Brake light stays on

[deejay1272]

Hi everyone. Long time, no post.

Warmer weather looks like it may be sticking around in the Pacific NW so it's time to address some outstanding problems with my "Ter-Junk-en" (as my friends call it - can you believe that?)

Anyway - the red "brake(!)" dash light that indicated that the parking break is engaged seems to be stuck in the "on" position. I imagine that the FSM has something in it to address this problem, but I thought I'd come back to see if anyone has experience with this before digging into it (also, I just wanted to let you know that I'm still alive!)

[ARCHINSTL]

Do some Searches here for that - seems that it could be related to an alternator event.
Tom M.

[garyfish]

Could be something as simple as being low on brake fluid. I'd definitely check that first.

possibly useful thread:
http://www.tercel4wd.com/forums/viewtop ... f=4&t=1604

let us know what you tried, and what worked or didn't work... it'll add to the knowledge base here

[takza]

Low fluid....hand brake not fully down...can be related to charging issues?

[garyfish]

Do some Searches here for that - seems that it could be related to an alternator event.
Tom M.

If it's just the brake warning light, it's unlikely to be alternator-related. If it's the brake and charge lights, it's probably due to problems in the charging system, particularly the alternator and/or voltage regulator. I just went through this, and discovered that the brushes in my alternator were worn out and needed to be replaced. Luckily I had a spare alternator and just swapped in the "plastic brush block" from that one... gonna solder in new brushes so I'll have another spare alternator ready to go. The FSM and the following thread provide good descriptions of the process (I didn't even need to remove the alternator to replace the "plastic brush block"):
viewtopic.php?f=7&t=4040

[SethM]

I had this problem on my 85 T4WD from the moment I bought it last year. I did a search on the forums here, read up on cleaning the switch at the base of the handbrake lever, fussed with that for a bit, light still ON all the time.... went back to my search results and saw something about the fluid level being involved--- checked my master cylinder where the level looked perhaps a tad low but not too bad. Filled it up to the top mark. Light's been off ever since! Might work for you....

[ARCHINSTL]

garyfish is certainly right on this one - I'd forgotten that the brake and alternator lights had to be on concurrently for an alternator event. I'd also presumed that you'd already checked the fluid level.
Tom M.

[RiggerRob]

in my experience, if the brake fluid level is just a tiny bit low the brake light will come on and stay on. If you have even a small leak in the brake system the light will come on pretty frequently. Just my 2 cents...

[tercelwill]

I had the same problem with my terc and was able to fix it. first make sure you don't have any leaks in your braking system.
the way it works is that the float and lever are switches that give the circuit ground when they are tripped( the float low or parking brake up)

check brake fluid if low top it off
take off the mc cap and turn it over that way the float thinks the mc is full
if that doesn't turn off the light unplug the connector to it. if it shuts off then replace the cap

no luck?
unplug the connector to the parking brake if that shuts it off just replace the switch

if it doesn't shut off then it's gonna get tricky. which was the case with mine

the light circuit is finding ground somewhere so get a wiring diagram if you can. you'll see that the ground side runs to the charging system but stopped by a diode so then it runs the choke circuit of all places. so inspect the circuit for a short to ground somewhere. it could be an exposed wire or current could be slipping past the diode and grounding through the charging system.

definatly a head scratcher, a toyota mechanic of twenty years was as stumped as i was.

but most likely it's one of those 2 switches
goodluck

[Petros]

in most cars there is one other switch beside the low fluid and parking brake that can give you a brake warning light. If there is differential pressure between the front and rear brake systems a switch in the proportioning valve body of the brake system will be tripped, and the light goes on. This is intended to show if one of the two brake systems has low pressure. Cars have had this since they switched to a duel front/rear brake system over 40 years ago.

It is not common, but it is one other system malfunction that can trip the brake warning light. So if it is not the low brake fluid float switch, and not the parking brake switch, it could be that you have differential hydraulic pressure in the brake system. That means you have to either find the source of the leak in the system, or replace/rebuild the master cyl.

Good luck.

[splatterdog]

Hold on Petros! I wouldn't say most cars have the pressure differential switch anymore. In fact they are pretty much extinct since abs is mostly standard these days. And I don't recall any Asian cars ever having one since at least the 80's. Tercel included. They rely solely on the reservoir switch to let you know there's a problem. The domestic's have been doing it that way for quite a while too.

While this warning method won't turn on the light because of an internally leaking master, a pedal on the floor will give most drivers an idea that there is something wrong.

Low fluid or parking brake switch here. Maybe if you are really unlucky, it's a wire rubbed thru to ground somewhere.

[Petros]

Hold on Petros! I wouldn't say most cars have the pressure differential switch anymore. In fact they are pretty much extinct since abs is mostly standard these days.

well yes that is true, but if you get low pressure in the ABS systems you will still get a brake warning light (it just says "ABS" on it). I know our Ford van always has this warning light on (it reverts to manual brakes, which I prefer anyway since the ABS is for people who do not know how to modulate brakes properly). And no one at Ford can tell us why the ABS system is not functioning since all the comments check out, and there is no error code in the brake memory, thanks Ford. And our cars do not have ABS anyway, which is just fine with me.

And I don't recall any Asian cars ever having one since at least the 80's. Tercel included. They rely solely on the reservoir switch to let you know there's a problem. The domestic's have been doing it that way for quite a while too.

You are probably correct since I do not recall seeing a lead coming off the proportioning valve in the Tercel (I will check tonight). I have seen it on my other (older) cars, including several Nissans. I assumed they would not have deleted this system on the Tercel. It was useful I think in helping determine what needs to be replaced when the brakes go mushy.

[tercelwill]

I'm gonna have to second splatterdog there is no pressure diff switch on the tercel. The only two switches that can turn on the light are the float switch and the parking brake switch both put the light to ground. the terc was designed with tried and true Toyota technology. i just can't figure out why this circuit is tied into the emission control system. look at the wiring diagram it's weird.

[Neu]

Just chiming in to say this, if the brake light is on due to low fluid levels, it is SLIGHTLY DIMMER than when you pull on the hand brake. If you pull on it, it will lighten/get more bright slightly, that's one simple way to tell at least.

[deejay1272]

check brake fluid if low top it off
take off the mc cap and turn it over that way the float thinks the mc is full
if that doesn't turn off the light unplug the connector to it. if it shuts off then replace the cap

no luck?
unplug the connector to the parking brake if that shuts it off just replace the switch

if it doesn't shut off then it's gonna get tricky. which was the case with mine

the light circuit is finding ground somewhere so get a wiring diagram if you can. you'll see that the ground side runs to the charging system but stopped by a diode so then it runs the choke circuit of all places. so inspect the circuit for a short to ground somewhere. it could be an exposed wire or current could be slipping past the diode and grounding through the charging system.

definatly a head scratcher, a toyota mechanic of twenty years was as stumped as i was.

Well, I know that my fluid level is legit. Also, I tried unplugging the electrical connection that is attached to the brake fluid reservoir and the light went off, but as soon as I plugged it in again, the light went back on. So at least I can eliminate the concept of taking my center console apart to investigate. It has to be associated with the electrical system (poor ground perhaps). This won't be very fun to fix at all!

Can you tell me, in general terms, where I should start looking (behind the glove box, behind the climate controls, etc)?