Sometimes a code will lead you down the wrong path, especially when the underlying symptoms seem unrelated. Follow this Real Fix to see how a stalling Buick Regal with a traction control module code was diagnosed and the component that caused the problem.
Vehicle
2004 Buick Regal LS 3.8L
Title
U1040, Replaced Ignition Switch
Complaint
The customer states the vehicle is stalling and instrument lights are flashing.
Cause
Connected a scan tool and found code U1040 – Lost Communications with Electronic Brake Traction Control Module (EBTCM). Attempted to communicate with the anti-lock brake traction control module using the scan tool and found communication was not possible. Disconnected the anti-lock brake traction control module connector, visually inspected the connector and terminals and wiring harness and found no apparent faults. Reconnected the EBTCM, key on, back-probed the connector with a multi-meter to check for the presence of voltage and ground at the anti-lock brake traction control module and found the specified 12 Volt supply was less than 12 Volts. Used the multi-meter to back-probe the fuse for the EBTCM and found the specified 12 Volts was below specifications. With the key on, engine off, used the multi-meter to back-probe the ignition switch connector and found multiple output terminals were below the specified 12 Volt supply. These test results verified the ignition switch was faulty.
Correction
Replaced the ignition switch, cleared codes, performed a road test and verified the vehicle operated properly. The check engine light did not illuminate and no fault codes returned.