A/T - A4LD No Upshift/Restricted Modulator

TSB 88-17 (Apr)

SUBJECT: FORD A 4LD

PROBLEM: No upshift

CAUSE: Restricted modulator

Some Ford A4LD modulators have been the reason for a "no upshift" condition. When vacuum is applied to the modulator, it will hold vacuum, and it appears the diaphragm is working properly.

CHECK:




The best way to check a Ford A4LD modulator is to remove it from the transmission. Connect a vacuum pump to the inlet on the modulator, install the pin, and pump vacuum to 17 inches. Be sure the pin drops. If the pin does not drop, check for a restricted orifice at the vacuum inlet tube.