Well, a gremlin has popped up in the electrical system in the Nova. When the key is turned to the accessory position, the screen on the EFI hand controller flashes on and off a couuple of times a second. I pulled the EFI fuse and found there was about 3 volts being fed into the ignition circuit. After a lot of head scratching and looking at wiring diagrams, I found that if I pulled the fuse for the dome lights, it stopped. The only connection the two circuits have is that the dome light dimmer is connected to the ignition circuit so that the dome light will go out when the key is turned to the on or accessory position. So, I figured that if I put a diode in the ignition feed to the dome light controller, that should stop it. In addition, the backlighting on the instrument cluster backlighting was really dim. As much as I hated to do it, the dash was going to have to come out to get access to the dome light module and the backlight bulbs. I got it out, replaced the bulbs with LEDs, installed a diode in the ignition feed lead, and made a few other changes to clean up the wiring. Confident all was fixed, and before I put the dash back in, I tried the switch in the accessory position, and no flashing. Great!
I put it all back together, but when I tried it again, the flashing was back. Plus, now the wipers don't work.
Many NSFW expletives followed.
The fuse on the wipers was blown, so I checked the wires on the wiper motor and switch and found no problem, I replaced the fuse and as soon as the ignition switch was turned on, it blew. On the Nova, power is applied to the wiper motor whenever the switch is on, and it is controlled by the switch supplying a ground to either the low or high speed windings, or both.
After stewing about it for a few days, I decided to bite the bullet and pull the dash back out. I had thought that somehow a wire had gotten pinched causing the short, but found no problem, and the short went away when I unplugged the wires from the wiper motor. So, it seems the motor just all of a sudden went shorted internally, even though it had worked fine whenever I had tried it before. I'm going to pull it off tomorrow and tear it down to see what the problem is, and if I can fix it. It's 55 years old, so I'm sure the warranty has expired. Fortunately, if I need a new one, they are readily available and not expensive.
As for the ignition backfeed, I'm going to try a few things to see if I can figure out where it is coming from. Since the wiper delay module and the radio delay module are also connected to the ignition circuit, maybe its one of them causing the problem, but I don't think they are connected to the dome light circuit. The puzzling thing though, is that it doesn't happen with the instrument cluster disconnected, but that only connects to the turn signal indicators, high beam indicator, fuel gauge, idiot lights and backlights. the only bulb directly connected to the ignition circuit with the engine off is the generator light, but the wire that grounds it to make it come on isn't connected.
Color me puzzled....
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