85 Silverado Wiring issues

[samseye]

I just bought an 85 Silverado short bed.  307, dual tank and loaded.  I have a couple of electrical issues I could use some help on.

1) The A/C Heater fan.  I can jump the fan from the battery and get full rotation.  However, when hooked up correctly I get a very mild turn.  I checked the Purple lead into the fan and get just over 12 Volts.  I check the lead going into the relay and got a little over 12 on Red line, a little under 12 on the blue and about .2 on the orange.  They read the same regardless of what position I have the fan switch on.  So is my switch shot or should I be looking for something else.

2)  My fuel guage is over the full mark and stays there.  I checked the ground on the drivers side tank and cleaned it up and no movement.  I checked the passenger side and it looked intact, but it was a little difficult to get to.  From what I could tell the fuel tank line switcher is ground in the same spot as the right tank.  So I figure the ground must be fine.  Regardless of which tank I select the guage stays in the same spot and I can here and know the tank line is switching.  (I ran it out of gas on the right side.)  So I figure the ground must be good and it is unlikely it is the sending unit since the guage stays in the same spot regardless of what tank I select.  Any advice as to what to check now?

3) When I turn the ignition key to on or go to crank the starter the wiper goes up and down.  Should I start with replacing the lever or somewhere else?

Thanks in advance for any help!
David

[toplessblazer]

1)Try changing out that little 4 pronged thing ( I think it is a resistor of some kind) on top of the heater box under the hood. It is over by where the hoses go into the heater core.
My 89 sub had this but not sure if your 85 does.  

[123 pugsy]

3) I believe 1 wire to the wipers should have power when the key is off. I think this wire is getting power only when you turn on the key.  

[DnStClr]

On the gas gauge problem, it sounds like you have a bad gauge or else it's not making full contact in the instrument cluster housing.

Don St.Clair
Culleoka Tn

[123 pugsy]

3) Whoops,thinking about something else. Check at the wiper motor if the 2 wires black/blue and grey are shorting out together.