R107 380SL automatic - delayed 1-2 shift when cold - is it the shift solenoid or the modulator

Berny.

Cold-only 1-2 shift hang on the 722.3 is almost always the vacuum modulator. The modulator controls line pressure based on engine vacuum. When cold, the rubber diaphragm inside the modulator is stiffer and slower to respond. As temperature rises, the diaphragm warms and responds correctly.

The shift solenoids (B6/B7) are electrical and either work or do not work - they are not temperature-dependent in the way you describe.

Test the modulator:

Disconnect the vacuum line from the modulator. Cold engine.

Apply a hand-held vacuum pump to the modulator port. Should hold 15+ inHg without leakage.

If it does not hold, the modulator diaphragm has perished and the modulator must be replaced.

Replacement modulator is about $95 at MB Sydney Service in 2018. A 10-minute change with the gearbox in the car.