[Richard L]

This is interesting, Those voltages are too low to turn the transistor on. It should be in the region of 5-7 volts. We have some how lost some voltage somewhere on the "TST" link.

There are three possibilities this voltage can be interfered with, I can rule out two of them by:

1. Removing the gauge harness
2. Removing the Pump harness.

Please now measure location 3...