Symptoms:

  • Delayed Reverse
  • Burnt Reverse band
  • Direct clutch burned
  • No Reverse

Cause:

Debris and constant oscillation of the outer Reverse modulator valve can create scratches or wear on the critical valve spools.

Correction:

Restore hydraulic function of the outer reverse modulator valve by installing direct-replacement, Sonnax drop-in valve with or without the related Sonnax sleeve, depending upon original failure mode.
  • 4R44E, 4R55E, 5R44E, 5R55E Outer Reverse Modulator Valve 37947-52
  • 4R44E, 4R55E, 5R44E, 5R55E Outer Reverse Modulator Valve 37947-52

You need this if...

Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if a visual inspection of critical valve spools finds excessive scratches.

4R44E, 4R55E, 5R44E, 5R55E Outer Reverse Modulator Valve Vacuum Test Locations