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Brake Warning Light - Red


Ron Walker
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I had a brake line replaced and brake fluid added. Now the red warning light in the instrument panel remains lit. The CRT gives a warning of Lo Brake Fluid and the ECM code E171 cannot be cleared. I tried clearing the codes via the CRT and also tried disconnecting the battery and the code warning doesn't clear and the red warning light remains lit. I thought I read that someone else had this problem, but I searched the Forum and came up empty. I may have missed something. However, I would like to clear the code and eliminate the constant red warning light. Prior to the leaking brake line and resultant loss of brake fluid, there was no code and no red warning light. Any one else have this issue, and if so, how was it corrected? BTW, the amber ABS light lights up at start up and goes out after the 30 second warm up.

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9 minutes ago, Ron Walker said:

the ECM code E171 cannot be cleared.

I'm not familiar with that code Ron. what is it?

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The diagnostic booklet shows ECM Input E171 as "Brake Switch." But the CRT warns of "Lo Brake Fluid." 

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I am probably over my head here, and am not familiar with the diagnostic booklet, but the ECM generally has nothing to do with the brake system, which I think is the ECBM? I believe the BCM has inputs for brake fluid level and pressure. 

 

Check the brake pump pressure switch plug for fluid contamination.

Edited by 2seater
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47 minutes ago, Ron Walker said:

The diagnostic booklet shows ECM Input E171 as "Brake Switch." But the CRT warns of "Lo Brake Fluid." 

Sorry, I misunderstood. I was thinking code, not input. I think the red light is telling you the parking brake is on but that doesn't explain the warning on the CRT. Have you held the parking brake release while pulling up on the pedal to see if the light will go off?

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No I'm wrong about the parking brake being the problem. That would be a BCM input code.

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2 hours ago, 2seater said:

Check the brake pump pressure switch plug for fluid contamination.

Can you give me a hint on where that switch plug is located and what I'd be looking for?

 

1 hour ago, Ronnie said:

Have you held the parking brake release while pulling up on the pedal to see if the light will go off?

I'll check the parking brake anyway. I told the mechanic who worked on my car specifically to not engage the parking brake because the cable, unfortunately, is corroded and would "stick" and not release. The mechanic wisely said that he never engages the emergency brake on customers cars unless he is aware that corrosion situation would not prevail.

 

Also, I'll run through the diagnostics and warning notices again to make sure I can report specifics. 

 

Thanks for the tips.  

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7 hours ago, Ron Walker said:

Can you give me a hint on where that switch plug is located and what I'd be looking for?

 

 

It looks like Rogold is on the ball and provided a picture of the location. You are just looking for moisture, which will be brake fluid, inside the electrical connection. The pressure switch not only controls the start and stop of the brake pump it also contains switches for the warning lights. It is generally very reliable so this is just to cover a slight possibility.

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2seater and Rogold sent me in the right direction for the brake pressure switch - thanks. Mine (in photo below) looks a bit different (an '89 model) but I think I found the large nut the ROJ article referenced.  See first photo below, bottom right in photo. Photo 2 just a shot of under-hood. Photo 3 shows the CRT warning.  All the connections seemed uncontaminated with brake fluid and are dry. I removed and inspected the sensor connection immediately below the brake fluid reservoir, but none other. The connection points were dry.  IMG_20220728_130125176_HDR.thumb.jpg.633c64a459b21779e7a4bb0f3e6e9741.jpgIMG_20220728_130159695_HDR.thumb.jpg.7f5d5a63075db448aaf78d3907a872b5.jpgIMG_20220728_130456504_HDR.thumb.jpg.0708c5d6131e44ca8796b876c25a3def.jpg

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I've never saw that warning on the CRT before. It's cool how it even shows you where the reservoir is located in the graphic.

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I also tried the emergency brake release while pulling up on the pedal. It was unmovable, and as Ronnie stated, it wouldn't have been an issue anyway. 

 

I probably confused everyone with the ECM input (E171) (sorry, the E171 input message was Lo Brake so that's what I surmised dealt with the CRT message of Brake Fluid Low) since the Diagnostic Codes I checked today gave me only current and history for Cam Sensor Circuit (E041) and Cruise (B671). I did resets for the BCM and got the message - "Codes Not Clear." I did resets for the CRT and ECM and both messages were "Codes Clear."  However, I checked after reset, and still got E041 Current and History, and B671 Current. Neither of these have anything to do with the brakes or the red brake warning light. 

 

I'm still stuck. 

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The CRT is saying the fluid level is low in the reservoir. There is a float switch in the reservoir that must be telling the computer the fluid is low. I can't see if the fluid is up to the full mark or not. Maybe it's because the fluid is new and clear. Is it up to the full mark after pumping the brake pedal about 25 times with the key off?

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The pressure switch is that vaguely green cylindrical item directly below the accumulator. The fluid level looks perfect if that is with the system pressure pumped all the way down. If that is with the system pressurized, it is too high, but it certainly isn't low🤨 Your underhood pics look super tidy.👍

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Maybe look inside the fluid reservoir and see if the fluid level sensor/ float is stuck or dirty. Maybe the mechanic stuck a tube down in the reservoir to pull out old fluid and jammed it up. Just guessing 😉

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To be clear you have to remove the brake pressure switch and look at the electrical contacts at the screwed in end to look for moisture.

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My problem has been solved thanks to Rogold's suggestion. Bear with me for the following explanation.

 

The photo in the previous post showed the brake reservoir after I pumped the brakes 25 times with the key on and engine running. That photo shows the fluid level right on the full mark. Following Ronnie's comments, I again pumped the brakes 25 times with the key off.  The fluid level rose to the top of the reservoir. I did the pumping method 2 or 3 times since the recent repair, and each time I evacuated an excess amount of brake fluid from the reservoir. (I told the mechanic not to overfill and to use the pumping method - he says he followed my instructions.) However, I suctioned the excess fluid from the reservoir.  The current level is as is seen in the photo below - probably in inch or so below the full mark.  In the photo is also the the  IMG_20220728_183937557_HDR.thumb.jpg.ee591109a17d39b0d196f45e44d23fd1.jpgIMG_20220728_183658951_HDR.thumb.jpg.684b67af5f58eab9996e094b938f9497.jpgbottle used to contain the excess fluid - a combined 7 1/2 ounces. I suctioned 2-3 ounces of excess fluid each time I used the pumping method down to the full mark so as not to be overfilled. 

 

The other photo is looking straight down into the fluid reservoir. The circular object surrounded by a black ring apparently is the float mentioned by Rogold. I used a flashlight and a drinking straw to probe the float in an up and down motion. The probing dislodged the shiny object propped up in front of the bottle with the excess fluid contained therein. It looks like a piece of aluminum foil that covers the opening of a new can of brake fluid. Removing the aluminum foil, and starting the engine, the ABS yellow and the Red Warning light both disappeared! Problem solved!  Thanks to all for your help!

 

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Haha, you should tell your mechanic about that!  Glad you found the problem!

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