This problem just came up today while I was driving around. Checked the brake fluid level, which was fine. The two wire connections on the filler cap seem normal. No noticeable braking issues while driving. Don't know if it means anything but, when I pull up the parking brake handle, the dashboard brake light lights up a little brighter, and when I release the brake handle, the light turns back a little dimmer.

​​​​​Anyone else encounter such issues with their cars? And what was your particular solution?
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Check the pedal stopper pad.

https://honda-tech.com/forums/search...rchid=24581538

 

I don't think the pedal stopper pad is the issue. If you are referring to this attached pic, I already changed all three of these that are located above the brake pedal & clutch pedal.

I will have to check the parking brake switch to see that's the issue.

 

Here's a check list of what I've done so far (to diagnose my dashboard brake light being on with the parking brake lever disengaged and while driving):

1. Brake fluid level at MAX in the reservoir.
2. All four brake pads have 95% 'meat' left on them.
3. I did a continuity test on the brake fluid filler cap wires per the service manual and it PASSED.
4. All brake lights are in working order.
5. I did a continuity test on the parking brake switch per the service manual where, continuity should exist with the brake lever in the UP position, and NO continuity should exist with the brake lever down. However, I am getting continuity in BOTH positions.

It should be noted that the service manual instructs the parking brake switch connector to be detached, but I could not remove it; it wouldn't budge. So I left it be (for fear I would break the connector housing) and did the continuity test. Could this be the reason why continuity exists with the brake lever down, because it's still feeding signals to the dashboard brake light? Does the connector need to be removed for the test to provide the expected result? Hard to believe this would be the case, but I know very little about this kind of stuff.

Any other issues to be considered? Master Cylinder? I replaced it at 123K miles. (car currently has 184K miles). Does the MC have a sensor that can be replaced, rather than the entire unit? Hard to believe it would go bad already.

Checked everything up, down & sideways for any leaks and found none.

That's about what I've done so far. Any help from the experienced trouble shooters out there would be much appreciated.


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I wonder if your master cylinder cap is the problem, have you tested the cap with it being unplugged, check for continuity when the float is pushed up and none when it's down? Wondering if it's giving a false reading of it thinking the reservoir is low, my thoughts are in that direction because when you say you pull up the e- brake the light gets somewhat brighter showing another area in the wiring where it triggers the light to come on.. ? Shouldn't be too hard to find the problem hopefully!

 

I removed the cap by disconnecting the cap wires and followed the service manual: Continuity should exist when the float is in the DOWN position, and not exist when it is in the UP position. This was the result that I got.

However, you seem to suggest that continuity should exist with the float in the UP position and no continuity in the DOWN position, which is opposite of what the service manual is telling me. In actuality, when the float was in the UP position, I got no continuity, and in the DOWN position, I got continuity.

It makes sense to me that continuity doesn't exist in the UP position because if the reservoir is full (which makes the float go in the UP position), then there's no need for the the wires to send any signal that something is wrong.

I suppose it wouldn't be a big dent to my wallet to buy a replacement cap that cost around $32. An entire master cylinder replacement (that includes the reservoir & cap) costs around $66. Maybe I should just bite the bullet and replace the master cylinder. It'll be a lot cheaper than taking it to a mechanic.

 

I got the continuity mixed up with the float being up and down... my bad.. After re-reading your post, the test you did with the e brake switch seems like the brake is not being fully released. Have you jacked up the rear of the car and checked how much drag you have from your brakes when you free spin each rear wheel? Should be just ever so lightly dragging.. Could it be that the e-brake tension has self adjusted itself and is simply a bit too tight?
Edit: Just wanted to add that this may be what might occur with drum brakes..

 

I have this exact problem with my 1990 Civic Si. Dimly lit sometimes but bright when I pull the hand brake. I have never been able to solve it. Mine is a bit intermittent, it seems to go away after the car is warmed up. I have also checked everything you mentioned so far with the same results. I was thinking about looking for a short on the back of the instrument cluster. Perhaps there is some cross talk between some of the circuit traces printed on the plastic on the back of the instrument cluster. I will be watching this thread closely. I think the brake warning light systems on our cars are probably identical. Let me know if there is anything I can do to help or if you find the solution. For one test I completely bypassed both the hand brake switch and the fluid level switch and the problem did not go away. In my case at least it is clearly a short circuit somewhere but since it is intermittent I have never been able to track it down. I seems like as soon as I start fiddling with the wires in order to find the problem things move just enough so as to make the problem go away.

My previous thread on this problem

 

OK, so I have [apparently] solved my particular issue <knock on wood>. The question is, how much longer until this problem crops up again? You never know with these 33+ year old cars.

I followed the Honda service manual to test the continuity for the following:

Brake fluid reservoir cap wiring: PASSED
Parking Brake Switch: PASSED
Brake Warning Bulb Check Circuit: I didn't have to go this far, which requires pulling the ICU connector from the back of the fuse box to diagnose (which I wouldn't know how to do anyway).

​​​​Upon close examination, the Parking Brake Switch is a really basic part. It's just a spring-loaded plastic housing attached to a metal mounting clip that goes up when the brake lever is pulled up, thereby engaging the dashboard brake light, and when the brake lever is lowered to the bottom, it disengages the continuity and sends the signal to the dashboard brake light to turn off.

SIDE NOTE: If the problem persisted, as a workaround, I was prepared to just leave the parking brake switch unit not attached to the mounting point (i.e. not connected to ground), so that the dashboard brake light would be disabled.

​​​​​​I paid particular attention to the connector and sprayed it thoroughly with the CRC QD electronic cleaner spray. Made sure the connection was snugly reconnected. The parking brake switch is mounted with just one Philips screw.

The dashboard brake light functioned normally after that.

Initially I thought the new aftermarket ignition switch that I had installed recently had something to do with the issue. In fact, the first time I drove the car with the newly installed ignition switch was when the dashboard brake light came on. The original ignition switch was working fine as far as starting the car, but it wasn't passing the continuity test per the service manual, which is why I replaced it (for peace of mind).

Your particular issue could be different than mine, so take it FWIW. I was kinda doubtful just disconnecting the parking brake switch and cleaning the connector would solve the problem, but it worked for me. Doesn't mean I'm out of the woods, as this problem could reappear further down the road. However, I've never had this issue before, but it just happened to crop up since I replaced the ignition switch.

Below is a helpful bit of info I got from a CRX owner from another forum that might be useful to you. Worst case scenario, you can just detach the parking brake switch assembly from its mounting position to turn off the dashboard brake light. That [out of commission] dash light is not really a problem as long as you keep an eye on the brake fluid level and mindful of your braking system.

Happy hunting & good luck.

"The brake warning light gets power on one side from fuse no. 1 in the dash fuse box, which gets power from the IG1 contact (blk/yel, on in run and start) of the ignition switch. If the bulb lights in run and start, turns off in other positions, all that should be fine. On the ground side of the bulb there are three devices: the Parking Brake Switch, the Brake Fluid Level Switch, and the Brake Warning Bulb Check Circuit which is part of the integrated control unit. Since you've tested the others, try unplugging the connector from the integrated control unit. The ICU is the box snapped into the back of the dash fuse box. edit: I just realized the brake warning light wire doesn't go through the ICU's "A" connector, which is the one accessible from the outside - you would need to pry the whole ICU off the back of the fuse box to isolate it that way."
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Disconnecting the hand brake switch did not solve my problem when I tried it a few years ago.

 

Sorry to hear that. If you did the continuity test for the Parking Brake Switch & Brake Fluid Level Cap wires, and they passed, then there's really only one other option that could be at issue: The Brake Warning Bulb Check Circuit on the ICU connector. The above three aspects, to my knowledge are the only factors that activate the dashboard brake light.
I am not knowledgeable with what needs to be diagnosed once you pull the ICU out from the backside of the main fuse box. Hopefully someone else can provide input.
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Your particular issue seems more complex, but focusing first on the ground side of the brake warning light system would be the way to go, and then move on through a process of elimination. Also, you could have inherited a car (unless you're the original owner) that got worked on by a previous owner who screwed around and got the wiring wrong on some part of the car that is messing with your dashboard brake light. These things occur all too often, I have noticed.

 

Is there a button or something under the dash to cause this. Doesn't matter if the parking brake is up or down the light always stays on. I'm not concerned about it, it's just more of an annoyance.

 

Hey Geo,
Just wanted to let you know that I have solved my dashboard brake light issue, and my solution will most likely will apply to you as well: Either replace the ICU with a properly functioning unit, or repair it (if possible). I bit the bullet and bought a decent ICU on eBay, which resolved my issue. Had to pay more than I wanted, but the quick fix was well worth it.

I managed to pull out the ICU from the back of the dash fuse box and determined that the electrolytic fluid from the capacitors leaked out onto the circuit board (PCB). Apparently very corrosive and conductive liquid, so this was most likely the cause, by crossing and co-mingling between the circuit traces causing the dashboard brake light to remain on.

BTW, after I pulled out the ICU and then turned the ignition key to the ON position, the dashboard brake light did not come on, which is the obvious expected result. If, in your case, the dashboard brake light still comes on then I would surmise there's some wiring or circuit-crossing issue going on with the dash cluster.

Attached are pics of my original ICU. The burned-out looking areas are where the capacitors leaked out the electrolytic fluids, corroding and most likely causing the circuit-crossing issues. My guess is that your ICU looks similar.

If you've never dealt with the ICU & how to access the fuse box to remove it, let me know. I'll give you the steps I took to remove it. Unplugging the various connectors attached to the fuse box (to get more wiggle room) was a hassle, but it's do-able, with patience.

I'll probably try to repair the original ICU by replacing the electrolytic capacitors, and hopefully if the PCB trace patterns have some integrity left, it can be restored to its original working order.




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Please, starting with the location, is this under the dash or under the hood I have fuses in both locations.

 

It's the fuse box under the dash.

The easiest way I found to get access to the ICU was to disconnect several wire connectors that are plugged into the fuse box. But first, I would remove the two 10mm nuts holding the fuse box to the mounting frame. This will provide more wiggle room with the fuse box to get access to remove the connectors.
1. The pic below shows the connectors that I disconnected (circled in yellow highlight). The one on the left is the ignition switch connector. The middle one is a blue colored connector. The third one is on the top side of the fuse box (could be the main relay connector). These three connectors [on the front side of the fuse box] are what I removed.

2. The second pic [illustration] shows the backside of the fuse box. The highlighted areas are the connectors that I pulled.

You should now have enough room to turn the fuse box downward and about a 40 degree turn to the right so you can have access to pull the ICU from the fuse box.

The ICU housing has a plastic clip on top and bottom. You just need to undo one of the clips with a small flathead screwdriver and the ICU can be wiggled out from its socket.

That about describes what I had to do. Good luck.
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Thanks @edgeman61 for the instructions. I replaced the ICU with one from a junkyard. The junkyard part looked perfect inside not a single flaw that I could see, I was sure it was going to solve my problem. It did solve the brake light issue but it created an issue where the right front side marker stays on all the time so I swapped it back to my old one with obvious burn marks because the side marker issue is worse than the brake light issue. I would say that this is pretty convincing proof that the problem is in the ICU. Now I just need to find a good ICU. So I went online and ordered three more from various junkyards. Because some people think that the failure is caused by heat, I ordered my parts from junkyards in cooler parts of the country. Fingers crossed that one of them works correctly. Does anyone here see a flaw with the junkyard part that I didn't catch?


Top of the junkyard part

Junkyard part VS Original part

 

It's difficult to determine if the ICU will work properly just by eyeballing both sides of the circuit board, unless it's tested thoroughly. I had to take the chance and buy a pristine looking ICU from eBay. (which was a bit pricey) The guy who sold it claimed it was fully tested & in good working order and had a 30 day return policy, which gave me some peace of mind.

The problem with these ICU 's are that they are really old, and the capacitors will eventually leak out and lose their effectiveness. Over time, the heat definitely is an issue with these units. And nobody makes these ICUs anymore, which makes the situation more difficult.

Your junkyard part looks pretty clean on the soldered side, but I would closely examine all the traces with a magnifying glass, clean them thoroughly with Q-Tip & rubbing alcohol, and replace all the capacitors, then proceed from there.

I noticed that on the pic, if you take a look at the bottom section of the junkyard ICU pic, there are some corroded looking spots on the circuit board. Check it out with a magnifying glass, there could be some trace-crossing going on in that area due to the corrosion.

My ICU was pretty clean looking as well, and fortunately it functions properly. The problem with getting the junkyard ICU 's are that it's a crapshoot; you can get lucky with a good unit, or a bad one.

Just for the learning experience, I plan to change out the capacitors on my original ICU and try my best to get all the affected traces cleaned up. If successful, I can keep it as a backup.

There's a guy on this board who has been very helpful with giving me advice and recommendations about how to go about restoring my old ICU. His handle is RDC_PCB. You can try to contact him with questions. He's pretty good at responding and quite helpful.
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