Speedo erratic behavior, ABS & Brake light on
 

Hey guys, I am new to the forums here, but I couldn't find very helpful information with this issue that recently arose.


About three days ago, while I was driving home, the brake and ABS light turned on and the speedometer began to go up and down as I would accelerate. The Brake and ABS light turn on and off as I am driving. When I first turn on the car, the Brake and ABS light are off, but as soon as I begin moving, the issues commence. Previously, I had issues with the ground cable oxidizing and losing connection at the terminal due to the oxidation. Can it be a problem with the ground?


How do I go about trouble shooting these problems? It is a 2007 scion tc btw.


Thanks guys and gals

Troubleshooting these types of issue can be difficult, but the types of issues you describe generally suggest and electrical issue. Main area to look is the alternator, including all it's connections. You may be able to have your alternator tested at a shop. You can also monitor the battery voltage through the obd port with a scanner, but I don't know if that would be sensitive enough to detect an issue.

How do I go about trouble shooting these problems? It is a 2007 scion tc

Have auto zone or someone with a carscanner pull up the abs on it. Sounds kinda like my issue but your leans towards abs sensor going bad possibly

Same issue
 

I'm running into kinda the same issue. Except my speedo isn't working at all. The abs and brake light get are on. Since the speedo isn't telling me how fast in going, the odo isn't keeping track of how many miles are on the car. It's been stuck at 152059 since yesterday morning. And this all started after my car sat in my driveway over night while it poured outside then I got into it in the morning and started it. Water must have gotten inside somewhere. Any ideas?

Thx

The things I posted above are what you need to check. It's an electrical issue and there is no way to know without diagnosing and systematically eliminating each potential cause. My money is on an alternator or alternator connection issue. These are the classic symptoms.

Was it raining when you had these issues?