Finding what is draining the battery can be tricky, but sometimes your ears will help you find the culprit. One Mitchell 1 SureTrack community member found this with a 2007 Chevrolet Impala LT 3.5L. The customer had complained the battery went dead while the vehicle was sitting. After performing tests with no luck, the technician turned to a fellow community member. Let’s take a look.
The Diagnosis
Initially, the technician started with a charging system test, which appeared normal. Then, while looking for loose wiring, he stumbled upon an odd clicking noise that seemed to be moving throughout the dash. The tech also found the temperature control doors were also clicking. They were attempting to move, but were in fact stuck to one extreme.
After hearing this, he scanned the HVAC system. It was showing 3 different codes: B0223 Recirculate Position Command Circuit Actuator Stuck; B0408 Left Air Mix Control Circuit Malfunction Actuator Stuck; and B0418 Temperature Control 2 Circuit Actuator stuck. Still struggling to find a solution, the technician turned to his SureTrack community members for advice.
Thankfully, one fellow member suggested commanding the motors with the scanner: “When the motors have reached the end of their travel, the module should see the increase in amperage and turn the motors off. With the plastic worm gear worn off there is not enough load to raise the amperage so they continue to run. You can replace just the one that is ticking then reevaluate; it’s not abnormal for them to set a code and still work fine.”
The Fix
From this deductive process, the tech determined that internal failure of the controller caused the motors to run with the key removed and drained the battery. In response, the tech replaced the HVAC control module and three bad mode door actuators which solved the problem and got the customer charged up and back on the road.
Real Fixes from Mitchell 1’s SureTrack® expert information resource are documented issues from actual shop repair orders and community discussions. Read the Real Fix in the Mitchell 1 ShopConnection Blog.
