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Home >> Chrysler Truck >> 2002 >> PT Cruiser L4-2.4L VIN B >> Repair and Diagnosis >> Relays and Modules >> Relays and Modules - Powertrain Management >> Relays and Modules - Computers and Control Systems >> Body Control Module >> Description and Operation >> Functional Operation >> Part 2 of 4

Part 2 of 4

SPECIAL TOOLS
Some airbag diagnostic tests use special tools, 8310 and 8443 airbag load tools, for testing squib circuits. The load tools contain fixed resistive loads, jumpers and adapters. The fixed loads are connected to cables and mounted in a storage case. The cables can be directly connected to some airbag system connectors. Jumpers are used to convert the load tool cable connectors to the other airbag system connectors. The adapters are connected to the module harness connector to open shorting clips and protect the connector terminal during testing.

When using the load tool follow all of the safety procedures in the service information for disconnecting airbag system components. Inspect the wiring, connector and terminals for damage or misalignment. Substitute the airbag load tool in place of a Driver or Passenger Airbag, seat airbag, clockspring, or seat belt tensioner (use a jumper if needed). Then follow all of the safety procedures in the service information for connecting airbag system components. Read the module active DTC's. If the module reports NO ACTIVE DTC's the defective components has been removed from the system and should be replaced. If the DTC is still active, continue this process until all components in the circuit have been tested. Then disconnect the module connector and connect the matching adapter to the module connector. With all airbags disconnected and the adapter installed the squib wiring can be tested for open and shorted conditions.

DIAGNOSTIC TROUBLE CODES
Airbag diagnostic trouble codes consist of active and stored codes. If more than one code exists, diagnostic priority should be given to the active codes.

Each diagnostic trouble code is diagnosed by following a specific testing procedure. The diagnostic test procedures contain step-by-step instructions for determining the cause of the trouble codes. It is not necessary to perform all of the tests in this book to diagnose an individual code.

Active diagnostic trouble codes for the airbag system are not permanent and will change the moment the reason for the code is corrected. In certain test procedures within this manual, diagnostic trouble codes are used as a diagnostic tool.

Active Codes
The code becomes active as soon as the malfunction is detected or key-off, whichever occurs first. An active trouble code indicates an on-going malfunction. This means that the malfunction is currently there every time the control module checks that circuit/function. It is impossible to erase an active code; active codes automatically erase by themselves when the reason for the code has been corrected.

With the exception of the warning lamp trouble codes or malfunctions, when a malfunction is detected, the airbag lamp remains lit for a minimum of 12 seconds or as long as the malfunction is present.

An "Interrogate Right SIACM or Interrogate left SIACM" diagnostic trouble code indicates an active trouble code in the respective module.

Stored Codes
Airbag codes are automatically stored in the ACM's memory as soon as the malfunction is detected. A "stored" code indicates there was an active code present at some time. However, the code currently may not be present as an active code, although another active code could be.

When a trouble code occurs, the airbag warning lamp illuminates for 12 seconds minimum (even if the problem existed for less than 12 seconds). The code is stored, along with the time in minutes it was active, and the number of times the ignition has been cycled since the problem was last detected. The minimum time shown for any code will be one minute, even if the code was actually present for less than one minute. Thus, the time shown for a code that was present for two minutes 13 seconds, for example, would be three minutes.

If a malfunction is detected a diagnostic trouble code is stored and will remain stored as long as the malfunction exists. When and if the malfunction ceases to exist, an ignition cycle count will be initiated for that code. If the ignition cycle count reaches 100 without a reoccurrence of the same malfunction, the diagnostic trouble code is erased and that ignition cycle counter is reset to zero. If the malfunction reoccurs before the count reaches 100, then the ignition cycle counter will be reset and the diagnostic trouble code will continue to be a stored code.

If a malfunction is not active while performing a diagnostic test procedure, the active code diagnostic test will not locate the source of the problem. In this case, the stored code can indicate an area to inspect.

If no obvious problems are found, erase stored codes, and with the ignition "ON" wiggle the wire harness and connectors, rotate the steering wheel from stop to stop. Recheck for codes periodically as you work through the system. This procedure may uncover a malfunction that is difficult to locate.

Occupant Restraint System Trouble Codes
The Occupant Restraint System contains three modules ACM, Left SIACM and Right SIACM (If equipped with SIACM) that store active and stored DTC's. Some DTC's will require replacing the implicated module. Other DTC's will require some Diagnostic procedures to determine defective components.

AUDIO SYSTEM
The audio system on the 2002 PT/PG consists of a radio that communicates over the PCI Bus. Each radio system comes equipped with a standard premium 6 speaker system. The speakers are located in the instrument panel, the front doors and the rear "D" pillars. The instrument panel speakers are a tweeter type speaker for high frequency. The front door speakers are a woofer/midrange type speaker. The rear "D" pillar speakers are a full range type speaker. If one of the speaker circuits experiences a short, the other speakers on that channel will also shut down until the circuit is repaired. The radio will also set a trouble code, which the DRB III can display.

COMPASS/TEMPERATURE MODULE (CTM)
The overhead console houses the Compass/Temperature Module display and two reading and courtesy lamps. This display provides the outside temperature and one of eight compass readings to indicate the direction the vehicle is facing. The Ambient Temperature Sensor (ATS) monitors outside temperature and is hardwired to the Compass/Temperature Module.

There is a STEP button for the compass/temperature display located forward of the power sunroof switch (if equipped), between the lamps.

The STEP button is used to toggle the compass/temperature display to select either F°, C°, or OFF. When the vehicle is first turned ON, you may select:
- Blank display
- Compass/Temperature displayed in Fahrenheit (F°)
- Compass/Temperature displayed in Celsius (C°)

Depress and release the STEP button to cycle through the above display modes.

Setting Magnetic Zone Variance
Variance is the difference between magnetic North and geographic North. For proper compass function, the correct variance zone must be set. Refer to the Zone Variance map for the correct zone.

Follow these steps to check or change the variance zone:
- The ignition switch must be in the ON position and the Compass/Temperature Module display must not be blank.
- Depress and hold the STEP button for 5 - 10 seconds until ZONE appears in the display, then release the STEP button. The number displayed is the variance zone currently stored in the compass memory.
- To change the zone, depress the STEP button to scroll through the zone numbers 1 through 15, until the desired zone is displayed.
- After selecting the zone, wait approximately 15 seconds until the display returns to normal.




Compass Calibration
NOTE: Upon installation of a new overhead console, with the ignition ON, "CAL" will be illuminated in the display but the compass will not calibrate for 30 ignition cycles or 15 starts, OR until manually calibrated. For this reason, manual calibration of the compass is recommended after any replacement or appearance of the compass/temp display being "locked-up."

Manual calibration
After any replacement or the appearance of a locked-up condition, you must calibrate the compass. Follow these instructions in order to ensure correct compass calibration:
- Drive the vehicle to an area away from any large metal objects or overhead power lines.
- Ensure that the proper variance zone is selected. See "Setting Magnetic Zone Variance."
- With the engine running, depress and hold the STEP button for 10 - 15 seconds.
- ZONE will appear in display, then CAL.
- Release the STEP button within 2 seconds of CAL illuminating.
- CAL is displayed.
- Drive slowly, less than 5 MPH (8 KPH) in 3 complete 360 degree circles.
- CAL will stay illuminated to alert the driver that the Compass/Temperature Module is in the calibration mode.
- After calibration, the CAL will turn OFF.

Auto calibration mode
During normal vehicle operation, the Compass/Temperature Module will continuously update the compass calibration to compensate for changes in the vehicle's magnetic field. If the Compass/Temperature Module appears to be "locked-up" or the compass displays false indications, the vehicle may need to be demagnetized. Refer to Demagnetizing Procedure.

Outside Temperature
NOTE: Engine temperature or the vehicle experiencing a "hot soak" condition can increase the temperature near the ambient temperature sensor. The displayed temperature may appear to update slowly until the vehicle is driven and the compass performs directional updates.

The displayed outside temperature information is stored within the compass/temp module. When the Compass/Temperature Module is first powered up, it retrieves the temperature data from the module memory. The memory temperature is compared with the temperature received from the ambient temperature sensor (ATS). The colder of the two temperatures is displayed.

Temperature update - warm
On power up, when the outside temperature sensed by the ATS is warmer than the temperature stored in the module memory, the Compass/Temperature Module will update the displayed temperature to the outside air temperature within 30 seconds after it has detected that the vehicle has been moving for 2 minutes.

Temperature update - cold
On power up, when the outside air temperature sensed by the ATS is colder than the stored memory temperature, the Compass/Temperature Module will update the displayed temperature to the outside temperature at a rate of -1 °F every 2 seconds, regardless if the vehicle is moving or not.

Extreme temperature / open or short circuit condition
If the measured outside temperature is more than 60 °C (140 °F) or the ATS sense circuit is shorted to ground, the temp display will be 60 °C (140 °F) to indicate a short circuit condition.

If the measured outside temperature is less than -45 °C (-49 °F) or the ATS sense circuit is open, the temp display will be -45 °C (-49 °F) to indicate an open circuit condition.

Ambient Temperature Sensor
The ambient air temperature is monitored and displayed by the compass/temp module. The Compass/Temperature Module receives a hardwire input from the ambient temperature sensor (ATS). The ATS is mounted on the center support brace in front of the A/C condenser, behind the front grille.

The ATS cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.

The ATS is a variable resistor that operates on a 5-volt reference signal circuit hardwired from the Compass/Temperature Module. The resistance in the ATS changes as the outside temperature rises or falls. The Compass/Temperature Module senses the change in reference voltage through the ATS resistor. Based on the resistance of the ATS, the Compass/Temperature Module is programmed to correspond to a specific temperature. The Compass/Temperature Module then displays the proper ambient temperature.
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