Intermittent Brake light in dash (1 Viewer)

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Nov 21, 2021
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I drive my cruiser every day but rarely use the handbrake/parking brake. I’ll engage the brake 3-4 times a month just to keep from seizing. Sometimes after I’m parked overnight without the handbrake engaged the brake light will be on in dash upon starting and stay on for a couple miles of driving. Brake is not engaged and the light won’t go off by raising and lowering the handle. Is the brake light in dash associated with the driving brakes? This has only happened when it’s very cold, say 0-20F
 
I would check the brake fluid level sensor. It's made into the master cylinder cap.
 
The fluid level is one, the second would be to check your emergency brake to make sure that it has tension to keep it down, if it pulls up slightly the brake light will come on.
 
I would check the brake fluid level sensor. It's made into the master cylinder cap.
Just had a look, fluid in reservoir is 1/4 inches above min line. Certainly not full but not warning light low.
 
The fluid level is one, the second would be to check your emergency brake to make sure that it has tension to keep it down, if it pulls up slightly the brake light will come on.
Thanks, I’ll check that out too.
 
Just had a look, fluid in reservoir is 1/4 inches above min line. Certainly not full but not warning light low.
If the cap is not on tightly, it could also cause the warning light.
 
I did pads/rotors on my truck last summer, haven’t done anything with the brake fluid. How do i top it off? Aside from removing cap and filling. I don’t know what fluid was used, saying that its fsm specified would be a gamble. Can I just top it off with the recommended brake fluid? Any issues with potentially mixing different fluids? Fluid in reservoir is orange and looks clean if that means anything.
 
Brake fluid expands a little when warm, in the morning it might be cold enough to trigger the light as the under bonnet temps rise as does the fluid in the brake lines it may just be enough to trigger the light?

There is something that many do not realise, the fluid level when correct with new pads and discs will trigger as the pads start to wear near minimum, many 'fiddlers' keep topping up the fluid every time they see it has gone down a couple of mm, so the warning is no longer going to work.

Regards

Dave
 
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Any issues with potentially mixing different fluids?
Absolutley, DOT 4 is better than DOT 3, but do NOT use DOT 5! There is a numbering cock up, I mean it's only the brakes FFS!! DOT 5.1 is another you can use but I would not hunt it out.

Regards

Dave
 
Absolutley, DOT 4 is better than DOT 3, but do NOT use DOT 5! There is a numbering cock up, I mean it's only the brakes FFS!! DOT 5.1 is another you can use but I would not hunt it out.

Regards

Dave
What’re the chances there’s already DOT5 in it? If there’s DOT3 can I top off with 4? I know the correct way would be a complete flush and replace, but it’s cold and my LC won’t fit in my garage. Will potentially running mixed 3 and 4 be ok for a couple months?
 
Same thing has just started happening on my LX470. It's currently the coldest weather we've had all year, but the problem still happens even when it's been up to 50*F. The light goes off if I brake harder than normal (nosediving the truck) but comes on again once I let up. The fluid is near the max level. The e-brake handle feels loose (which is new).

Thanks to those who suggest the fluid level sensor. I'll check that out ASAP.
 
Same thing has just started happening on my LX470. It's currently the coldest weather we've had all year, but the problem still happens even when it's been up to 50*F. The light goes off if I brake harder than normal (nosediving the truck) but comes on again once I let up. The fluid is near the max level. The e-brake handle feels loose (which is new).

Thanks to those who suggest the fluid level sensor. I'll check that out ASAP.
Interesting, it’s only happened to me 2-3 times over the last month and just goes away. Hard breaking hasn’t seemed to affect it.I’ll continue to check through everything that’s been mentioned. Will report back if I find an obvious issue
 
Every time it’s happened to me (1997 80, 1998 4Runner) it’s been a low fluid issue.

Never below the “low” indicator line, but always resolved by bringing fluid level to “full”.
 
Every time it’s happened to me (1997 80, 1998 4Runner) it’s been a low fluid issue.

Never below the “low” indicator line, but always resolved by bringing fluid level to “full”.
Thanks, after reading all the responses I’m thinking/hoping that’s my issue. Makes sense with my level being towards low, and happening on colder mornings relative to what Dave mentioned. I’m going to top it off first thing tomorrow morning, I’ll be interested to check fluid level when it’s 0F
 
Just had a look, fluid in reservoir is 1/4 inches above min line. Certainly not full but not warning light low.
Test that the switch is showing normally open and that it closes when the float goes up.
 
@pjs1193

The sensor in the cap can go bad as well. If you add fluid and the light stays on then a cap replacement might be in order.
 
Circling back, I added brake fluid back to Max line in reservoir and haven’t had the intermittent brake light since. Will continue to monitor.
Thanks!
 

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