Diagnostic trouble code (DTC) information

Condition 

ECM-8400 is stored if one of the 5 volt supplies is short-circuited to supply voltage or ground or if there is an open-circuit in the circuit and the control module interprets it as a fault.

Substitute Value 

None.

Possible Source 

Signal too high: 

• short-circuit to supply voltage in the signal cable
• open-circuit in the signal cable.

Signal too low: 

• short-circuit to ground in the signal cable.

Fault symptom[s] 

• poor performance
• uneven idle.