Your success with solving the high idle complaint will come easier with a good plan of attack. The first thing to determine is whether the high idle is caused by a mechanical issue, such as a faulty IAC, or a throttle plate that is not closing, or if the idle speed is actually being commanded high by the computer. One of the easiest ways to do that is to simply unplug the IAC with the truck at idle, and allow the engine to slow to the "minimum air rate" or base idle speed. There is no published spec, but if your minimum idle speed is in the 500-600rpm range in park, thats close enough. There is no normal service adjustments required, but if something is keeping the throttle plate from closing, then you'll have to correct that. Most likely, when you unplug the IAC, you will find either a normal minimum idle, or no change at all. If there is no change, and the throttle is not sticking open, suspect air is getting around the throttle plate, which could be a bad IAC, because thats exactly what it does, it allows air to enter the engine around the throttle plate. Normally the computer has complete control of the IAC, but it can fail mechanically, so it must be checked. The last senario has the idle speed being correct when the IAC is unplugged, and then going back up when it's plugged back in. this would suggest the computer is actually commanding the idle speed high. The questions from here are, is the computer getting a high power steering pressure input? Is the TPS spiking low, causing the computer to think the engine is at part throttle? Is the ECT, or IAT reporting to low of an engine temperature? This is where the correct scan tool becomes so important, because it allows the person trying to fix the car to see this information right from the computer.

The A/C relay on your Honda, like most vehicles today, is computer controlled. The relay will have electrical power at two terminals of the relay with the key on and power at only one terminal with the key off. If there is no electrical power present at the relay, then you have to inspect the fuses. There are two fuses for the relay. One can be found in the under dash fuse panel. It will be a 7.5 amp fuse and will be located in position #6 of the fuse panel labeled A/C clutch relay/cooling fan relay. The other fuse is located in the under hood relay and fuse box. This is a 15 amp fuse and will be in position # 34 and labeled condenser/fan. If both fuses are good and there is electrical power to two of the terminals at the A/C compressor clutch relay, then you have a control problem. It could be as simple as a bad relay or the A/C system is low in charge. The A/C system has a pressure switch that stops the operation of the A/C compressor if the charge of refrigerant in the system becomes inadequate, too low. This is done to prevent damage to the compressor. To diagnose a control problem will require more specialized equipment, higher level of training and knowledge for diagnosis. At this point I would suggest that you involve a repair facility to perform this diagnosis.

Until proven otherwise, approach each failure as if they are occurring on different cars. The biggest mistake people make when attempting diagnostics is assuming things are related, they can be, but certainly don't have to be. So pick one, and troubleshoot it, then move onto another. If you happen to solve more than one with a particular repair, simply smile and move on. The headlights, tail-lights. They share a common power input to the headlight switch on most vehicles, but not all. Start with a schematic and check to see how the power distribution feeds power to the switch assembly. Question, do you have high beams when you pull the dimmer handle for "flash to pass"? No Bus. That means the serial data bust has shut down on the car. Unfortunately, that will be a failure that is likely beyond your ability to diagnose. You need the Chrysler DRBIII scan tool and its strength as the factory tool, plus a digital storage oscilloscope to diagnose that problem efficiently. The locks locking/unlocking by themselves could be a result of the failing data bus, or simply a bad door switch, with the previous being more likely at the moment. When the BCM sees serial data report that the vehicle is moving it locks the doors. Once it sees that the vehicle has been stopped and shifted to park, it unlocks the doors. The loss of serial data could cause this to occur incorrectly. The fact that it occurs after its been raining could indeed be a clue. We often find modules damaged by water intrusion on many different vehicles. Sometimes things like a windshield seal are to blame. One vehicle I can think of off hand has a TSB where the technician has to install a set of shields to protect a new computer from rainwater when its replaced. (Not a Chrysler vehicle that comes to mind, this is just a reference) You really do need a pro to sort this out. One that understands electronics, and has the correct equipment to communicate with your cars computers.

It could be something as simple as a ground wire left disconnected or supply wire left disconnected. If you want to find the fuse or possibly a breaker, look at the wiring diagrams in the repair manual for identifying details. If you are lucky, the various connectors ID designators and wire colors can be found. You are not done once you find the terminal number. Next, you'll need to search the manual to find the location of that termination. You'll probably need an official repair manual. Low cost, third party manuals are often skimpy on these diagrams. These days, the dealer may not have repair manuals. Several service shops in my area have terminals in the repair bay for accessing repair information on-line from a corporate server. If your lighting outage happened immediately after the shop worked on it, very likely they have a good idea where the problem is (if it is a disconnection done while working on the system). The shop should be willing to correct the problem at no charge if it was an oversight on their part. However, if upon opening the system, it is found that the problem was not due to an oversight, expect to pay for the repair. Take the vehicle back to the shop and discuss.