Ok, well maybe not the fix OF the century but a fix for a Buick Century. Follow this Real Fix to see how a code 26 for the Quad Driver Circuit was diagnosed and repaired on this 1990 Century.
Vehicle
1990 Buick Century Custom 3.3L
Title
Code 26, Replaced Powertrain Control Module
Complaint
The customer states the check engine light is on.
Cause
Connected a scan tool and found code 26 – Quad Driver Circuit. With the key on, engine off, connected a fused jumper between the diagnostic link connector terminals A and B, observed the evaporative emission (EVAP) purge solenoid, the low speed engine cooling fan relay and the torque converter clutch solenoid, and found there was no audible click heard from the EVAP purge solenoid. Connected a test light across the EVAP purge solenoid connector terminals and found the test light illuminated. Disconnected the fused jumper from the diagnostic link connector and found the test light was still illuminated. The test light should have been off. Disconnected the powertrain control module and found the test light was no longer illuminated. These test results verified the powertrain control module was faulty.
Correction
Replaced the powertrain control module, cleared codes, performed a road test and verified the vehicle operated properly.
SureTrack® is a powerful value-added feature available with select Snap-on diagnostics tools. It offers an exclusive combination of expert knowledge and detailed parts replacement records, all wrapped in an interactive community.
Want more? Click here for more information on using SureTrack.
Looking for diagnostic tools? Click here to request more information on Snap-on diagnostic tools.
New or Expired SureTrack users: Click here for authorization key instructions.
