Uploaded May 2014 | Updated September 2026, 1 day ago

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Showing the transmission modulator pressure on my 1991 350SDL. The specification is 55 PSI @ 31 mph in drive. At cold idle the pressure is 1-2 psi less than at the specified measurement speed.

In the 2nd section I operate the modulator with my hand vacuum pump to show the relationship between vacuum and modulator pressure.