Dim Brake Indicator Always On

[firejackal]

I got an electrical gremlin going on with my 96 S14; within the last two months my "Brake" indicator on the gauge cluster will be lighted up very dim. When I use my ebrake it will go full bright like it's suppose to.

Does anyone know off hand what would be causing this?
According to the FSM that indicator goes off three places. The ebrake handle (which works), low brake fluid (which also works) then the alternator. I'm not sure how the alternator plays with the indicator, but I'm guessing maybe something is partially grounding out? All wiring looks fine, nothing burnt or cut.

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[Kingtal0n]

OOOooo

Thats a good one. I don't know.

I would be getting ready to change an alternator if I didn't know any better.

I suppose you could unplug it and see what happens to the light? try playing with the brake switch too. Not sure maybe someone else knows....

Something about the diode trio bugs me. If one of the diodes goes bad in the alternator, A/C current will be made available to the 12v coming off the 'charge indicator' bulb, and A/C looks like a ground to DC so that would light THAT bulb. But I take it yours isn't lighting THAT bulb. Do you ever see the battery light at all? Maybe the battery light doesn't work, and its also on but you can't see it.

[firejackal]

OOOooo

Thats a good one. I don't know.

I would be getting ready to change an alternator if I didn't know any better.

I suppose you could unplug it and see what happens to the light? try playing with the brake switch too. Not sure maybe someone else knows....

Something about the diode trio bugs me. If one of the diodes goes bad in the alternator, A/C current will be made available to the 12v coming off the 'charge indicator' bulb, and A/C looks like a ground to DC so that would light THAT bulb. But I take it yours isn't lighting THAT bulb. Do you ever see the battery light at all? Maybe the battery light doesn't work, and its also on but you can't see it.Thanks for the reply,

About three years ago I replaced my alternator because the battery light and srs indicators started going crazy (that was due to a wiring issue when I first bought the car). The current unit was a new denso.
During a cold start my voltage is at 13.6v, after warm it's between 13.1v-13.3v. Battery was bought new almost 6 months ago.
I wouldn't think it would be alternator/power issues, but I shouldn't rule it out.

Also, that dim brake indicator is only on when the car is running. And I did replace most of my cluster bulbs with LEDs.

I'm just hoping it's not a wiring issue somewhere under the dash and that I'm going to start to see more issues.

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[FaLKoN240]

Check for shorts...

[KoukiMonsta]

check your grounds under the dash and at the alternator first for potential easy fix. loose grounds are the most common and cause the weirdest shit to happen.

This is somewhat related to the thread I just posted about bulb check relay. My theory as follows..

Alternator/charge system, brake, and ebrake share a circuit.

the light is barely on, so it is being grounded when it shouldn't be. or as pointed out by Kingtalon some weird shit might be happening w/ AC [alternating current not air conditioning..]

So If it is grounding, why is it going to ground? the alternator goes to ground when it is not running..might want to get it tested.

[firejackal]

Check for shorts...

As I mentioned in my first post, I already checked for any visible shorts.
Now there could be some hidden under the dash where I cannot get access to or see.

check your grounds under the dash and at the alternator first for potential easy fix. loose grounds are the most common and cause the weirdest shit to happen.

This is somewhat related to the thread I just posted about bulb check relay. My theory as follows..

Alternator/charge system, brake, and ebrake share a circuit.

the light is barely on, so it is being grounded when it shouldn't be. or as pointed out by Kingtalon some weird shit might be happening w/ AC [alternating current not air conditioning..]

So If it is grounding, why is it going to ground? the alternator goes to ground when it is not running..might want to get it tested.

Since I got time today I looked into a few more things, started disconnecting components in that equation.
And the first one and perhaps the culprit; the brake fluid level sensor; the dim indicator light went out when I unplugged it.

1) I made sure the connector was clean (making sure there was no partial contact between the pins.)
2a) Used my multimeter on it, continuity test was fine, circuit closed when the float all the down, opened with it up.
2b) Checking ohms, it read nothing until the circuit was completely closed, at that point it read 1.2ohms ... which I honestly think is too high.
3) I did noticed the float didn't want to return to the full position some of the time. So that might require me to clean it out, might have gunk, or just wearing out.

I'm not going to close this out until I look more into the wiring.

Off topic from that I plan on eventually removing my whole dash to repair the cracks in the dash, and to finish the wiring for the air inlet motor (A while back I did the auto climate control swap). So during that time I will be inspecting everything.

Thanks for the suggestions so far guys; I appreciate the replies.
I don't get on here much, but I'm trying to more often again. I got plenty of DIY I still need to write up as well.
And I have too much projects now to keep up with, still got my 91 honda crx that I've been trying to sell, a 88 toyota supra that I swapped a 2jzge motor in (but I don't like that car much), and now a 00 bmw 328ci that I've been making into my DD, until then the s14 is still my current go-to DD, so I need to keep it running perfectly (and that I'm picky with the smallest of issues.)

[LoSt180]

Thanks for the reply,

Also, that dim brake indicator is only on when the car is running. And I did replace most of my cluster bulbs with LEDs.



Did you replace the brake light indicator bulb with an LED? If so, that's your problem. There might be a little bit of current coming from a switch, or the fluid sensor since that's a float. It won't be enough to light an incandescent bulb, but can cause an LED to to light up since they don't take much voltage anyway.

[firejackal]

Did you replace the brake light indicator bulb with an LED? If so, that's your problem. There might be a little bit of current coming from a switch, or the fluid sensor since that's a float. It won't be enough to light an incandescent bulb, but can cause an LED to to light up since they don't take much voltage anyway.I had a LED bulb in there, replaced it with a regular incandescent bulb and it still dimly lit it.

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[LoSt180]

Just went over your post again.

Looks like you've isolated it to the brake fluid switch. It probably has something going on internally causing some partial continuity.

The measurement one 1.2 ohms is perfectly normal when in the closed position. It's just a switch, you don't want much resistance. And 1.2 ohms is practically nothing.

This thread has me actually curious why the brake warning lamp is tied to the charge warning lamp at all, lol. That connection with the diode is removed on the S15. It looks like you can just snip a wire on the back of the cluster to remove that part of the equation. I can only guess that it's some kind of backup warning in case the battery light is burnt out.

[firejackal]

Just went over your post again.

Looks like you've isolated it to the brake fluid switch. It probably has something going on internally causing some partial continuity.

The measurement one 1.2 ohms is perfectly normal when in the closed position. It's just a switch, you don't want much resistance. And 1.2 ohms is practically nothing.

This thread has me actually curious why the brake warning lamp is tied to the charge warning lamp at all, lol. That connection with the diode is removed on the S15. It looks like you can just snip a wire on the back of the cluster to remove that part of the equation. I can only guess that it's some kind of backup warning in case the battery light is burnt out.I might look that connection over and decide on removing on it. But it's just not that is different on different 240sx models.

Look at the usdm s14 verses the sr20 Silvia version on the AC triple pressure sensor; the sr20 version has one of the wires running directly to switched (and fused) 12v, while the usdm version that same wire runs to the ecu instead.

The whole reason in this thread to was to (1) make sure there wasn't a serious issue looming, (2) have this for archival purposes for others.
For now I've been ignoring the light, I'll update this if anything else happens.


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