Diagnostic trouble code (DTC) information

Condition 

Diagnostic trouble code (DTC) ECM-78 is stored if there is no signal from the engine speed (RPM) sensor to the control module (signal missing) or if the control module detects an abnormal signal (faulty signal).

Substitute Value 

• No camshaft diagnostics
• No camshaft control
• Ignition retardation
• No boost pressure diagnostics
• No heated oxygen sensor (HO2S) diagnostics.

Possible Source 

Signal missing: 

• Open-circuit in the signal cable
• Short-circuit to ground in the signal cable
• Short-circuit to supply voltage in the signal cable
• Faulty engine speed (RPM) sensor.

Faulty signal: 

• Loose connections
• Damaged flywheel
• Faulty engine speed (RPM) sensor.

Fault symptom[s] 

• The engine misfires
• Malfunction indicator lamp (MIL) lit.