
| 1st | 1-2-3-4 + low one-way clutch (low/reverse for engine braking) |
| 2nd | 1-2-3-4 + 2-6 |
| 3rd | 1-2-3-4 + 3-5-R |
| 4th | 1-2-3-4 + 4-5-6 |
| 5th | 3-5-R + 4-5-6 |
| 6th | 2-6 + 4-5-6 |
| Reverse | 3-5-R + low/reverse |
So a harsh 1-2 and a harsh 5-6 both put the 2-6 clutch on; a bad 2-3 and a bad 4-5 both put the 3-5-R clutch on; a bad 3-4 is the 4-5-6 clutch. GM's diagnostic symptom tables for the 6T70/6T75 are built exactly this way, with separate pages for "Harsh or Late Second and Sixth Shift," "Harsh or Late Third, Fifth, and Reverse Shift," "Harsh Fourth, Fifth, and Sixth Shift" and "Harsh Garage Shift" [3].
Step 3: Watch it on the scan tool
Drive it with Commanded Gear, Gear Ratio, Transmission ISS, Transmission OSS, TFT and TCC Slip Speed on screen. GM's road test says that during an upshift at a steady 15 to 20 percent throttle, the shift should be felt, or engine speed should change, within 1 to 2 seconds of Commanded Gear changing [3]. Longer than that is a late shift. If engine RPM rises while Gear Ratio is between values, that is a flare: the offgoing clutch let go before the oncoming clutch held.
Also watch TCC Slip Speed. GM's limit is under 100 RPM once the converter clutch is commanded on; more than 100 RPM for over 6 seconds is a converter problem, not a shift problem [3]. A lot of "shudder on the 2-3 shift" complaints are really the converter clutch, and 18-NA-358 makes you check TCC slip during the event before replacing anything [2].
Harsh garage shift (Park to Drive or Reverse)
GM's checks for a harsh garage shift [3]:
- Line pressure at idle should be below 800 kPa (116 psi). Higher than that, look at engine torque reporting first, then the pressure regulator.
- Lower valve body: stuck valves, particularly the boost valves.
- 1-2-3-4 and low/reverse clutch wave plates: damage or fatigue. A flattened wave plate means no cushion.
- Low/reverse piston: the air bleed positioned correctly and not plugged.
- Low/reverse one-way clutch and the input carrier ring gear: stripped or sheared splines, which feel like a clunk rather than a hard apply.
Check line pressure with a gauge in the line pressure test hole and step the Line PC solenoid with the scan tool's output controls; GM's procedure uses roughly 200 kPa steps in Park or Neutral below 1500 RPM, and the test plug goes back in at 12 Nm (106 lb in) [3].
Harsh or flared 2-3 and 4-5 shifts: the 3-5-R clutch
This is the most common Equinox shift complaint we see. GM's symptom table for a harsh or late 3rd, 5th and reverse shift lists five things, all in the 3-5-R clutch: plate and backing plate surface finish, plugged oil passages or air bleed in the 3-5-R/4-5-6 housing, damaged or leaking piston seals, a warped housing, and a fatigued wave plate [3].
On a 2008-2009 Equinox the wave plate is the first thing to suspect. Bulletin 09-07-30-012F covers a slip, flare or harsh shift into 3rd and/or 5th, often with no reverse and P0776 [1]. When the wave plate breaks, the piston over-strokes and the pieces circulate through the unit. GM's repair is the updated waved plate 24254103, separating the case halves to clean out the debris, and replacing the pump fluid filter and the control solenoid filter plate [1]. GM also says not to replace the TEHCM for a DTC unless service diagnostics call for it [1]. Sonnax lists a worn 3-5-R clutch regulator bore as a cause of 2-3 and 4-5 flare, delayed or slipping reverse and burned 3-5-R clutches on Gen 1 valve bodies [5], so check the bore if the pack is burned and the plate is intact.
Harsh or flared 3-4 shift: the 4-5-6 clutch
GM's harsh 4th, 5th and 6th table is all 4-5-6 clutch: leaking piston seals, a plugged dam air bleed, a fatigued piston spring, leaking dam seals, plate surface finish, and porosity, seal groove damage or plugged passages in the 3-5-R/4-5-6 housing [3]. On the valve body side, Sonnax ties a worn Gen 1 4-5-6 accumulator piston bore to 3-4 flare, harsh 3-4, slipping gears and burned 4-5-6 clutches [5]. Gen 2 changed that accumulator spring and retainer [5], so make sure the parts match the unit.
Harsh 1-2 or 5-6 shift: the 2-6 clutch
For a harsh or late 2nd and 6th, GM's table checks the 2-6 clutch plates and backing plate for wear or poor finish, the 2-6 piston cushion spring for fatigue, and the 2-6 piston, its seals and its return spring in the case cover [3]. Sonnax's oversized 2-6 clutch regulator kit is aimed at 1-2 and 5-6 flare, 2nd and 6th slip, burned 2-6 clutches and erratic shift timing on Gen 1 valve bodies [5]. GM's harsh or late 1-2-3-4 table, which you will use for harsh engagements in the lower gears, points at the 1-2-3-4 piston and seals, return spring, wave plate and the case passage seal [3].
2014-2017: shudder, flare and harsh shift from the valve body
GM bulletin 18-NA-358 covers 2014-2017 Equinox units (RPO M7U, M7W) with a launch shudder in 1st, a shudder in 4th, or a 2-3 or 3-2 shudder that may come with flare, slide, slip or a harsh shift [2]. GM blames debris in the upper and/or lower valve body or scored valves. Once misfire and TCC slip are ruled out, GM has you try to reproduce the launch shudder with a power brake in first for 5 seconds or less; if it reproduces, replace both the upper (24281084) and lower (24257450) valve bodies together [2]. GM states TEHCM replacement has not fixed this concern [2]. Check the speed sensors for debris; debris there means an internal failure, not a valve body job [2].
Gen 1 pressure switches: erratic shifts with codes
On a 2008-2012 Gen 1 unit, the TEHCM pressure switches report clutch regulator position to the TCM for adaptive learning. Sonnax lists them as opening at 8 psi and closing at 12 psi, with a high failure rate from delamination and contamination, typically setting P0752, P0872, P0877 and/or P0989 [6]. A switch that lies sends the adapts chasing the wrong numbers, and the shifts get harsh or flare in ways that look mechanical. The switches can be serviced instead of replacing the whole TEHCM. Gen 2 units have no pressure switches, so this does not apply to a 2014-2017 truck [5].
After any repair: reset and relearn
A correctly repaired 6T70 will still shift badly on old adapts. GM calls for Transmission Adaptive Values Learn after internal service or overhaul, valve body repair or replacement, control solenoid valve assembly replacement, a TCM software update, or any service for a shift quality concern [3]. The conditions: drive wheels blocked, parking and service brake applied, zero throttle, TFT between 70 and 100 degrees C (158-212 F), and Park to Reverse three times to purge air from the reverse clutches [3]. Run it from the TCM's Configuration/Reset Functions menu; when it finishes the transmission stays in neutral until you key off, let the TCM power down and restart [3]. If it will not run, GM's list includes active DTCs, a misadjusted Park/Neutral switch, and line pressure that cannot reach 1000 kPa [3].
On Gen 2, ATRA explains that the TCM also learns clutch fill volume (CP Learn) during steady driving: the 4-5-6 clutch in 3rd, the 1-2-3-4 and 2-6 in 5th, and the 3-5-R in 6th, and it aborts the learn on rough roads [4]. Drive it on smooth pavement, holding each of those gears, before judging the shifts.
Quick reference
| Complaint | Clutch / circuit | First things to check |
|---|---|---|
| Harsh into Drive or Reverse | Line pressure, 1-2-3-4, low/reverse | Engine torque codes, idle line pressure under 800 kPa, boost valves, wave plates [3] |
| Harsh/flare 2-3 and 4-5, weak reverse | 3-5-R | Wave plate, P0776, bulletin 09-07-30-012F [1][3] |
| Harsh/flare 3-4 | 4-5-6 | Piston and dam seals, accumulator bore [3][5] |
| Harsh/flare 1-2 and 5-6 | 2-6 | Cushion spring, 2-6 regulator bore [3][5] |
| 2014-2017 shudder with flare or harsh shift | Valve body | 18-NA-358, both valve bodies [2] |
| Erratic shifts with P0752/P0872/P0877/P0989 | Gen 1 TEHCM switches | Pressure switch service [6] |
| Bad shifts after any repair | Adapts | Transmission Adaptive Values Learn [3] |
Shop the part for this fix: 6T70 master rebuild kit
When the harsh or flared shift turned out to be a burned 3-5-R, 4-5-6 or 2-6 pack, this CoreTransmissionParts master kit has the frictions, steels, gaskets and seals for the overhaul. Match the generation to your unit.
View the 6T70 master rebuild kit at CoreTransmissionPartsLooking for something else? Browse all 6T70 parts at CoreTransmissionParts.
Need parts for this job?
Our 6T70 parts page has valve bodies, solenoid kits, Gen 1 and Gen 2 rebuild kits and clutch drums for the V6 Equinox, all on our own checkout. For fluid specs across every unit, see the transmission fluid spec chart.
FAQ
Why does my Chevy Equinox shift hard?
On a V6 Equinox with the 6T70, a hard shift into Drive or Reverse usually means high line pressure, a stuck boost valve or a fatigued wave plate, and GM says inaccurate engine torque reporting can make the TCM command high line pressure. A hard or flared 2-3 and 4-5 shift points at the 3-5-R clutch, and on 2008-2009 trucks that is often the broken wave plate in GM bulletin 09-07-30-012F. Check codes and hot fluid level first.
What causes a 6T70 to flare between gears?
A flare is engine RPM running up because the oncoming clutch is late. Use the apply chart: a 2-3 and 4-5 flare is the 3-5-R clutch, a 3-4 flare is the 4-5-6 clutch and its accumulator, and a 1-2 and 5-6 flare is the 2-6 clutch. Worn clutch regulator bores in the valve body and failed Gen 1 pressure switches can also cause flares.
Do I need to reset the transmission adapts on a 6T70?
Yes. GM calls for Transmission Adaptive Values Learn after internal repair, valve body or solenoid work, a TCM software update, or any service for a shift quality complaint. It runs with the wheels blocked, brakes applied, zero throttle and fluid at 158-212 degrees F, and the engine must be shut off and restarted to finish.
Will a new TCM fix Equinox shift problems?
Usually not. GM bulletin 09-07-30-012F says not to replace the TEHCM for a DTC unless service diagnostics call for it, and 18-NA-358 says TEHCM replacement has not fixed the 2014-2017 shudder and flare concern. On 2008-2012 Gen 1 units, failed pressure switches can be serviced instead of replacing the whole module.
Related guides
Sources
- General Motors, Service Bulletin 09-07-30-012F, "No Reverse, 3rd or 5th, Check Engine Light Illuminated, DTC P0776" (2008-2009 Equinox, RPO MH2/MH4). Backs the 3rd/5th harsh shift and flare symptoms, P0776 and companion codes, the broken 3-5-R wave plate, updated plate 24254103, the case-split clean-out, the TEHCM caution and the DEXRON VI 88861037 quantity. static.nhtsa.gov (PDF)
- General Motors, Service Bulletin 18-NA-358, "Shudder, 2-3 Upshift or 3-2 Downshift Concern." Backs the 2014-2017 Equinox RPO M7U/M7W listing, shudder with flare, slide, slip or harsh shift, the misfire and TCC slip checks, the 5-second power brake test, valve bodies 24281084 and 24257450, the TEHCM note and the speed sensor debris check. static.nhtsa.gov (PDF)
- GM service information for the 6T70/6T75 (2011 Saab 9-4X workshop manual): Harsh Garage Shift, Harsh or Late Third, Fifth and Reverse Shift, Harsh Fourth, Fifth and Sixth Shift, Transmission Adaptive Values Learn, Road Test and Line Pressure Check. Backs the symptom-table checks by clutch, the 800 kPa idle line pressure limit and engine torque note, the 1-2 second shift timing, the 100 RPM / 6 second TCC slip limit, the 200 kPa line pressure steps and 12 Nm plug torque, and the adaptive learn conditions. Harsh Garage Shift / Harsh 3rd, 5th, Reverse / Harsh 4th, 5th, 6th / Adaptive Values Learn / Road Test
- ATRA, "6T70 Product Issues and Updates" seminar. Backs the 2013 Gen 2 split for M7U/M7W, the hot fluid check at 180-200 degrees F, and the Gen 2 CP Learn gears and rough-road abort. atracom (PDF)
- Sonnax, "The Greatest Generation: How Small Changes Led to the New Form and Function of Gen. 2 6T70/75 Valve Bodies." Backs the Gen 2 valve body changes (no pressure switches, No. 10 checkball, six dampers, revised regulators and accumulator spring, incompatible separator plates) and the Gen 1 valve wear symptoms for the 3-5-R and 2-6 regulators and the 4-5-6 accumulator. sonnax.com
- Sonnax, "6T70/6F50 Webinar." Backs the clutch apply chart and the Gen 1 pressure switch 8/12 psi values and associated codes P0752, P0872, P0877 and P0989. Sonnax (PDF)