I have '92 124 2.5 turbo diesel. The auxilary fan will not come on. Fuse is good, in line fuse is good. It will run if I run 12 volts to it. I grounded the wires running to the high pressure switch and the fan did not come on. The wires feeding that high pressure switch have VERY LOW voltage to them as they made my test light glow but barely! I need this fan to work so my AC pressures will be correct. TIA Ernie