Component Location
General Description
Driver's intension to accelerate is transmitted to ECM through Accelerator Pedal Sensor(APS) . And APS, whose mechanism is same as TPS, is required for ECM to determine optimum fuel injection quantity.
As fidelity of APS is strongly required, APS is devided into two. One is APS1, which outputs main signals and the other is APS2, which monitors APS1 performance.
APS1 and 2 do not share power supply and ground. Normally, APS2 output voltage is the half of APS1 and if the ratio of two signal is out of specified value, error is recognized then, Limp Home mode is activated.
When Limp Home mode is activated, engine speed is fixed at 1200RPM and driving performance is limited to prevent excessive power generation due to APS false signal.
DTC Description
P2128 is set when output voltage of APS 2 is above the maximum value of 2470 mV for more than 0.25 sec. This code is due to the short to battery in APS 2 power circuit and signal circuit or open in sensor ground circuit.
DTC Detecting Condition
Item | Detecting Condition | Possible Cause |
DTC Strategy | Voltage Monitoring
| APS 2 Circuit
APS component
|
Enable Conditions | IG KEY "ON"
|
Threshold Value | When output signal is above the maximum value (above 2470mV)
|
Diagnostic Time | 250ms
|
Fail Safe | Fuel Cut | NO | |
EGR Off | NO |
Fuel Limit | YES |
MIL | YES |
Specification
| Pedal released | Pedal depressed | Sensor Type |
APS 1 | 0.7V~0.8V | 3.8V~4.4V | Variable resistance type (Potentiometer) |
APS 2 | 0.275V~0.475V | 1.75V~2.35V |
Diagnostic Circuit Diagram
Signal Waveform
Fig.1) APS 1 and APS 2 signals are measured simultaneously, Check if output value is rising and APS 2 is 1/2 of APS 1 signal.
noteAPS 2 Ground checking signal is for ECM to monitor APS 2. This signal drops APS 2 output voltage to below 200.39mV per 200msec. If APS 2 output voltage does not drop to below 200.39mV, ECM sets DTC as recognizing ground circuit error of APS 2.
? The waveform below 200.39mV is not detectable in Ground checking signal waveform of APS 2 signal. Instead, the waveform which drops a little is detected. If APS 2 data of "SERVICE DATA" on the Scantool varies from 350mV to 0mV periodically, it means it works well.