Q: ABS and brake light is on

If the ABS warning light is on, that means that there are downloadable ABS diagnostic trouble codes, much like the codes you would download if you have a Check Engine Light diagnostic. The ABS trouble codes will give a general indication of "where" the trouble lies but as far as what part(s), if any, that would need to be replaced, that would depend on what the component level diagnostics and testing reveals. So, just to give you a for instance, you could have a trouble code that basically states: "lost signal from LF wheel sensor" or "LF wheel sensor out of range". Those codes could mean the left front wheel sensor is bad, in which case you need a wheel sensor but the codes could alternatively mean that the harness connection (terminals) between the sensor and the vehicle wiring are loose, corroded, or damaged, that is the sensor is OK, there just is a poor, or no, connection. So, to answer your question as to cost, it just depends on exactly why the code(s) have set and that can only be determined as the individual component(s) referred to in the codes are individually tested. In the just cited example, the sensor is testable because the sensor creates an output that can be measured on a scope. If the sensor tests OK, then the wiring is looked at and so forth, on up to the ABS control unit. One of the biggest misunderstandings of these modern day "diagnostic trouble codes" is that you can read a code, identify a part and just go out buy the part and replace it. You can’t unless you don’t mind wasting money. All parts, or systems, "suspected" to be faulty, by virtue of a code "referral", have to be INDIVIDUALLY tested and if you have chosen a good mechanic, the mechanic will tell you conclusively and authoritatively which part is bad, and why, because he or she will have conducted an actual diagnostic. YourMechanic can dispatch a professional to interpret the ABS Codes that have set and begin the process of tracking down the fault to get to the root cause. At that point, of course, you will get an estimate of the exact cost to repair the issue. Hope we can help you get your issue resolved and if you have additional concerns relative to this, by all means let us know.