My 91 Volvo is experiencing major electrical problems. The battery is not charging and something is draining the power. I started the car, took out the negative and the engine keeps running. So, I think the alternator is not the problem. The car starts fine when the battery is fully charged or if I jump it. While driving today, the speedometer stopped working, the gas gauge went to empty, the horn stopped working and the car started losing power. After the car had stopped for about 40 minutes, I jumped it and it started without a problem. While driving it back home, the "SRS" on the dash came on. Now if I turn the key to the "ON" position (the car is not moving), the speedometer would go to 60 MPH and would keep getting higher. The odometer was also turning. Could a bad headlight Relay and a bad cooling fan w/ AC relay cause this type of electrical problem? Any ideas what's going on? Thank you.

 

first, I'd never disconnect the battery and try and run the car, the alternator NEEDS the battery in the circuit to act as a power sink.

second, I'd check the battery voltage before starting and while the car is running, the running voltage should be like 1.2-1.4 volts higher than the off voltage if the alternator is charging teh battery. a fully charged battery should read like 12.6V or so at room temperatures, and with the engine running and the battery charged, around 13.9V

now, your other problems with the dash board stuff, that sounds to me like a funky ground somewhere. the speedo and odometer gets pulses from a magnetic pickup on a tone ring in the differential, measuring rear wheel speed. unless the cooling fan comes on spontaneously, I doubt its the ac relay, and if the headlights don't come on spontaneous, ditto the headlight relay.