Starting and idle trouble, codes P1298 and P1071

I can get you started with two things to consider. First, I would want to see the exact test results for the battery and the generator. Too many inexperienced mechanics do not understand what the numbers mean and incorrectly pass a generator with a problem. Specifically, all AC generators use six "diodes" which are one-way valves for electrical current flow. When one of those fails, the most that generator will be able to develop is exactly one third of its rated value. Your car uses a 70-amp generator which is very small for that era, but more than sufficient to do the job. With one bad diode, the most you will be able to get during a full-load output current test is around 25 amps. That is not enough to meet the demands of the entire electrical system under all conditions. The battery will have to make up the difference until it slowly runs down over days or weeks. Charging voltage, which must be between 13.75 and 14.75 volts, will typically still be okay, but two low-beam head lamp bulbs draw ten amps. The electric fuel pump, ignition system, and fuel injection system will draw another 15 amps or more. Now add the tail/running lights, radio, heater fan, radiator fan, ... And it is easy to see why the generator cannot keep up.

The second concern is one I only learned about in a class a few years ago, but never encountered myself. This only applies to Honda's, but I cannot remember which years. Many of their charging systems are computer-controlled, which is common on many brands, but on some Honda's, the many electrical "loads" are programmed into the computer, then that computer commands the generator to work just hard enough to meet the calculated load, and no more. All other systems look at system voltage which is much more accurate. If another load turns on, such as the radiator fan, that draws system voltage down a little. The voltage regulator sees that drop in voltage and in response, it runs the generator harder to produce additional current until system voltage comes back up where it wants it to be. On Honda's, the computer gets a computer signal from everything you turn on, like the head lights, radio, etc, and it adds up all those loads to calculate how much current it will take to run all of them. That is how much current it will command the generator to develop, and no more. Where people run into trouble is when they add electrical accessories to these cars. A good example is an aftermarket radio. That would not be monitored and the computer would not get a signal to tell it the radio is turned on. Same with an ear-damaging add-on amplifier, aftermarket fog lamps, and things like that. A simple radio can draw two to five amps. That current won't be included in the calculation so it will have to come from the battery. Even though the charging system is working exactly as designed, you could end up with a discharged battery after just a few hours to a few days of driving.

I am sorry I do not know more about that system or if it even applies to your car. Did you get a printout of the test results for the charging system? If you did, post the results for the "full-load output current" test, "charging voltage", and "ripple" voltage.

From what you described, relays and other systems are working, so do not waste time with those yet. Fan motors are already included in current demand calculations, however, a motor with tight bearings will draw higher than normal current. Typically that will cause a fuse or fuse link wire to burn open. I am more interested in the charging system test numbers. Those will tell us if that is where you need to be looking or if we will need to enlist the help of some of the other experts.