The Chrysler K-Car Club

Last November I bought an 86 Mark cross lebaron and I've been loving it. However I've been having problems with my radiator fan the past few weeks. First I replaced the relay, then I replaced the temp sensor, then the fan motor. I'm really running out of ideas as far as what could be wrong. I tested the voltage back when I was first having trouble and it was showing 8v at the motor connection but now when the relay clicks on the voltage barely jumps. I bought a Haynes manual specifically for this problem but it seems the only part they gloss over about is the fan circuit. Any advice would be greatly appreciated.