The codes are... P1684 (PCM MEMORY LOST
), P1491 (RADIATOR FAN RELAY CIRCUIT
) and P0645 (A/C CLUTCH RELAY CIRCUIT
). It looks like you're right about the fans.. I misinterpreted what was happening.
P1684 describes a loss of engine controller memory that would have happened within the last 255 engine starts. This could be something as innocuous as a dead or disconnected battery.
P1491 usually means a fuse is blown in the underhood fuse and relay box, the PDC. Look for the 40 amp "maxi" fuse that your under-cover road map identifes as the fan relay and check it carefully for being burned out. They're not always obvious about showing signs of failure, so it might require that you remove the clear plastic top on the fuse or test it physically with an ohmmeter. If the fuse is found to be blown, check each of the fan units to see if there might be binding of a motor, which is what usually pops a fuse. Fans are serviced as a set, coming with an entire fan "module" (about $450) by the way. You could unplug the bad one to limp the van along a while on the single good fan.
P0645 tells us that the control circuit feed to the A/C clutch relay isn't (or wasn't) present.
Clocksprings are best purchased as new since they have such an important role in driver's side airbag deployment, which is yet another function of the unit. Since the airbag sits in an environment that isn't stationary, the clockspring was created to maintain electrical contact with the unit at all times. Inside, it looks just like what you'd expect a device called a clock spring to appear... it's a wound ribbon of multiple conductor material that spools and spools with each turn of the steering wheel, which is why they tend to break after a while. You can only wind a spring so
many times before it snaps. I checked your model year Caravan for the possibility of a recall clock spring being available, but no bingo.
While you don't always lose all functions at the same time when a clock spring fails, it may well complete that process any day now if this is what's going on. Testing of the horn and speed control circuits will be difficult without the use of a scan tool that can read the MUX voltage needed for setting speed control.
The clock spring makes physical contact with the base mounting surface of your steering wheel, which means it sits inside the column shroud just a bit. It appears to be a black plastic hub of some sort with a tab at the center (facing the wheel once removed). Care must be used when attempting to re-use a clock spring to keep it from unwinding once removed from the column or you'll have the thing winding up too tight on one turn and too loose on the other.
The dome lamp and A/C relay control circuit problems might just be a bad fuse, such as the ignition-off draw (called IOD) located in the PDC unit. I believe it to be a 20 amp mini fuse in this year.
Check 'em out and let me know what you find.