7A1±20
TRANSMISSION CONTROL SYSTEM (4L30±E)
821RW263
810RT022
PIN 1 ± (Not used)
PIN 2 ± J1850 Bus + L line on 2±wire systems, or
single wire (Class 2)
PIN 3 ± (Not used)
PIN 4 ± Chassis ground pin
PIN 5 ± Signal ground pin
PIN 6 ± PCM diagnostic enable
PIN 7 ± (Not used)
PIN 8 ± (Not used)
PIN 9 ± Primary UART
PIN 10 ± (Not used)
PIN 11 ± (Not used)
PIN 12 ± ABS diagnostic or CCM diagnostic enable
PIN 13 ± SIR diagnostic enable
PIN 14 ± (Not used)
PIN 15 ± (Not used)
PIN 16 ± Battery power from vehicle unswitched (4
AMP MAX.)
Malfunction Indicator Lamp (MIL)
The Malfunction Indicator Lamp (MIL) looks the same as
the MIL you are already familiar with (ªCHECK ENGINEº
lamp). However, OBD II requires that it illuminate under a
strict set of guidelines. Basically, the MIL is turned on
when the PCM detects a DTC that will impact the vehicle's
emissions.
The MIL is under the control of the Diagnostic Executive.
The MIL will be turned on if a component or system which
has an impact on vehicle emissions indicates a
malfunction or fails to pass an emissions±related
diagnostic test. It will stay on until the system or
component passes the same test, for three consecutive
trips, with no emissions±related faults.
Types Of Diagnostic Trouble Codes (DTCs)
The Diagnostic Executive classifies Diagnostic Trouble
Codes (DTCs) into certain categories. Each type has
different requirements to set the code, and the Diagnostic
Executive will only illuminate the Malfunction Indicator
Lamp (MIL) for emissions±related DTCs. DTCs fall into
four categories: A, B, C, and D; only types A and B are
emission±related The following descriptions define these
categories:
TYPE A
Will store the DTC and turn on the MIL (ªCheck Engineº
lamp) on the first trip in which an emission±related
diagnostic test has run and reported a ªtest failedº to the
Diagnostic Executive.
TYPE B
Will store the DTC and turn on the MIL on the second
consecutive trip in which an emission±related diagnostic
test has run and reported a ªtest failedº to the Diagnostic
Executive. After one failure, the type B DTC is ªarmed,º
or prepared to store a history code and turn on the MIL if
a second failure occurs. One passed test will disarm a
type B DTC. Some special conditions apply to misfire and
fuel trim DTCs. For a type B DTC to store and turn on the
MIL, two ignition cycles are required.
TYPE C
Will store the DTC and turn on a ªSERVICEº lamp
(ªCheck Transº lamp) on the first trip that a
non±emission±related diagnostic test has run and
reported a ªtest failedº to the Diagnostic Executive. This
type of DTC will be used in future applications.
TYPE D
Will store a DTC but will not turn on the MIL on the first
trip that a non±emission±related diagnostic test has run
and reported a ªtest failedº to the Diagnostic Executive.
These codes can be very helpful for vehicle service when
the driver may comment about a condition, but the MIL did
not turn on.
Clear DTC
NOTE: If you clear the DTC (Diagnostic Trouble Codes)
you will not be able to read any codes recorded during the
last occurrence.
