Problem 1: Headlight switch occasionally needs to be jiggled to get headlights on. Problem 2: Wipers only work in the “spray and wipe” mode.
My Solution: Removed dash, installed new switches, replaced dash.
Result: Now the right headlight does not come on at all. Wipers STILL only work in the “Spray and wipe” mode.
Question: Where do I go from here?
Both those circuits are controlled by the Body Control Module.
The BCM’s on these vehicles are well known for their failures that RockAuto is even out of stock.
Tester
Right and left headlights are powered by the same relay but have separate fuses. Check for power to the headlight and fuses 22,23,24 and 25 in the PDC (under hood fuse box).
I hope you had a good reason to remove the dash other than replacing two switches.
Well it sounds like you have spent a fair amount of time and money on the troubles without much success. If you plan on keeping this vehicle I suggest you purchase the factory service manual for it. It will really help you understand how things are connected for the wiring and the other mechanical systems of the vehicle. It is money well spent if you want to work on things yourself. Having a test meter is also a good investment.
I agree with @Tester, the wiper trouble is most likely with the BCM module. Using the service manual and meter you could verify that the wiring to the module is okay first before committing to purchasing one.
I assume you have made sure that the right side bulb is still good and isn’t blown out. It sounds like there is a faulty connection causing the trouble.
Does the one working headlight work correctly now and not affected by jiggling of the switch? If so, you had to replace that headlight switch anyway, so removing the dash was probably necessary in any event. For why one headlight works and one doesn’t, I’d start at the bulbs and work backwards towards the switch. Eventually you’ll find where one circuit is working and the other isn’t. The ideas posted above by Nevada are a good place to start.
Agree with @Tester on this (may I say as usual). These cars are well known for bad body control modules.
Allpar.com forums is a great resource and when I had our 2000 Caravan (RIP shorty!), I was on that site very often.
BCM failure is a possibility but I found a break in the wiper multiplex wire between the switch and BCM to be more common. The circuit should be tested.