You should be able to find a shop manual at your local library -- make copies of the right sections as they are usually only available in the REFERENCE section...good luck :)
The 2000 Buick Regal cooling fan circuit relay switch can be found in the fuse box. The fuse box is located in the engine compartment.
pull it and switch it with your wiper relay or a similar same part numbered one.
I believe yours has a starter mounted solenoid and not a relay.
fuse relay wiring switch
I had a similar problem w/ a 2000 Regal. The ignition switch has a circuit that is shared with the turn signals (draw up to 9A) and also controls the ignition relay. That circuit had a bad contact in the switch. I work in electronics & I worked @ this for quite a while. Had the ignition switch changed out (about $60 for switch + labor) . You still use the same lock so no change of key is required. Changed out over 3 yrs. ago & no issues since.
On a 1998 Buick Regal LS, the starter relay switch is typically located in the under-hood fuse box. You can find the fuse box on the driver's side, near the front of the engine compartment. The relay itself is usually labeled, and you may need to consult the owner's manual for the exact location and identification of the starter relay within the fuse box.
It could be the ignition switch or a fuse. Maybe a relay.
The 1996 Buick Century horn relay switch is located behind the dashboard. The relay switch will be on the drivers side of the dashboard.
To reset the fuel pump relay switch on a 1994 Buick Skylark, locate the relay in the fuse box under the dashboard or in the engine compartment. Remove the relay and wait a few minutes before reinserting it to reset the system. Additionally, ensure that the ignition is off during this process. If the relay continues to malfunction, it may need to be replaced.
Mounted inside the fuel tank.
On the top of the starter where wires connect
bad relay