Most Grand Cherokee eight-speed shift complaints that come through the door are not broken parts. A bump on the 2-1 coming to a stop, a lazy 1-2 on a cold morning, a hunt between 1st and 2nd in Selec-Speed, an ECO button that turns itself back on: FCA has written a TCM software bulletin for every one of those. The ones that are hardware usually show it in the adaptation data before they show it on the road test, so the scan tool decides whether this is a flash, a relearn or a valve body.
This post covers the 2014-up WK2 and the 2021-up WL, and it stays on shift quality: harsh, late, bumpy, hunting or flaring shifts. Slipping and lost gears have their own guide, ZF8HP Jeep Grand Cherokee slipping: causes and fix, and the full fault list is in our Grand Cherokee common problems guide.
Start With the Sales Code and the Build Date
Every FCA shift bulletin for this Jeep is gated by engine sales code, transmission sales code and build date, so get all three before you road test. The V6 WK2 runs the 845RE (sales code DFL), the Hemi, 3.0L EcoDiesel and 6.4L SRT run the 8HP70 (DFD or DFK), and the WL runs the second-generation 850RE (DFT). The table lists the shift-quality bulletins we pulled from NHTSA's server, with the complaints FCA wrote down.
| Bulletin | Applies to | Shift complaints it fixes |
|---|---|---|
| 21-039-14 (Nov 2014) | 2015 WK, 3.0L gas EHD and 3.6L ERB with 845RE DFL, 5.7L EZH with 8HP70; built roughly July 21 to October 17, 2014 | V6: 4-3 and 3-2 downshifts, high-altitude and sand-mode shift timing, multi-gear passing downshifts, intermittent delayed upshift. Hemi: upshift timing in eco, base and hill modes and on cruise, 8-7, 3-2 and 2-1 downshift timing, converter engagement |
| 21-003-15 (Jan 2015) | 2014 WK with 5.7L EZH and 8HP70 DFD | ECO mode not retained after a key cycle, light-throttle upshift quality, power-on (passing) downshifts, tip-in/out with the converter clutch applied, engagement in 4x4 High and Low |
| 21-045-15 (Jul 2015) | 2015 WK, 3.0L diesel EXF with 8HP70, built on or before June 18, 2015 | Low-speed tip-in bump, coast-down flare at altitude, 6-5 and 1-2 bumps, delayed upshifts in 1st or 2nd, 4WD Low shift quality, Snow mode paddle 2-1 |
| 21-018-15 (Mar 2015) | 2015 WK SRT, 6.4L ESG with 8HP70, built on or before March 3, 2015 | Erratic cold 1-2, delayed reverse-to-drive engagement, intermittent harsh upshifts and coast or passing downshifts, delayed shift out of 6th at high speed |
| 21-002-17 Rev. A (Jun 2017) | 2017 WK SRT, 6.4L ESG with 8HP70 DFK, built on or before May 17, 2017 | 2-1 and 6-5 bumps while braking, 5-4 downshift, P1DCD-00, fixed-gear limp mode |
| 21-015-23 (Jun 2023) | 2022 WL with 850RE DFT | Excessive 1-2 shifting in Selec-Speed Control; FCA lists the cause as TCM software |
If the VIN and the complaint both match a row, the fix is on the bulletin and a teardown is premature. If the Jeep already has the latest calibration and the complaint is still there, move on to adaptation.
Tie the Bad Shift to the Clutches That Change
The eight-speed uses four planetary sets, two brakes (A and B) and three clutches (C, D and E), and per Sonnax's apply chart each gear holds exactly three of the five. A single-step shift releases one element and applies another, so every complaint has two suspects. FCA's own example in bulletin 21-012-14 Rev. B is the 2-1 downshift: A and B stay on, E releases and C applies, so a bad 2-1 is a C or E problem and nothing else.
The same bulletin lists which shift each element learns on, which is the most useful table in the Jeep's service information for this complaint:
| Element | Adapts on | Best learned |
|---|---|---|
| A | 6-7 | Highway, above 50 mph |
| B | 6-5 coast | Throttle at 0%, no brake |
| C | 2-3 and 4-5 | Light to medium throttle launch |
| D | 3-4 | Light to medium throttle launch |
| E | 1-2 and 5-6 | Light to medium throttle launch |
Write the road test down shift by shift. A Jeep that bumps on 2-1 and 6-5 while braking is the exact pattern in the SRT bulletin. A Jeep whose 1-2 and 5-6 are both firm points at E. A harsh 6-5 coast-down with everything else fine points at B, which only learns when the driver coasts off the throttle, something a lot of owners never do.
Check 1: Codes and Fluid Level
Pull TCM codes before anything else. FCA's bulletins all start by telling the tech to repair any stored DTC first, and a solenoid, speed sensor or voltage code changes the diagnosis. Then confirm the level. These Jeeps have no dipstick; ZF Service Information 50130 sets the level at the fill plug with the oil at 30-50 C after cycling P, R and D. Low oil makes shifts late and flared under load, while an overfill can aerate and give soft, inconsistent applies. The full procedure, with plug torques and capacities, is in our ZF8HP fluid type and capacity guide.
Check 2: Software, Done Right
Every bulletin in the table is a TCM reflash, and every one carries the same warning: hook up a battery charger so voltage stays above 13.2 volts and does not climb above 13.5 volts during the flash, and restart the flash if it aborts. A flash done on a sagging battery is how a Jeep with a shift complaint becomes a Jeep with a no-start or a dead TCM.
Pay attention to what each bulletin says about adaptives, because they disagree. Bulletin 21-039-14 says in capitals not to clear the shift adaptives after the flash, because the transmission may not shift smoothly until they relearn; it pays 0.2 hours. Bulletin 21-002-17 Rev. A for the 2017 SRT does the opposite: reset the adaptive values and run the Quick Learn routine under Misc Functions, and it pays 0.5 hours for the flash plus Quick Learn. Follow the bulletin that matches the VIN, not habit. The WL bulletin 21-015-23 is a plain 0.2-hour reprogram.
Check 3: Read the Adaptation Cells
If the software is current and the shift is still poor, the adaptation data is the next stop. Bulletin 21-012-14 Rev. B explains that the TCM records, for every element, how long it takes to fill (Fast Filling Counter and Filling Time, in milliseconds from zero) and how much pressure it needs (Filling Counter and Filling Pressure, in millibar or psi from zero). The cells start at zero on a new transmission, a replaced TCM or after a reset with the scan tool, and shift quality may not meet expectations until they learn.
What to look for on the scan tool:
- Counters near zero. The cell has not learned. FCA wants the Filling Counter at 12 or more and the Fast Filling Counter at 4 or more on the 845RE, and 6 and 2 on the 8HP70. A Jeep that just had a battery, TCM or transmission job and shifts badly with low counters needs the drive learn, not parts.
- High counters and offsets still moving. An element that has hundreds of learn events and keeps adding fill time is compensating for something: a leaking circuit, a worn valve bore, a sticking accumulator or a pack with too much clearance. That is a hardware lead, and it tells you which element to chase.
- One element far from the others. Compare the five. If C, D and E all sit within a few milliseconds and E is way out, the problem lives on E's circuit.
The 845RE carries one extra step. FCA requires 2014-2015 DFL Jeeps to complete the 845RE Quick Learn (bulletin 21-030-14 or later) and be re-evaluated before running the drive learn.
The FCA drive learn, in numbers
FCA rates each upshift and each downshift with light braking, plus the neutral-to-reverse engagement, from 1 to 10, with the oil at least 30 C. Any shift under 5 gets the adaptation drive learn. The learn is sensitive to temperature, input torque and turbine speed, and these are the numbers from the bulletin:
- Upshifts: oil 30-100 C (50-100 C for the targeted procedure), engine torque 100-150 Nm (74-111 lb-ft) on the scan tool, turbine speed 1,250-2,000 rpm, accelerating from a stop to 40-50 mph.
- B element on the 6-5 coast: throttle at 0%, no brake until the shift completes, input torque between -60 and -40 Nm, input speed 750-1,100 rpm.
- Learning aborts above 100 C oil temperature.
- Use a smooth, flat road with no lights or stop signs. Tar strips and potholes upset the torque signal and delay the learn, and rolling hills can drop torque too low to record.
For a single bad shift, the targeted procedure holds the Jeep in a steady gear with the paddles: A in 6th and B in 7th at 45-50 mph, C in 4th and D in 3rd at 20-35 mph, E in 7th at 45-50 mph, all at 950-1,750 rpm input speed. FCA's labor times are 0.5 hours to rate the shifts, 1.4 hours for the full learn after a repair, and 1.9 hours for a two-element targeted learn. Tell the owner the shifts keep improving as miles add up, because the bulletin says the adaptation keeps updating.
Check 4: When It Is Hardware
Once codes, level, software and adaptation are cleared, the mechatronic is the usual hardware suspect. Sonnax's breakdown of the ZF8 valve body shows eight EDS solenoids on the lower casting and rubber-tipped solenoid accumulators in the upper casting for the TCC, EPC and each clutch and brake circuit. The plastic TCM assembly on top also carries the input and output speed sensors and the oil temperature sensor, so a speed signal dropout looks like a shift problem until you graph it. A worn accumulator or a solenoid that has lost its curve makes one element apply late or hard, which is what an adaptation cell that keeps running away is telling you.
A firm shift into or out of 1st, 2nd and reverse, with reverse getting softer over time, fits the A brake. Sonnax documents the weak OE A backing plate flexing during apply, which causes uneven wear and heat in that pack, and sells heavy-duty plates for the 8HP45/845RE/850RE (35577-45) and the 8HP70 (35577-70). That is a rebuild, not a valve body swap. After any valve body, mechatronic or internal repair, FCA says to clear the adaptation cells (unless the mechatronic itself was replaced, which arrives at zero) and run the full drive learn.
Make Sure It Is Not the Shifter
Some "shift problems" on a 2014-2015 WK are the electronic monostable gear selector, not the transmission. The lever returns to center after every selection, and FCA's Part 573 report for recall 16V-240 (FCA S27) says drivers were wrongly concluding the vehicle was in Park and getting out with the engine running. The recall covered 811,586 vehicles, including Grand Cherokees built July 16, 2012 to December 22, 2015, and the remedy was software adding another layer of protection against leaving the selector out of Park. Run the VIN for open recalls before you chase a "won't stay in Park" or "went into neutral" complaint inside the transmission.
Keeping the Shifts Clean
- Set the level only in the 30-50 C window, with ZF LifeguardFluid 8 or an approved equivalent. ZF warns against additives in this unit.
- Put a charger on the battery for every flash, and check the TCM calibration level on any Jeep that comes in with a shift complaint.
- After a battery disconnect, TCM work or a repair, either drive the learn routine or tell the owner what to expect for the first few hundred miles.
- Do not clear adaptives as a first move. On a Jeep that has learned around wear, a reset can make the shifts worse until the learn completes, which is exactly why 21-039-14 warns against it.
Shop the part for this fix
When the adaptation data points at a solenoid on a 2014-2017 Hemi, EcoDiesel or SRT Grand Cherokee, Core Transmission Parts carries an 8HP70 shift solenoid kit for those years. Check DFD or DFK on the build sheet first, since V6 Jeeps run the 845RE.
See the 8HP70 shift solenoid kit at Core Transmission Parts →Frequently Asked Questions
Why does my Jeep Grand Cherokee 8-speed shift hard?
On most 2014-2017 WK2s the first suspect is TCM calibration. FCA released reflash bulletins 21-039-14, 21-003-15, 21-018-15, 21-045-15 and 21-002-17 for harsh, bumpy or delayed shifts, gated by engine, transmission sales code and build date. If the software is current, check the fluid level and the adaptation cells before replacing parts.
How do I reset the transmission adaptation on a Grand Cherokee?
Adaptation memory cells are cleared with the scan tool, and FCA bulletin 21-012-14 Rev. B then requires a drive learn: oil at 30-100 C, 100-150 Nm engine torque and 1,250-2,000 rpm turbine speed while accelerating to 40-50 mph, plus a 6-5 coast-down with no brake for the B element. Do not clear the cells as a first move, because the shifts can get worse until they relearn.
Is there a TSB for Grand Cherokee 2-1 downshift bump?
Yes. Bulletin 21-039-14 covers 2-1 and 3-2 downshift timing on 2015 WKs, and 21-002-17 Rev. A covers 2-1 and 6-5 bumps while braking on 2017 SRT models with the 6.4L and 8HP70. Both are TCM reflashes, and the SRT bulletin adds an adaptive reset and Quick Learn.
Why does my 2022 Grand Cherokee keep shifting between 1st and 2nd?
FCA bulletin 21-015-23 covers 2022 WL Grand Cherokees with the 850RE (DFT) that shift excessively between 1st and 2nd in Selec-Speed Control. FCA lists TCM software as the cause, and the repair is a 0.2-hour reprogram.
Sources
- FCA US LLC (Chrysler Group LLC), Service Bulletin 21-012-14 Rev. B, "8 Speed Transmission Shift Adaptation, Drive Learn Procedure" (September 26, 2014), on NHTSA's bulletin server. Backs the adaptation memory cell definitions, the reset conditions, the 12/4 (845RE) and 6/2 (8HP70) counter targets, the 1-10 rating with the under-5 threshold, the 845RE Quick Learn prerequisite (21-030-14), the 2-1 example, the clutch-versus-shift table, the temperature, torque and speed windows, the steady-gear table and the 0.5, 1.4 and 1.9 hour labor times. static.nhtsa.gov (PDF)
- FCA US LLC, Service Bulletins 21-039-14 (November 25, 2014), 21-003-15 (January 24, 2015) and 21-045-15 (July 3, 2015), "Flash: Transmission Shift Enhancements", on NHTSA's bulletin server. Back the 2014-2015 WK sales codes and build windows, the per-engine V6, Hemi and EcoDiesel shift complaints, ECO mode not retaining, the 13.2-13.5 V charger rule, the instruction not to clear shift adaptives and the 0.2 hour labor time. 21-039-14 (PDF), 21-003-15 (PDF) and 21-045-15 (PDF)
- FCA US LLC, Service Bulletins 21-018-15 (March 25, 2015), 21-002-17 Rev. A (June 9, 2017) and 21-015-23 (June 23, 2023), on NHTSA's bulletin server. Back the SRT 6.4L (ESG) cold 1-2, delayed R-D and harsh shift complaints, the 2-1 and 6-5 braking bumps, P1DCD-00, the adaptive reset and Quick Learn step with its 0.5 hour time, and the 2022 WL 850RE 1-2 hunting in Selec-Speed Control with TCM software as the cause. 21-018-15 (PDF), 21-002-17 Rev. A (PDF) and 21-015-23 (PDF)
- FCA US LLC, Part 573 Safety Recall Report 16V-240 (FCA recall S27), submitted May 24, 2016, on NHTSA's recall server. Backs the 2014-2015 WK monostable shifter coverage, the July 16, 2012 to December 22, 2015 production window, the 811,586-vehicle population, the defect description and the software remedy. static.nhtsa.gov (PDF)
- ZF Friedrichshafen AG, Service Information 50130 EN, "Oil change kit for ZF 8HP automatic transmission," and the ZF LifeguardFluid 8 Product Data Sheet. Back the fill-plug level check at 30-50 C after the P-R-D cycle, the overfill and underfill warnings and the no-additives rule. SI 50130 (PDF) and LifeguardFluid 8 data sheet (PDF)
- Sonnax, "A New Path for ZF" and "How to Prevent ZF8, 845RE, 850RE A Clutch Failure." Back the two brakes and three clutches with three elements per gear, the eight EDS solenoids, the rubber-tipped solenoid accumulators, the TCM assembly housing the speed and temperature sensors, the flexing OE A backing plate and the 35577-45 and 35577-70 heavy-duty plates. A New Path for ZF and A clutch failure
Shop solenoid kits, valve bodies, pan and filter service kits and ZF fluid for the Grand Cherokee 845RE and 8HP70, on our own secure checkout.
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