Amber Brake System light on
 

Hi, I have a 2008 RDX non tech. On the last few extremely cold morning the amber brake system light came on and stayed on. I checked the owners manual and it said in extreme cold weather this may happen. It said to pump the brakes before you put the car in gear.
I did this and the light never went out. So I shut the car off and then restarted it, the light went out.
Any one else have this problem?

can't say that I have and i don't live in cold weather... makes sense though, if it's like super cold especially if you may be a little low on fluid.

Same thing happened to us last week when the temps were in the -20s. The light came on a few times then but we didn't notice any problems with braking and the light hasn't come on since.

Like many newer cars, the RDX has an electric vacuum pump for the brake system. The amber brake light indicates low vacuum, which isn't too unusual in very cold temps -- the pump should catch up after a short time. (If it stays on of course, get it checked.)

The red brake light indicates low brake fluid. This can be simply from pad wear, but it can also be a serious braking problem. Red should get your attention right away.

Thanks XLR8R, It stayed on while I drove on the 2 extremely cold mornings (6 degrees one day and below 0 the other time).
But as the temps. have warmed a bit I have Not seen the amber light come back on. I will check with my scanner sometime and see if it set a code!
Just wasn't sure if I should take it back to the dealer while under warranty!

i have this problem whenever i leave work and the temp is low (1 degree, etc). i never have this problem when i leave my nice warm garage at home.

It's nothing to worry about its cause the electronic brake system is outside and it doesn't like cold weather there's just not enough voltage when it's cold but when it warms up the light goes out there's really no fix for it

Its a small seal that could be changed. It only happens on really cold days happened to me.

ah good to know. i kinda thought it was only cold-weather related.

What seal?

Same thing happen to me on my 08 RDX when the temps were below freezing in the single digits and the car was parked outside overnight. The amber brake light stayed on until the temps warmed up above 40 degrees. Acura said it was a failed brake booster sensor and it was replaced for $250 parts/labor. No problems after +2 years; but, temps haven't been that low during since.

It's the tire pressure being low due to the freezing temp. It disappears or should once you drive or when it warms up.

Had the same thing one morning with all my dash lights lit up and the car just barely started in -30 degree celsius weather in Canada. Tire pressure dipped from the normal 210-220 down to 180-190 psi.

The tire pressure low light and the brake light are two different lights. And they are not related with each other. The only thing in common is that they both may (or may not) appear during cold days.
BTW, to prevent the low tire pressure light on you just need to pump more air into your tires when temp. drops below -5 C. It will also improve your car's handling and gas consumption.

P.S. And the lowest temp in the GTA during last 5 years was only -22 C.

Have an 09 base and have gotten a few amber brake system lights over the past few weeks. These have all been momentary lights lasting only a few seconds,. weather has been warm. Over the past 3 days on my way to and from work my dash has lit up like a Christmas tree and the car has what I can describe as a hiccup in power then all is well. These episodes last less than a second then all is back to normal.... any ideas?

Electrical gremlins can be the hardest things to diagnose. I can only suggest checking all connections, maybe starting with the ECU and the instrument cluster (assuming nothing else is happening other than flashing lights in the dash).

I got the amber brake system light on yesterday, and the temp was 80F. I checked brake fluid and it is between min and max. After restarting engine the light went away. I stopped at the dealer to ask, they said it may have been a bubble in the vacuum, and to just monitor it. The break pedal feels normal, and so is the breaking.
Pads are around 50%.

That's a 2007 base RDX, with 110K.

I'm bumping an old thread here, because my wife just got back from our local Honda dealership. I was not there for the consultation unfortunately, but the technician said there was a problem with the Electronic Brake Vacuum Pump and 3 relays that were corroded.

https://cimg8.ibsrv.net/gimg/acurazi...4928122d7c.jpg

https://cimg8.ibsrv.net/gimg/acurazi...fe94d8a45c.jpg
Here is a thread that describes my situation:
https://acurazine.com/forums/1g-rdx-...-p16dd-977678/

Does anyone have any ideas with regards to the location of these relays? I'll have to check under the hood later tonight, but my wife said the technician thought the fuse box was dangling and being exposed to the elements? I'm skeptical as this sounds abnormal, but it could be true.

Also, I wonder if there is a way to diagnose the specific problem with the vacuum pump?

From the receipt you can see the part number they installed.

Searching for that part number on the OEM parts site shows that the relays go under the hood in the engine compartment fuse box.

The service manual most likely guides technicians through a process of checking all electrical components (sensors and solenoids) before vacuum; might be better off inspecting the system with an electrical multi-meter next time it occurs.

https://cimg8.ibsrv.net/gimg/acurazi...d2c300fe43.jpg

Thanks for the feedback. That is actually a quote and not a receipt. The technician did not install anything as I instructed them to do nothing until I had a chance to look myself. I basically just needed them to run a scan of the P16DB and P16DD codes.

And yes, I already ordered a 5-pack of new OEM relays for like 11 bucks and will replace them myself. I should have mentioned that. I was more or less concerned with the technician documenting issues with the pump assembly. Looking at the quote, they didn't diagnose an acutal problem, as it just states "ELECTRONIC BRAKE VACUUM PUMP DIAGNOSES AND REPAIR", so maybe they are just quoting time for what they think it would take to see if there are any issues.

If replacing the relays does not remove the codes, then I will start looking at the pump assembly. Here's to hoping that's all it is!

Let me know if anyone else has any thoughts with this approach.

So I popped the hood tonight after I got home and the under hood fuse box contains 5 black relays. Below are the images of the fuse box and fuse box diagram.
https://cimg2.ibsrv.net/gimg/acurazi...15827a923c.jpg
https://cimg4.ibsrv.net/gimg/acurazi...e68d01fe82.jpg

I'm not sure exactly what function each relay is in control of, but it looks like a few are in control of the A/C, clutch, etc. The set of relays that I ordered came in a pack of 5, so I'll probably just swap out all 5 (4 pin black ones) and see what happens. When I pulled out each relay, they all looked clean with no signs of corrosion. I wish I knew exactly which 3 the technician pulled out during his diagnostic. Again, I wish I was there to ask some of these questions. I don't recall there being another another fuse box besides the small one near the kick panel (This one does not contain any relays from what I can see).

I noticed that these relays don't have a labeled pin diagram either, so I didn't waste my time trying to test each of them.

Check your owners manual for more detailed information.

Hi!
Thanks to the diagram and location details you posted earlier I found the much smaller fuse box next to the battery, the cap flips while remaining connected.

Seemed to me, in my car in the small box, there were three relays in a column, identical?, next to a single fuse and another empty fuse slot. Would match what you were told and the picture of three oxidized relays ... not from the primary fuse box.

Don't have car now, if you need it I can take picture tomorrow morning, just post to let me know to do so.

Theirs two fuse boxes under the hood and one under the dash board. The details are on the lid & in the owners manual. Good luck!

The secondary fuse box is indeed located next to the battery on the driver's side.
https://cimg8.ibsrv.net/gimg/acurazi...3c3203aa96.jpg

https://cimg9.ibsrv.net/gimg/acurazi...189582d360.jpg


Here are a few pictures that show the amount of corrosion on each of the relays.

https://cimg4.ibsrv.net/gimg/acurazi...764dee0646.jpg

I used a few cotton swaps and CRC Electronic Cleaner to clean out the secondary fuse box before installing the new relays. After about 10 minutes, the RDX was back together and operating without any Brake System lights. Wohoo!
https://cimg1.ibsrv.net/gimg/acurazi...c0a18d7928.jpg


The original part number for the relays is 39794-SDA-A03, which is manufactured by OMRON in the USA and is still listed on many OEM Acura websites as the correct relay. The upgraded replacement part number is 39794-SDA-A05 and is manufactured by MITSUBA in Vietnam. I believe this is what many of you are referring to. However, please keep in mind that the "upgraded" relay is only in reference to the sticking A/C clutch. To my knowledge, you should not simply replace all A03s with A05s. Here is a thread that describes the upgrade:

https://acurazine.com/forums/1g-rdx-...pgrade-890420/

In the future, if I have any issues with these relays, I can upgrade to A05s potentially. However, I wanted to follow Acura's current recommendation and for $11 I took the risk.

Glad you worked it out!

I also got an orange brake light over a year ago, thought a brake fluid upgrade to dot4 and refill would fix it. Unfortunately it came back this year so I checked the 3 relays as you reported on the small box, no visible corrosion but did no testing yet.

Yes, thanks to Dcmodels I did the A.C. relay upgrade. Since then I came across report on this site about the radiator fan unit, same relay, similar inductive load, related circuit... and just my feel it's forgetting to turn on at times, so I pay special attention to temperatures and cooling.

Same relay, same circuits, similar symptoms in my second car, civic 2002. At least for that I did find so far the fan switch malfunctioning ...still testing...

Really a relay failure in most of these circuits its not something to take lightly: brake circuit relates to safety, rad. fan relates to engine cooling (blown HG already reported), even A.C. relay could mean very expensive repair bill if not caught in time.

In my case, taken aback at the number of circuits (11 so far) to test in detail before deciding on which relays and how many to buy.