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Head Scratcher

I own a 98 Dodge 1500 4x4 Truck - not to worry, my everyday car is a Kia Rio. I have wierd electrical problems. During the day, with the headlights off, both turn signals work fine but when I step on the brakes I notice the radio light / clock dims. At night, with the headlights on, the right signals works fine but the left signal goes on and stays on without blinking. However the dash lights do not dim when I use the brake.

It sounds like one of your signal lights on the left has a burned filament and the rest of the porblems would be dirty or corroded grounds. You will have to go to each light and clean the grounds. Check the battery terminlas are all cleaned and free of corrosion.

Second the bad ground diagnosis. You’ll want to check the grounds at the lamps, but you’ll also want to check the body grounds to the chassis and the engine as well.

Check all bulbs. One is burned out. It may even be the left front signal bulb.

Yah, definitely a grounding issue. Or earth issue, depending upon your frame of reference. Oh, is that a pun? Remember to check body to frame chassis to engine ground connections like JayWB says and you’ll be in fine shape.

Thanks all…I have checked all the blubs and they look good. I will check the grounds - if ever stops raining.

Check that your side & stop light bulb are both in the right way round. The pegs are staggered, you shouldn’t be able to install them wrongly…but some people do manage it somehow, usually you can’t get the bulb correctly fitted backwards but can get it half way in, the teardrop bulb contacts on the base of the bulb can cause a short between the side and stop light circuits and strange things start to happen.

Just like your clock dimming when you hit the brakes, the short is passing power back to the panel light circuit when you hit the brake and the circuit thinks you have just turned your side lights on and dims the clock to the night setting.

There is something else to check in regards to bulbs and this may not be widely known.
The bulb filaments may be good but the bulb may have a bad connection where the prongs of the socket make contact with the domed lead contacts on the bulbs.

What happens is that over time vibration allows the harder metal in the prongs to vibrate the dome off of the contacts and the contacts may become concave. This can cause weird problems but the only way to verify it is by removal of the bulbs and visually inspecting the domes to see if they are still domed or if they’re now flattened. Hope that helps.