Cause Of Brake System Warning Light Remaining On After Disengaging Parking Brake?

[The Swamp Fox]

One last update for sake of future reference by any poor souls who find themselves in a similar predicament.

I first purchased a replacement dash clock / secondary information center to replace my unit with the missing ABS light. This was a stupidly difficult process, as three different units from eBay all proved defective in one way or another. If you go this route, be sure to buy only those with a money back guarantee and free return shipping, as I did. I ended up finding a working unit from my local pick-a-part.

After installing, I verified that my ABS warning light was in fact on. This meant that there should be an ABS system-related code stored in the ABS module. I ended up purchasing the OTC Tools 3208 OBD-II scanner which doubles as an ABS code reader for certain models, including the Aveo.

The scanner was capable of reading ABS module codes that my normal OBD-II scanners (ScanGaugeE & Kiwi 3) could not. The initial scan came back with 8(!!!) ABS-related codes:

1. C1200 — Left Front Wheel Speed Sensor Circuit Open or Shorted
2. C1201 — Left Front Wheel Speed Circuit Range / Performance
3. C1202 — Left Front Wheel Speed Sensor Input Signal Equals Zero
4. C1203 — Right Front Wheel Speed Sensor Circuit Open or Shorted
5. C1206 — Left Rear Wheel Speed Sensor Circuit Open or Shorted
6. C1207 — Left Rear Wheel Speed Sensor Circuit Range Performance
7. C1208 — Left Rear Wheel Speed Sensor Input Signal Equals Zero
8. C1209 — Right Rear Wheel Speed Sensor Circuit Open or Shorted

I cleared all of these codes, ran the car for a bit, then re-scanned and found that only C1200, C1203, C1206, and C1209 had reset. All of these were related to the ABS wheel speed sensors, which pointed me in the right direction in the troubleshooting workflow.

I checked all of the ABS wheel speed sensor wiring for obvious damage or shorts, and found none. I then disconnected the ABS sensors at each wheel and tested their resistance with my multi-meter. The service manual says they should spec out between 800–1,600 Ohms. I pulled the below readings:

• DF — Infinite resistance (open loop)
• PF — 12.8 million Ohms
• DR — 300,000 Ohms
• PR — 2,450 Ohms

All of these were obviously out of spec, so I ended up ordering four replacements for around $50 total from Rock Auto. The replacement isn't complicated by design, but my old sensors were solidly stuck in place. I had to end up burning them out with a propane torch and picking out the remnants with a pick. Took the better part of an afternoon.

After replacement was completed and I had re-cleared the ABS codes once more, the codes have yet to return. It appears my problem is solved. Finally!