Hombre S Regular Cab 4WD V6-4.3L (1999)
Catalytic Converter: Customer Interest
Emissions - Misfire DTC's/Catalytic Converter Damage
Information IB04-03-S001
Misfire DTCs and Catalytic Converter Damage Due to Installation of Alarm Systems
Issue Date: February 2004
Affected Vehicles
2003 - 2004 and prior Isuzu models.
Service Information
It has been determined that aftermarket alarm systems incorrectly installed in vehicles have the potential to cause misfire codes and damage the catalytic
converter.
These alarm systems use a circuit interrupt which utilize the ignition circuit on the vehicle, they also utilize mechanical relays and normal vehicle
movement can trigger these relays to engage and disengage the ignition circuit while the vehicle is in motion. These disruptions of the ignition circuit,
which occur in milliseconds, may cause more fuel to be commanded. Over time, on and off fuel dumping can cause misfire codes and ultimately damage
the converter assembly.
Engineering could not identify any alarms that utilize solid-state circuitry that would eliminate this concern. Because of this, it has been determined that
all alarm systems must be routed through the starter circuit in order to avoid this condition.
Dealers must be aware of this issue and take note of the wiring on vehicles with alarm systems that come in for repair, particularly for catalytic converter
damage that seem to have no known root cause.
Disclaimer
