I have this persistent C0049 code on my 2013 mustang. The "Service Advancetrac" and Traction Control lights are on as the car thinks it has low brake fluid. Thea abs light is off. Well then I replaced the brake fluid level sensor, checked wirings, tested abs pump in forscan(test passed), brake pads are good, all wheel speed sensors are good, what else should I look. I have been trying day n night to solve this but no luck yet. Help me out please. Local mechanic charged me $200 for diagnosis and told me that I will have to replace abs module and may be instrument cluster module as well. Can'tsspend $750 for that. I'm Very confused.

 

Just wondering, are you running the right (same) size wheels and tires?

 

I don't think it's the cluster. Lamps and message are consistent with a Electronic Stability Control fault.

But you said you are the ABS pump test, which is controlled by the ECU of the electronic stability control as well, and it passed. I'm thinking wiring harness.

P.S. Did you check if ABS works? Can you lock the wheels with a hard brake apply?

 

hmm. You made think of it. thanks. I will try this step as well. I will rotate/replace the wheel just to test. Yes, after the accident the front left wheel was replaced (by the owner) which is of same 17 inches but the thickness is little more. The car is balanced and aligned though. But would it be responsible for the brake light and traction control light?

 

Yes, you are right it shouldn't be a cluster panel module. These mechanics just expect us to replace all modules. Anyways just yesterday I tested abs physically. When I hit the brake hard I could feel brake padel pushing me back (Interminent braking). Also, the abs pump made a sound like 'thaak' just once (is it strange? I thought it should be hydraulic motor like continuously running). Even during abs motor test in OBD (forescan software) it had made the same sound one 'thaakh' and test passed successfully.

 

If the new tire is the same exact size as the old tires, it should not cause the warning lights to go on just because of more tread thickness.

 

hmm right. What should I do now?

 

By the way can anyone tell me how can I diagnose the traction control sensor? I think the trace control module is located on abs pump itself right?

 

Single spin of the pump makes sense. The test checks if the pump can move brake fluid and build pressure. What I was trying to say is that the ESC ECU is probably ok, since the check sends a signal to execute the diagnostic to ESC ECU. Then the ECu has to enter diag mode and execute the check routine.

Also Traction control uses the same wheel speed sensors as ABS. The goal is different though. ABS prevents wheel lock by looking at wheel speeds when on brake (releasing individual wheel pressure when that wheels speed sensor dips below the reference speed of other wheels), while TCS prevents wheel spin while on throttle (by applying brake pressure to the wheels that go above the reference speed). They both use the pressure sensor located in the ESC module, but can also function without it If that pressure sensor was bad you'd get a specific CEL though.

Wait, just noticed something. Your stability and traction lights are on, but not ABS. This means ABS and EBD (electronic brake force distribution) are still active, but traction and stability control are not. That points to Lateral Acceleration or Yaw Rate sensor. Those are not used by ABS, but they are by stability and traction control to a point. But you should be able to read the codes in the ESC system to tell. On these cars there is one sensor, and it provides Longitudinal and Lateral accelerations as well as Yaw Rate over CAN. The problem is I'm not sure it it's an external sensor, or one mounter in the Air Bag unit. Air bags have quite a few accelerometers, and in some vehicles those are used for stability control.

 

The yaw sensor gives out some reading. So most probably it is working. I didn't see lateral sensor. But that's good point out. I'll try fetching it in obd tomorrow. If fact I'll make a full video of what exactly is the issue and I'll also show obd readings that I'm getting. And thanks for explaining abs vs tcs in detail. I'm pretty sure abs is working fine as I've physically tested it as well. I'm getting delivery of my fluid level sensor in 2 days. So finger crossed if that's the main culprit (but I've tested bypassing the sensor and it didn't work either) so most probably it is not the reason and sensor is fine.
I doubt airbag has anything to do with it. So I am waiting till may end to solve this brake light issue. Else I'll just replace the airbags to see if it goes away and will sell it with loss. Sad ending but the truth

 

Good luck man. Chasing down these electrical gremlins is a pain. I think if you can read the codes directly from the ESC unit will help narrow down the search, but it could be something as simple as a loose wire in a connector.

 

Monster said that some of the sensors could be in the air bag. You said that the car had been crashed. Did the replace the airbag ??????? mmmm
I have been fighting some strange electrical issues myself and finally solved it this morning.
https://themustangsource.com/forums/...e-help-547620/
Just keep digging and I am sure that you will figure it out. Ford does have a history of gage cluster issues. I have had the one in my Explorer fixed twice by this company.
They do a great job with very reasonable pricing and fast turn around.
https://rtgrim.com/