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I have a 1986 Mazda rx7 FC I just finished getting it running and the brakes working. But when I went to drive it a 9o clock ish the headlights don't work my fuses are good running lights work brake lights work and indakaters work. I am not getting power to the backs of the headlights. Any suggestions?
Ok. Heres a good place to start. Check out the body electrical section for the car, either at rotaryheads.com, or foxed.ca and have a look at the circuits. Identify the circuits that aren't functioning. In your case, headlights and taillights, and whatever else. Rather than drive yourself into madness, go through those troubleshooting sections first and try to see if you can resolve the problem there. If you are certain to have narrowed it down to the CPU, you can either try to buy a new one, which might fix your problem, or repair it (if you can figure out what is damaged). Start with the individual systems and trace them back to a single point of failure. Sometimes you can have 2 separate problems show up, like a mouse chews through a wire bundle and gets more than one. Make sure that the separate systems are intact and work your way back to the CPU.
If your search leads you to the CPU, the next step is to verify how it isn't working. The manuals are a bit poor in this area. The wiring diagrams are goofy and difficult to discern. I had to do the following to determine my CPU was bad. Using your manual, go through and put information together so that you can identify the inputs and outputs. From here you can check with a multimeter to see if you have the appropriate voltages on the right wires. If the CPU has failed, your outputs will definitely be off, not outputting voltage, and you can also have inputs that are either permanently open (have voltage, but no amp draw), or permanently closed circuit (low voltage, full amp draw, can have smoke). From here you will have to either get yourself another cpu or try to fix it yourself. It sounds daunting, but with a lot of pictures and logical thinking, the points of failure can be identified. In my case it was mainly the electrolytic capacitors, and the other components they caused to rot.
You need a digital multimeter.. first, for good measure, check that you're not getting juice to the headlamp sockets. If not, the next place I'd look would be whether or not you're getting power into the relays. If not, pull the instrument binnacle off and backprobe the headlamp switch to see if power is leaving the switch with it in the on position or not. As pyro mentioned, you'll figure it out eventually. Really all you need are the wiring pinouts so you know what you're probing.
05-29-18, 07:34 PM
