FCA PROXI Tool logo
Online service Download
EN/UA
+380 93 440 2002WhatsApp / Telegram
Jeep Wagoneer / Grand Wagoneer • write failed

Jeep Wagoneer / Grand Wagoneer “PROXI Alignment Failed” (Write Troubleshooting)

If your scan tool shows “PROXI alignment failed”, “proxy alignment failed”, or the write step is rejected, the cause is usually not the edited bytes themselves. On Wagoneer / Grand Wagoneer the most common blockers are SGW/session authorization, unstable power, adapter/bus issues, or writing to the wrong ECU. This guide gives a practical checklist and explains how FCA PROXI Tool fits: keep the original Configuration Code, generate checksum-correct output, and write only to the ECU(s) that need the change.

Most common

Why writes fail on late platforms

  • Access / SGW: your session is not authorized for writes.
  • Power: voltage dips during write or ignition state changes.
  • Adapter / bus: wrong interface mode, unstable link, wrong bus path.
  • Wrong target ECU: writing to a module that doesn’t own the byte you changed.
  • Bad source buffer: edited from a mismatched file or corrupted export.
Data integrity

Where FCA PROXI Tool helps

FCA PROXI Tool focuses on the configuration itself:
  • Keep the original Configuration Code (sync identity).
  • Change only the needed bytes/bits.
  • Generate checksum-correct output (proprietary CRC/checksum logic).
  • Write only to the ECU(s) that need the change, then validate.
If you still get a “failed” result, the cause is usually access/session or targeting, not the checksum math.
Don’t guess

Reduce the change set

If you changed many flags at once, roll back to a minimal edit and re-test. A smaller diff makes it easier to identify whether the failure is access-related or a specific byte triggers rejection.
Safety

Protect the vehicle

Always keep an untouched backup of the original buffer. If a write is interrupted, restore the original data first before attempting other procedures.

Quick navigation

Typical messages (what people search for)

Different tools call the same situation by different names. Treat them as “write rejected / not authorized / not accepted” until proven otherwise.

Keyword

“PROXI alignment failed” / “proxy alignment failed”

Usually means the workflow couldn’t complete a final sync step or the write request was rejected. On WL, access/authorization and correct targeting are frequent causes.
Keyword

“Security access required” / “Request out of range”

Common when SGW/session requirements aren’t satisfied, or the ECU refuses a request in the current ignition state.
Keyword

Write completes but nothing changes

Often a targeting issue: you wrote the right file to the wrong module, or the module you wrote does not own the specific option byte you edited.

Checklist: fix the failure in the right order

Don’t jump straight to “full alignment”. Most failures are basic: access, power, interface, target selection.

  1. Stabilize power: charger/power supply, stable ignition state, no sleep events.
  2. Confirm access: if WL requires authorized write access, use a supported/authorized session.
  3. Validate your source: start from the correct exported WL buffer and keep an untouched backup.
  4. Keep Configuration Code: do not replace the vehicle identity unless your use-case demands it.
  5. Minimize the diff: change only the option you need, then re-test.
  6. Write to the right ECU(s): target the module(s) that actually store/apply the changed option.
  7. Re-check after write: read back or verify behavior/DTCs immediately.

When a full alignment routine may still be needed

If you preserve the original Configuration Code and your output is checksum-correct, a separate alignment routine is often unnecessary. It becomes relevant mainly in edge cases.

Identity mismatch

Different Configuration Code is already present

If the car is already in a mismatch state because the accepted identity changed (module swap / wrong buffer), you may need an OEM synchronization routine after restoring a single consistent configuration.
Major swap

BCM / cluster replaced with different identity

Replacing key identity-holding modules can require a guided sync step to unify the network. Fix the configuration source first, then sync only if the vehicle still insists.
Already in mismatch

Vehicle already reports mismatch DTCs

Don’t blame your latest edit automatically. Confirm the baseline is consistent, then re-apply your minimal changes.

FAQ

Is a “write failed” result always a bad file?

No. On Wagoneer / Grand Wagoneer, access/session authorization and interface stability are common failure points. If FCA PROXI Tool produced checksum-correct output and you kept the original Configuration Code, investigate SGW/access and targeting first.

Can FCA PROXI Tool bypass SGW?

No. FCA PROXI Tool prepares configuration edits and generates checksum-correct output. If SGW blocks the write session, you need an authorized diagnostic workflow for that vehicle.

Do I have to write the edited file to every ECU?

Usually not. In typical retrofit/conversion work you can write only to the ECU(s) that require the change. Keeping the original Configuration Code helps the network stay consistent after targeted writes.