LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Chevrolet >> 1995 >> Corvette Base, 2D Convertible, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> ECM/Pcm Code Charts >> Code 78, Secondary Cooling Fan Driver >> Test Description
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Test Description

NOTE: Test numbers refer to numbers on diagnostic chart.
  1. Even if the fan does not operate, listen for an audible click from relay.
  2. This check can detect a partially shorted coil which would cause excessive current flow. Excessive current flow to a QDM will be detected as a fault and set a code.
  3. The remaining checks will identify a circuit problem that has caused an excessive current flow or inoperative relay.
Fig 1: Code 78 Schematic (Corvette) Secondary Cooling Fan Driver
G95E14336
Fig 2: Code 78 Diagnostic Flow Chart (Corvette) Secondary Cooling Fan Driver
G95F14337