Problem: The owner brought his Sunfire to
the shop because the exterior lights were dim, and the windshield
wipers ran slow, even when the high-speed setting was selected.
Details: The first thing the technician did
was to check the charging system. The alternator output was 14
volts with loads, such as lights, wipers and defrosters
operating. Next, he connected a scan tool to check the body
control module’s (BCM) charging system parameter identification
data (PID). It was reading only 11.5 volts with the same loads
on. The next step was to call ALLDATA Tech-Assist for some
After reviewing the wiring diagrams, the Tech-Assist consultant
found that ground point (G102) is used for the exterior lighting,
the wiper motor and the BCM. The consultant suggested that the
technician inspect the ground splice at that location.
Upon inspection, the technician found that G102 was corroded and
the battery tray bracket it attached to was rusty and cracked.
The technician performed a voltage-drop test from the negative
battery cable to G102. There was a 2 volt drop.
Confirmed Repair: The technician repaired
the bracket and the ground connection. After the repairs, there
was no significant voltage drop, the lights were bright, and the
wipers moved at the correct speeds. Fixed!