1997 Toyota Corolla HMSL stays on

1997 TOYOTA COROLLA
95,866 MILES • 4 CYL • FWD • AUTOMATIC
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US90NA
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I noticed the tail lights not working when the head lights were on (neither were the instrument cluster lights). But when I pressed the brake pedal the tail lights and high mounted stop light (and cluster lights) illuminated. I replaced the fuse and the lights worked for 10 minutes then blew again. I noticed the HMSL bulb was discolored so I replaced it.

Now when I turn on the head lights the high mounted stop light stays on as if the brakes are being applied. Additionally, when I press the brake pedal the tail lights do not get any brighter.

When I do not have the head lights on, the system works fine, no "extra" lights are illuminated, and when I press the brake pedal the tail/hmsl lights illuminate as expected.

I have checked the rechecked the fuses. Just perplexed at the moment.


Thanks!
Sep 12, 2009 at 11:38 PM
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BMRFIXIT
  • ✓Experienced Mechanic
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I would suspect one out of two possibilities
check if was a wrong bulb was installed and or if damaged socket
check for short and or bad ground wire
Sep 13, 2009 at 12:59 AM
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US90NA
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[quote:0882cc4c99="BMRFIXIT"]I would suspect one out of two possibilities
check if was a wrong bulb was installed and or if damaged socket
check for short and or bad ground wire[/quote:0882cc4c99]

The short may make sense but the bulb issue does not. The car worked fine with the original bulb. The original bulb was in place when the "always on" hmsl issues started. I only replaced that bulb when the circuit started blowing fuses. I never thought that a bulb could cause a shorting action since in my experience a bulb blows under overload.

And now the system does not blow fuses with the replacement bulb, but I still do not have brake light functionality(i.e. does not get brighter when I press the brake pedal). So I have "running lights" but no "brake lights".
Sep 14, 2009 at 1:20 AM
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MMPRINCE4000
  • ✓Experienced Mechanic
  • 8,548 POSTS
The bulbs are rated by wattage, just like a 40-60-100 watt household bulb.
If you put a bulb that has more wattage than the circuit can stand, you can cause the fuse to blow, or a short in the pigtail.

I would also inspect the pigtails, looking for burn marks on the plastic where the bulb plugs in.
Sep 14, 2009 at 2:24 AM
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