Intialization of the background test is the first one carried out in the system.
It therefore stsrts in the internal ROM and leads to supervisor identification by testing and initializing the external bus and testing the internal RAM.
Afterwards the external RAM is tested and the checksum of the EPROM is calculated.
After starting, A/D converter with all electric connections are monitored continuously by the ECM.
A checksum is the total of all ones in a string of data.
By comparing the checksum value with a stored value, a malfunction can be detected.
If the ECM A/D converter generates threshold value, the ECM judged this as a fault and DTC is set.
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● Rationality check | ● Faulty ECM |
Enable Conditions | ● Ignition on | |
Threshold Value | ● Case 1: dynamic RAM test failure ● Case 2: APS 2 signal is above 200.39 mV when checking the ground connection every 2 second ● Case 3: sensor supply voltage is above 5.16 V or below 4.7 V | |
Diagnostic Time | ● Case 1: 0.1 sec. ● Case 2: 0.5 sec. ● Case 3: 0.1 sec. | |
MIL Fuel Limit Fuel Cut EGR Off | ● No ● Yes ● No ● No | |
Fail Safe | ● Engine speed is fixed at 1200 rpm without the accel position sensor action |
