ST185 break light turns on upon hard acceleration

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ST185 break light turns on upon hard acceleration

Postby r-town » Mon Sep 25, 2017 3:36 pm

Anyone experienced this issue before? When I launch my Alltrac the break light turns on for a few seconds then turns off. I already checked the parking break sensor, and looks ok. Any thoughts on what might be causing this?
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r-town
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Re: ST185 break light turns on upon hard acceleration

Postby 93celicaconv » Wed Sep 27, 2017 12:13 am

Assuming the brake light you see is the one in the instrument cluster, not a rear tail lamp?

If so, your brake fluid reservoir contains a float switch. Your brake reservoir fluid may be low, and the acceleration may cause the level to shift enough to trip the low level switch in the reservoir cap. Check that.
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Re: ST185 break light turns on upon hard acceleration

Postby r-town » Wed Sep 27, 2017 12:19 am

93celicaconv wrote:Assuming the brake light you see is the one in the instrument cluster, not a rear tail lamp?

If so, your brake fluid reservoir contains a float switch. Your brake reservoir fluid may be low, and the acceleration may cause the level to shift enough to trip the low level switch in the reservoir cap. Check that.


Yes, its the light in the instrument panel. That was my first guess as well, but the reservoir looks to be full. Although the fluid looks like it has seen better days.
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Re: ST185 break light turns on upon hard acceleration

Postby 93celicaconv » Wed Sep 27, 2017 12:34 am

If I remember correctly, both the brake fluid level switch and the parking brake switch are normally open switches (meaning when they are in their acceptable states, they are open circuited, so the brake light in the instrument cluster is not grounded, so it is not lit).

If you disconnect your wiring harness at the brake fluid reservoir cap, with the key in the ignition and turned ON, the brake light should be out. Try your acceleration again. If the brake light does not come on, you have a problem with the brake fluid level switch. If it does come on like your prior experiences, reconnect your brake fluid level switch to the wiring harness, then remove the wiring connector at the parking brake switch and do your acceleration test again. If the brake light now stays off, you have a problem with the parking brake switch. If the brake light still comes on, you have something in your wiring harness that is grounding out your wiring to these switches (or either one of them) that is aggravated by the force of acceleration, or some other connection issue somewhere.
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