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Backyard Mechanic
BACKYARD MECHANIC: Indicator light signals problem with battery
A 1998 Oldsmobile Silhouette. A van is one of the most difficult vehicles to heat.
QUESTION: My car is a 1992 Buick Century and the problem is the battery indicator light. All the dashboard warning lights glow brightly when the key is first turned on except for the battery indicator light. It only shines very dim. After the engine is started, all the lights go out as they should.
The battery tests 14.5 volts now. I have had two new batteries and two new generators installed in the last 30 months. Can you help solve this problem?
ANSWER: You are correct in assuming the battery indicator light should be as bright as the other warning lights. The dim light indicates a problem. It could simply be a bad bulb, but the frequent replacement of the battery and alternator would indicate a different problem.
To test the bulb circuit, turn the key on, remove the electrical plug from the alternator, and ground the wire at the plug's "L" terminal. This should turn the battery indicator light on bright. If it's still dim, you have a problem with the bulb or wiring.
If the bulb shines brightly when you test the circuit, then the voltage regulator inside the alternator is faulty. The alternator and regulator are replaced as an assembly. So why do the alternators require replacement so often?
A bad battery can cause the alternator to be overworked and fail because of high heat loads. Conversely, an alternator that is undercharging or overcharging will cause the battery to fail. You have had enough batteries and alternators replaced to likely eliminate them as the cause. I would look at the battery cable connections.
A bad battery connection is sensed by the voltage regulator as a partially discharged battery. The regulator turns the alternator on more to charge up the battery, but this can cause the alternator to fail because it is working too hard and overheats. Then the battery discharges.
Another item to check is the battery hold-down and tray. A battery that is bounced around because of a missing hold-down or broken battery tray will soon fail. The plates inside the battery vibrate until they break and short out internally.
QUESTION: I purchased a 1998 Oldsmobile Silhouette van and the heating system doesn't work well in our winters. At -30 C to -40 C temperatures, the van takes hours to warm the interior. At -20 C it takes over an hour before the van is comfortable inside.
My dealer has replaced the thermostat, removed the a/c pollen filters, installed a larger heater and fan, and insulated the heater hoses under the van. GM and my dealer tell me there is nothing else that can be done. Do you have any feedback on this problem?
ANSWER: You are not alone in heating complaints. Part of the problem is that the engines in many newer vehicles are mainly made of aluminum, which dissipates a lot of heat before it gets to the vehicle's heater. The second problem is that the vehicles are too fuel-efficient. Modern fuel-injection systems and engine designs are miserly, especially at an idle.
Fuel must be burned to produce heat, and if the engine isn't burning much fuel, then there is very little heat. Put a load on the engine so more fuel is burned and the heater starts to work much better.
You've already had the thermostat changed, but the new one may be faulty. For the heating system to work, the thermostat must be completely closed until the engine is up to operating temperature. If it's open even a little, then the engine will never warm up at idle. I've seen many new thermostats that were faulty, so it would be best to have it removed and tested, or another new one installed.
Install a weather front on the van during cold weather. Cold air flowing through the engine compartment cools the engine too much. Block as much air as possible.
A van is one of the most difficult vehicles to heat. It has a large interior volume and lots of glass area. Operating the heater fan on medium rather than high speed will help warm it up, as air entering the vehicle will have time to be heated by the heater core.
Jim Kerr is an experienced mechanic, instructor and member of the Automobile Journalists' Association of Canada.