DTC logic

SAE - Society of Automotive Engineers

0x96A123 ---Consider as sample dtc

Examples:

DTC_0x96A123

DTC_0x96A223

DTC_0x96A323

split the byte as,

DTC_0x96A1 -----23

Search in the DTC database as,

96A1

After search you can find out like ,

P16A1 or C16A1 or B16A1 or U16A1

P-00-powertrain

C-01-chassis

B-10-body

U-11-network

here,

96A1

9=1001

where

10 -is body and 01 is OEM Specific.

B16A1 -SAE Format

0x96A1 -Hex Format

what is nibble ?

4-bits

lower nibble /upper nibble:

10 01                01 10

if  DTC Status is not considered then length is  2 byte only ( mostly not considered)

B1 6  A1 23

B-10

1-01

6- 0110

B16 - 1st byte

A1 -10100001-2nd byte

where A1 is Failure type  or Fault type byte.

last byte 23(0010 0011) is status mask,

note-reading data as

byte-left to right

bit-right to left

bit 0 -1-Test Failed-fault is active.

bit 1 -1-Test Failed this Operation cycle-fault has occurred anytime during the current operation cycle.

bit 2 -0-Pending DTC-the no. of re-occurrences and number of drive cycles

bit 3 -0-Confirmed DTC -it has been continuously active for some behavior(routine)

bit 4 -0-Test Not Completed Since last clear-if behavior(routine) is not completed.

bit 5 -1 -Test Failed Since Last Clear - After clear the DTC, again it will reappear in any operation cycle.

bit 6 -0-Test Not Completed This Operation Cycle -if monitoring routine has not run.

bit 7 -0-Warning Indicator Request -if MIL light is turn on.