Brake warning light came on, due to a leak in rear master to ABS module rusted line. Replace that & red BRAKE & yellow ABS lights stay on. NOTE, had to move TIPM & wiring to get access. Pedal fades still, Replace master twice as code C1009 points to a faulty level sensor, 3rd master RAYBESTOS works fine still C1009 ( brake fluid at all times full ) , Replace seeping RR wheel cylinder, bleed all brakes again, brakes work perfect. Even plug in original, that still gives C1009 ( brake fluid level false code with full master ) A very conflicting amount of info out there = some say fluid level sensor should be 10,000. ohms & yet DODGE says it should be 1,000. ohms = ??? Mine tests 9.7 @ 200k ohms setting, so i interpret that as 9,700. ohms = is that correct ? I have ordered a 1,000. ohm resistor to test soon. The 10k ohm resistor i tried earlier had no effect. Replaced 2 ABS Modules to no effect, so put original back. Replace TIPM & Front Module still false code C1009, leave TIPM reinstall original Front Module. Just to rule out backfeeding somehow, new left front & rear diff speed sensors, no affect. Voltages at level sensor are Good ground, 5.1 volts signal. Cleaned left fender main ground but was spottless already. My theory since no wire defects visible, and the power & grounds that i do have very limited schematics for test good, is that a transistor is stuck on sending request to warning light, when it should have opened. That may be ruled out by todays cluster replacement that had no effect. Also a PCM expert said they do not believe the PCM is involved in this circuit. Resistance level sense signal to ground is 9.0 ohms, shows good. techCONNECT diagnostic tree says REPLACE ABS MODULE, = however this also seems incorrect ? If this is such a rare issue that no solves are listed online, then odds are my ABS module is ok = but is it. WIRES were stressed somewhat with the mammoth plastic brackets that must be moved to access the ABS block, so there COULD have been damage to a wire, visual gave no indication other than a scraped tan wire that only casing was thru & i taped that. Without FULL color & expected voltages or ohms SCHEMATIC, i am unable to continue testing. As a last resort, it went to my local DODGE DEALER to be looked at by their TOP diagnostic guy, and despite telling them all that i have written here, the tech never looked at the info & tells me it looks like a fluid level sensor = wow i expected more intelligence, just WOW. I contacted another dealer that may look at it if i cant get this solved, and says they may be able to pass NYSI even with the red BRAKE warning light on = is this

Float Plugged in

BRAKE & ABS Lights ON

1K Resistor Connected

SOLVED !!!
accurate ? I am not going to give up on solving this = my family is depending on me. This requires some very experienced diagnostic minds to get to the ROOT CAUSE of this so far unsolved mystery false C1009 code . 2008 Dodge Dakota SLT crew cab, 4.7, 5-speed auto, 4x4, RWABS = Rear wheel ABS only Vin # 1D7HW48NX8S571199 188 views so far in the 11 days UPDATE JULY 19 2022 SOLVED = i just got the 1K OHM RESISTORS i had ordered to confirm correct signal at master cylinder float level sensor. As soon as the 1,000. ohm resistor was connected and i turned the key = NO MORE FALSE BRAKE WARNING LIGHT & ABS LIGHT ANYMORE !!! So anyone who replaces a master cylinder and gets these sudden lights, there may be a DEFECTIVE FLOAT SENSOR that is rated at 10K OHMS instead of the 1K OHMS that the circuit is looking for. This cost me 8 months, a massive amount of diagnosis & full auto on my parts cannon, which cost me many hundreds of dollars along with hundreds of hours trying to believe that 3 different master cylinders from 2 different manufacturers could not possibly be defective BUT yes all 3 were calibrated to 10K OHMS when the dakota communication system was looking for 1k ohms. In the beginning i saw conflicting numbers online saying it should be 10k , but i verified thu buying Mitchell eauto repair for a year and they show 1K OHMS for the float level sensor & they were correct. Hopefully this helps others out there that refuse to give up & are determined to solve their vehicle dysfunctions !!!

 

Wow, you definitely nailed it!!! I'm having the exact same problem after replacing the brakes in my 2008. the previous owner had replaced the master Cylinder with an aftermarket one with the "brown" sensor. I'm getting both the ABS and red brake light constantly on. The scanner only pulls the code "brake fluid level low" from the truck. I just ordered a brand new genuine Mopar master cylinder with the black sensor and see if that cures the problem before going the resistor route.

 

Hey, im glad i was able to help you and others. That is why i posted all my diagnostics and SOLUTION to this shamefull defect in brand new products that i am sure many others have scrapped their trucks due to not realizing what was going on. The last thing anyone would ever suspect is many different brands parts to be manufactured to incorrect specs but this proved that is reality here. My dakota has been issue free ever since i installed the correct resistance resistor in the brake fluid level circuit. After over half a year and every thing i and dealers could think of, my dakota almost became an unuseable parts heap, but perseverance paid off in the end, and it passed new york state inspection and could be driven on the road finally again. I also had to modify my front cam bearing on my 2011 jeep hemi engine due to the brand new cam front journal was machined too large, completely out of spec. Since the warranty was expired due to length of time from purchase to actual install and discovery of bad machining, i chose the only realistic solution to save the project. Parts these days are lacking basic intelligence in both not following manufacturers specifications and lack of follow up quality control.

 

Now let me ask you a very important question: You stated that you replaced the master cylinder 3 times. Were any of the ones you replaced a genuine Mopar one? You mentioned Ratbestos, but not the other manufacturer.

As I stated earlier, I ordered a genuine Mopar master cylinder and plan to get it installed next week. I’m not a tech., so I have to pay to get it installed. But then if this doesn’t cure the brake lights on continuously, I’ll take the truck to an auto electric shop to get the resistors installed.
I might need more information later on the specifics of the resistors and where to get them, so might contact you next week if the brake lights are still on even with the new original master cylinder.

 

All of the 3 master cylinders i bought were aftermarket. First 2 NAPA and last 1 thru rockauto Both suppliers have completely non functional customer service and simply do not care about this issue. The actual Mopar master cylinders should work because they are manufactured to Dodge specs, but i guess we will find out as soon as yours is installed. After all the incompetence that caused the aftermarket mistakes may extend into whoever makes them for Mopar. As for the resistor, it should be a high quality one that is as close to 1000 ohms as possible. The resistor that i used was ordered thru walmart and is a ( 50W 1K Ohm wire wound chassis mount aluminum housing power resistor ). What i did after finding this as the solution, was to leave the plug intact for a possible future correctly manufactured master cylinder to be installed, and pulled back insulation to carefully and securely wrap wires going to resistor, and sealed all 4 connections with permatex silicone, and to glue it to the body of my dakota in a place that could be well seen so it is obvious to any future owner that this modification was made. After the extensive ordeal i went thru in diagnosing the actual cause of this issue, i was far too tapped out financially to afford an authentic Mopar master cylinder, and i am left happy that at least i solved it and can drive my inspected truck as that is the main thing here.

 

Thanks so much for your quick reply.

Will keep you posted as soon as the new master cylinder is in!

 

I have since ordered a new Mopar master cylinder.

One further question. Upon reading again your post, you stated that at one point, you had switched back the original master cylinder, filled it with fluid and still tripped the lights.
Strange though...can't explain that.

 

I was perplexed about that as well, however being as this is not a set ohms but a variable resistance sensor, it must be affected by the surrounding ground effect when it is bolted on. Have you not yet had the new MOPAR master installed ? Make sure like me that you post here after it is solved so others see if that was the better resolution to this bad parts issue.

 

Hello:

Just wanted to provide an update into this.
I since ordered a new genuine Mopar master cylinder in order to replace the one in my truck that was tripping the ABS and Brake lights with a code of "low brake fluid". it turns out that indeed the sensor in the master cylinder was the problem. Once the Mopar one was installed, the lights cleared out and everything works as it should.

Many thanks for this guidance and again wanted to clarify that if you replace the master cylinder with an aftermarket one, it will most likely than not trigger the abs and brake lights, as it seems like these trucks do not like aftermarket sensors. The two solutions are either installing resistors as stating in this thread, or install a Mopar one.

 

Always helpfull to everyone here when there are solves posted so that those who just had this issue may be guided to a real solution to what would otherwise have been a nightmare as it was for me...