ACD pump faults: all ACD mode lights flash
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What causes "ACD pump faults: all ACD mode lights flash" on the Mitsubishi Lancer Evolution IX (2006), and how is it fixed?
Owners trace it to corrosion on the ACD pump's contacts or plate, a failed pump, or a blown fuse or bad relay feeding the pump. Fix: Check the ACD fuse and relay first, then the pump and its connections; clean corrosion or replace the pump.
Symptoms
The ACD indicator lights flash together and the center differential stops working; owners report a stored ACD fault code.
Cause
Owners trace it to corrosion on the ACD pump's contacts or plate, a failed pump, or a blown fuse or bad relay feeding the pump.
Fix (summary)
Check the ACD fuse and relay first, then the pump and its connections; clean corrosion or replace the pump. Forum-only.
Other CT9A (Evolution IX) problems
- Recall 16V-334: passenger front air bag inflator may rupture (2006)
- Recall 16V-458: front crossmember corrosion can let the lower arms detach (salt states)
- Rear wing center element can break at high speed
More for this car
- All Mitsubishi Lancer Evolution IX (2006) fitment answers · CT9A (Evolution IX) common problems
- Newsletter archive: past issues with every new and corrected entry
Sources
- ACD Pump Issue Solved — EvolutionM forum (forum thread; read 2026-10-26; full page read)'06 MR: all ACD lights once warm; pump plate corrosion most common; relay and fuse also.
- Need Help Troubleshooting failed evo 9 ACD pump — EvolutionM forum (forum thread; read 2026-10-26; full page read)Pump not running; check the fuse at the battery and the relay.
- Mitsubishi Lancer Evolution - What's New for 2005 — Mitsubishi Motors North America (mfr spec; read 2026-10-26; full page read)ACD on all 2005 Evolutions.
Summaries are in our own words. Not repair instructions; consult the factory service manual.
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