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Q: Electrical/cooling system on 1991 Saturn SL2

The radiator has a hole. Aware of that. We thought the thermostat was in need of repair so we replaced that. Test drove and the heat went straight between hot and cold, battery light came on, check engine light came on, shift to D2 light came on and so did my anti-lock light. I've only seen the anti-lock light come on while driving on ice. So that was wierd. When I got off the freeway, the car gave a jolt and then all lights dimmed. When I accelerated, the lights illuminated to normal levels. Please help me. I can't afford a car payment. I need this car to last a little while longer. I am also 8 months pregnant. Please, any advice would be extremely appreciated!
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The reason the lights dimmed is because the alternator has gone to it's happy hunting ground for alternators. The overheating problem is no longer the small leak in the radiator, because the radiator has been replaced. The relay for the cooling fan shows voltage between the terminals that activate the solenoid, but I assume that the amperage is insufficient to close the switch. The cooling fan comes on if the switched terminals are bridged with a jumper. As long as the cooling fan runs while the engine is at idle, then the temperature does not pass middle mark on the temperature guage. While driving the car at 35 mph or higher, I did not encounter any overheating problems until I had to wait in traffic for signals to change. All that I've read says that the PCM is fairly bullet-proof in these cars. The temperature sensor was removed and tested in the 50 to 80° F range and showed 250 ohms of resistance. In boiling water (195°F) at approximately 5000 feet elevation the readings were around 3,500 ohms which is within specification. Although the temperature sending unit was tested, not corroded and the connection was tight, I would still replace the sending unit just because it's easily accessible and fairly inexpensive. Hopefully, this will be the culprit!
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