Isuzu 1999 RODEO Workshop Manual page 1654

Diagnostic Trouble Code (DTC) P1618 Serial Peripheral Interface (SPI)
Circuit Description
The serial peripheral interface (SPI) communication is
used internally by the PCM to send messages between
the engine processor and the automatic transmission
processor. Included in each message sent between the
two-processors is a checksum of the message. Both the
engine processor and automatic transmission processor
will compare this check sum value with the calculated
value. If the checksums don't match, the processor will
view the new data as being corrupted and ignore the
values. The processor will then use the previous
message. The receiving processor will then send a
message to the sending processor informing it that it's
last message was corrupted.
Conditions for Setting the DTC
f Battery voltage is above 9.0 V for 2 seconds.
f The PCM detects an internal program fault (check sum
of data communications error).
f Check sum fault present for 3 out 6 seconds.
f No TCM resets for 2 seconds.
DTC P1618 – Serial Peripheral Interface (SPI) PCM Interprocessor
Step
1 Was the "On-Board Diagnostic (OBD) System Check"
performed?
2 Is the EEPROM calibration the latest version
available?
3 Reprogram the PCM with the latest available
calibrations.
Does DTC 1618 re-appear when the OBD System
Check is repeated?
4 Replace the PCM.
IMPORTANT: The
programmed.
Powertrain Control
procedures.
And also refer to latest service bulletin
Check to see if the Latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.
Is the action complete?
RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS
Interprocessor Communication Error
Communication Error
Action
replacement PCM
Refer to On-Vehicle Service in
Module and Sensors
Action Taken When the DTC Sets
f The PCM will flash the "Check Trans" lamp the first
time the fault is detected.
f The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
f The automatic transmission will operate in the "safety
mode" to protect the mechanical parts of the
transmission. Shift quality and/or gear changes may
not be normal.
Conditions for Clearing the MIL/DTC
f The PCM will turn the "Check Trans" lamp "OFF" on
the third consecutive trip cycle during which the
diagnostic has been run and the fault is no longer
present.
f A history DTC P1618 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
f DTC P1618 can be cleared by using the Tech 2 "Clear
Info" function or by disconnecting the PCM battery
feed.
Value(s)
—
—
—
must be
for
—
6E2–411
PCM
Yes No
Go to OBD
System
Check
Go to Step 2
Go to Step 4 Go to Step 3
Repair
Go to Step 4
completed
Verify repair —