GM Enhanced (OBD II) Diagnostics
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5
Not all GM vehicles support DTC status. Some only use the Global OBDII Read
Codes command. For a description of these screens, refer to the Global OBDII
section of the manual.
•History Codes — intermittent codes placed in the vehicle’s memory when
the trouble originally occurred, and will remain there even if the trouble has
been corrected. If no trouble after 50 engine warm-up cycles, the DTC will
be erased.
•Current Codes — codes transmitted through the PCM’s data stream when
a trouble condition is active and cannot be erased. The problem must be
repaired to remove the DTC.
•Intermittent Codes — indicates the current code has been set at least
once but possibly not enough to cause a history code to be stored.
•Pending Codes - These are codes that are developing, but are not quite a
Current Code.
In GM Enhanced OBD II, if DTCs are present, then three conditions (or
statuses) may accompany each DTC definition.
GM Code Types:
•MIL (Malfunction Indicator Lamp): REQUESTED or NOT REQUESTED
An emissions-related DTC is requesting the MIL (Check Engine/Service
Engine Soon) to be ON.
•Since IGN (ignition): PASS, FAIL, P/F, or NOT RUN
Provides the DTC status during this power-up. P/F (Pass/Fail) indicates the
PCM detected the DTC that passed and failed at least once during this
power-up cycle. NOT RUN means the PCM has not tested for the condition
that set the DTC during this power-up cycle.
•Since Clear: PASS, FAIL, P/F, or NOT RUN
Provides the DTC status since the last time the codes were erased.
P/F indicates the PCM test that detected the DTC passed and failed at least
once since the last Erase Code. NOT RUN means the PCM has not tested
for the condition that set the DTC since the last Erase Code.
Select Read Codes and press
ENTER
.
The Scan Tool displays the DTCs or a message stating SYSTEM PASS: NO
CODES FOUND. Scroll down to view the DTCs or press the
BACK
key to return
to the GM Function List.
GM Function List ?
1)I/M Readiness
`2)Read Codes [
3)Pending Codes ~
System Pass:
No Faults Detected.
~
DTCs Found: 13
Use [ To View DTCs
Write Down Codes
For Reference ~