Diagnostic Aids

Tech 1 has the ability to command the cooling fan and A/C clutch relays on and off and command stepper cruise enabled or disabled. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connections or damaged harness.

Perform intermittent check by monitoring circuit and code status while wiggling related wiring and connectors. If failure is induced, monitored circuit status will change rapidly and/or related code will set.

Fig 1: Code 28 Schematic (2.2L) Quad-Driver No. 2 Error

Fig 2: Code 28 Diagnostic Flow Chart (2.2L) Quad-Driver No. 2 Error