Questions and Answers
210 Electrical Problem
Q. Dear Mr. Ciulla, I have a 1980 Datsun 210, 185,000 miles, MT, 1.4 liter engine, no A/C, normally aspirated. For the last four years it has been a model of reliability and economy. Now it has developed a mysterious electrical ailment.
Condition: Starting with ignition key. Key turned to ON, all the appropriate lights come on, all electrical devices work. Key turned to START. Voltage at starter goes to 0, battery discharges as if the terminals are shorted. When the key is turned back to ON, dashboard warning lights come on dimly and any activation of electrical devices, (wipers, turn signals, etc.) will cause the electrical system to fail altogether. Removing the battery positive cable and then reattaching causes the system to "reset".
When the ignition wire is disconnected from the starter and the key is turned to START, voltage at the ignition wire is 12V, with no occurrence of the above problems. Removed and bench tested starter, works just fine. Have cleaned all ground connections. Have removed the ignition switch harness and tried jumping the terminals. Same condition occurs.
Condition: Engine is running. Car can be push started; in fact it starts quite easily. Starter will activate when the engine is running. Dashboard brake light stays on, carburetor dashpot sticks in the full open position so the car does not go to idle. Voltage at battery terminals is 14+ volts.
Additional note: Have noticed that when the key is turned to START that the tachometer will rise to about the 3,000 rpm mark (this is with the engine not running) and then fall swiftly back to 0. This is very much like watching a capacitor charge and discharge.
Suppositions: There is obviously a dead short occurring when the ignition switch is turned to START. The battery is discharging straight to ground. The fusible links appear to be undamaged.
Thanks for your time!
BlairA. The Datsun B-210 and 210 have to be my all time favorite car. At one time I had several of them in my yard. I would buy them, fix them up and sell them. Some of the cars I sold went well into the 300,000 mile range. I had a blue 1978 Datsun B-210 hatchback with a four speed that was my favorite. It was still getting 45 mpg at 410,000 miles when I had to let go of it. The body was too far gone to keep it on the road.
Anyway, I agree with your supposition about the short circuit. The electrical system is so simple that troubleshooting them is fairly easy. The first thing I would do is to swap out the alternator. Most of the symptoms you describe can be attributed to a bad diode pack in the alternator.
If you still have the problem, you'll need to trace out the wiring. I would physically check each engine harness to make sure there are no bare wires shorting to ground.
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