A/T - A4LD No Or Late Upshift after New Modulator

TSB 86-57 (Nov)

SUBJECT: FORD A4LD

PROBLEM:
No upshift, or very late upshift, after installing a new vacuum modulator

POSSIBLE CAUSES:
When installing a new vacuum modulator, on an A4LD transmission, be certain you're not using a C-3 vacuum modulator.




The only visible difference between the C-3 vacuum modulator is on the transmission end of the stem. The A4LD modulator is recessed to allow the modulator valve to move toward the vacuum modulator.

If a C-3 vacuum modulator is installed on an A4LD transmission, the modulator valve is blocked to the bottom of its bore. The resulting problem is -- no upshift, or very late upshift.