OPERATION
The Powertrain Control Module is a pre-programmed, microprocessor-based digital computer. It regulates ignition
timing, air-fuel ratio, emission control devices, charging system, certain transmission features, speed control, air
conditioning compressor clutch engagement and idle speed. The Powertrain Control Module can adapt its programming
to meet changing operating conditions.
The Powertrain Control Module receives input signals from various switches and sensors. Based on these inputs,
the Powertrain Control Module regulates various engine and vehicle operations through different system components.
These components are referred to as Powertrain Control Module outputs. The sensors and switches that
provide inputs to the Powertrain Control Module are considered Powertrain Control Module inputs.
The Powertrain Control Module adjusts ignition timing based upon inputs it receives from sensors that react to:
engine rpm, manifold absolute pressure, engine coolant temperature, throttle position, transmission gear selection
(automatic transmission), vehicle speed and the brake switch.
The Powertrain Control Module adjusts idle speed based on inputs it receives from sensors that react to: throttle
position, vehicle speed, transmission gear selection, engine coolant temperature and from inputs it receives from the
air conditioning clutch switch and brake switch.
Based on inputs that it receives, the Powertrain Control Module adjusts ignition timing. The Powertrain Control Module
also adjusts the generator charge rate through control of the generator field and provides speed control operation.
STANDARD PROCEDURE - PCM/SKREEM PROGRAMMING
Note: Before replacing the PCM, be sure to check the related component/circuit integrity for failures not
detected due to a double fault in the circuit. Most PCM failures are caused by internal component failures
(i.e. relays and solenoids) and shorted circuits (i.e. pull-ups, drivers, and switched circuits). These failures
are difficult to detect when a double fault has occurred and only one DTC has been set.
When a Powertrain Control Module (PCM) and the Sentry Key Remote Entry Module (SKREEM) are replaced at the
same time, perform the following steps:
1. Program the new PCM.
2. Program the new Sentry Key Remote Entry Module.
8E - 54 ELECTRONIC CONTROL MODULES - SERVICE INFORMATION ZH
3. Replace all ignition keys and program them to the new Sentry Key Remote Entry Module.
PROGRAMMING THE PCM
The Sentry Key Remote Entry System Secret Key is an ID code that is unique to each Sentry Key Remote Entry
Module. This code is programmed and stored in the Sentry Key Remote Entry Module, the PCM, and the ignition
key transponder chip(s). When replacing the PCM, it is necessary to program the secret key into the new PCM
using the DRBIIIT scan tool.
Note: If three attempts are made to enter secure access mode using an incorrect PIN, secured access mode
will be locked out for one hour. To exit this lockout mode, turn the ignition switch to the ON position for one
hour, then enter the correct PIN. (Ensure all accessories are turned off. Also monitor the battery state and
connect a battery charger if necessary).
PROGRAMMING THE SENTRY KEY REMOTE ENTRY MODULE
Note: Be sure to enter the correct country code. If the incorrect country code is programmed into the Sentry
Key Remote Entry Module, it cannot be changed and the Sentry Key Remote Entry Module must be
replaced.
1. Program ignition keys to the Sentry Key Remote Entry Module.
Note: If the PCM and the Sentry Key Remote Entry Module are replaced at the same time, all vehicle ignition
keys will need to be replaced and programmed to the new Sentry Key Remote Entry Module.
PROGRAMMING IGNITION KEYS TO THE SENTRY KEY REMOTE ENTRY MODULE
Note: A maximum of eight keys can be learned to each Sentry Key Remote Entry Module. Once a key is
learned to an Sentry Key Remote Entry Module it (the key) cannot be transferred to another vehicle.
1. Obtain ignition keys to be programmed from the customer (8 keys maximum).
2. Using the DRBIIIT, erase all ignition keys.
3. Program all of the ignition keys.
If ignition key programming is unsuccessful, the DRBIIIT will display a failure message.