Diagnostic trouble code (DTC) information

Condition 

If the engine control module (ECM) does not receive a signal from the engine speed (RPM) sensor (signal missing), or if the control module counts more than two teeth too many or too few on the flywheel during one revolution (faulty signal): The control module interprets it as a fault and diagnostic trouble code (DTC) ECM-78 is stored.

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] 

• Malfunction indicator lamp (MIL) lit.