1) SWM / column controls offline → no turn signals, wipers stuck in one speed, washer inop, DIM buttons dead
Those three CEM codes you saw earlier, CEM-DD41/DD50/DD51 “Communication with Steering Wheel Module (SWM) – signal missing”, are the smoking gun. When the SWM/clockspring is offline, the CEM never “sees” stalk/button inputs, so:
- turn signals don’t work (but hazards can still work because they’re a separate CEM input),
- wipers fall back to a default/limp mode speed,
- washer doesn’t trigger,
- DIM menu/steering-wheel buttons don’t respond.
That points to one of:
• no power/ground to the SWM,
• a broken/shorted LIN wire between SWM ↔︎ CEM,
• a failed SWM/clockspring assembly, or
• corrosion at the CEM connectors (very common on P2 cars, especially ones that have sat or had water in the cowl).
Quick tests
- Do hazards work? If yes, bulbs/CEM outputs are fine and the problem is upstream (SWM input path).
- In VIDA: Network/Diagnostics → see if SWM appears online and read live data from the stalks. If VIDA can’t talk to SWM at all, chase power/ground/LIN first.
- Battery/charging sanity check (these cars get weird below ~12.2 V): ≥12.5 V KOEO, ~13.8–14.4 V running.
Checks in order (10–60 min each):
- Fuses at the CEM related to steering wheel controls/wipers/washer (pull and visually inspect; don’t just meter in place).
- Steering column: disconnect battery and wait 10 min (SRS!), drop the lower column shroud, unplug/reseat the SWM/clockspring connectors, look for green crust/mouse damage right there and along the column tilt area (wires can break where the column moves).
- LIN line quick read at the SWM connector with a DMM (KOEO): you should see ~10–12 V that “wiggles” (averages near battery). If it’s stuck at 0 V (short to ground) or a rock-solid battery voltage (open/short to B+), trace/repair the single-wire LIN back to the CEM.
- CEM corrosion: pull the CEM down (driver’s footwell), unplug the big connectors and inspect for water ingress/green pins. Clean/dry, DeoxIT if needed, reseat firmly. Also make sure the cowl drains aren’t clogged.
- If power/ground and LIN are good, the SWM/clockspring itself is likely failed. Replace as a unit, then do SAS/SWM calibration in VIDA (DSTC calibration). Don’t spin the new clockspring off center.
2) UEM / roof LIN complaints + sunroof inop
- UEM-0004 (siren comm) + UEM-0005 (skylight/sunroof comm) are on the roof LIN. A dead/leaking alarm siren module often kills that bus and can drag the UEM down. Quick isolation: unplug th siren (RF wheel-well) and see if the sunroof comes back after a reset (key on, hold the switch in the closed position for ~10 s). If it does, replace the siren module. If not, check the sunroof motor connector in the headliner and the A-pillar harness for rodent damage.
Other codes (not your primary symptom drivers):
- BCM-0133: brake pressure sensor 2 on the master cylinder. Common. Verify connector/wiring; sensor often needs replacement and a zero-point/calibration in VIDA.
- CEM-1A59 (AUM comm loss): usually an aftermarket radio. Ignore unless you’re chasing audio.
- DIM-0001 (mileage incorrect value): benign; happens with power interruptions. Clear and ignore.
That coolant level sensor unplug while powered: not related to the above. Worst case it set a coolant level DTC.
If it were my car, I’d: (1) confirm hazards work, (2) VIDA-check SWM presence, (3) reseat SWM connectors and inspect the column harness, (4) inspect/clean the CEM connectors, (5) measure the SWM LIN line, and if that all checks out, (6) swap the SWM/clockspring and calibrate. In parallel, unplug the siren to see if the sunroof/UEM faults clear after a sunroof reset.
That sequence usually restores turn signals/wipers/washer/DIM controls on P2 cars with your exact symptom set.