Code 19
THROTTLE POSITION SENSOR AND MASS AIR FLOW SENSOR - DTC 19 (LOW THROTTLE POS. VOLTAGE; HIGH AIR FLOW VOLTAGE)
The ECM looks for a combination of throttle position signal voltage and mass air flow sensor load signal voltage that cannot occur in a correctly operating system.
The throttle position sensor signal voltage (EMS track) normally varies between 0.6 volt at idle to 4.5 volts at full throttle. The mass air flow sensor load signal voltage normally varies between 1 and 4 volts; the higher the voltage, the higher the load.
The ECM will flag DTC 19 if the throttle position signal voltage is at the "adapted idle" value and the engine speed greater than 1000 rpm when MAPS signal indicates a high load.
Normal Signal MAFS Versus Engine Speed Load Site 12:
Conditions Required For DTC 19 Flagging:
Throttle position sensor voltage signal to ECM - On idle.
Engine load site - Load site 13 or higher.
Engine speed - Greater than 1000 rpm.
Response time - 5 engine revolutions.
Limp Home Default
If DTC 19 is flagged, the air flow signal is accepted as accurate. The throttle position voltage defaults to more than idle (1.5 volts) so that idle functions are disabled.
Possible Faults
- High resistance connection to ECM, MAPS or TPS
- Water in MAFS
- Short circuit or open circuit wiring from the ECM to the mass air flow sensor
- Short circuit or open circuit wiring from the ECM to the throttle position sensor
- Defective throttle position sensor
Diagnostic Notes
1. The throttle position sensor and mass air flow sensor signal voltages can be monitored and intermittent faults captured using the PDU "Datalogger" function.
MAFS Test 1: Engine Load - Idle
- Run the engine at normal idle speed; normal operating temperature; select NEUTRAL; air conditioning OFF.
- Use an approved DVOM or monitor the PDU MAP signal to measure the mass air flow sensor signal voltage at the ECM. Use only an approved DVOM to measure the mass air flow sensor signal voltage at the MAPS.
- Back probe the connector pin as directed on the diagnostic flow chart.
- The typical voltage measured should be 1.20-1.50 volts.
Circuit Diagram
Circuit Diagram:
Flow Chart: DTC 19
}��Flow Chart: DTC 19:
