DESCRIPTION & OPERATION
| WARNING | Deactivate air bag system before performing any service operation. See appropriate AIR BAG RESTRAINT SYSTEMS article. Do not apply electrical power to any component on steering column without first deactivating air bag system. Air bag may deploy. |
The Body Control Module (BCM) controls the following functions: Remote Keyless Entry (RKE) system, Content Theft Deterrent (CTD) system, chimes, fasten seat belt indicator, Retained Accessory Power (RAP), power door locks, rear compartment lid release and interior lights.
Signals that activate BCM are known as "wake-up" signals. BCM is asleep when it is not controlling or monitoring the following wake-up functions: courtesy light system, remote keyless entry system, ignition switch, parking lights, headlights, door jamb switches, rear compartment lid ajar indicator switch, key-in-ignition switch and shock sensor inputs. When BCM is awake and wake-up signal is removed for 10 minutes, BCM will return to sleep. If BCM receives a door ajar wake-up signal and wake-up remains active after 10 minutes, BCM will turn off courtesy light (if illuminated) to prevent battery drain.
BCM battery terminals operating current should not exceed 75 milliamps while BCM is awake with ignition switch in OFF position. An approximate normal value with ignition switch in RUN position is 250 milliamps. If RAP is active, amperage may be higher. RAP allows operation of power door locks, convertible top and radio until 10 minutes have elapsed or a door is opened. When BCM is asleep, current should not exceed 2 milliamps (3 milliamps with theft deterrent system). BCM will go to sleep after ignition is turned off and 10 minutes has elapsed. BCM IGN 1 and IGN 3 terminals operating current should not exceed 15 milliamps. Most BCM functions will properly operate with a system voltage of 9-16 volts.
Description
DTC 12 is always displayed as the first DTC, indicating Body Control Module (BCM) is in diagnostic mode and DTC display is in progress. If DTCs do not display, go to TESTING . If DTCs display, go to appropriate diagnostic procedure. See BCM DTC DEFINITIONS table under SELF-DIAGNOSTIC SYSTEM.
Body Control Module (BCM) provides a 12-volt input to courtesy lights on courtesy lights feed circuit when commanded by instrument panel dimmer switch, door jamb switch or rear compartment lid ajar indicator switch inputs.
DTC 21 will set when battery circuit is open due to a problem with COURTESY fuse No. 8, faulty harness or connector, courtesy lights feed circuit is shorted to ground for more than 50 milliseconds while BCM is providing input on circuit, or BCM is defective.
When DTC 21 is set, courtesy lights will not come on and instrument panel dimmer switch will not operate. Glove box and center console lights will also be inoperative. DTC 21 will clear when fault is corrected and memory is cleared.
Body Control Module (BCM) provides a ground path to courtesy lights on courtesy lights return circuit when commanded by instrument panel dimmer switch, door jamb switch or rear compartment lid ajar indicator switch inputs.
DTC 22 will set when courtesy lights return circuit is shorted to battery for more than 50 milliseconds while BCM is providing ground for circuit.
When DTC 22 is set, courtesy lights will not come on and instrument panel dimmer switch will not operate. Glove box and center console lights will operate normally. DTC 22 will clear when fault is corrected and memory is cleared.
Retained Accessory Power (RAP) is enabled when ignition switch is turned to RUN position. RAP will continue to supply power to power windows, radio and convertible top for up to 10 minutes after ignition switch is turned to OFF position. RAP will shut off if any door is opened during this 10 minute period. Body Control Module (BCM) provides RAP function through RAP feed circuit to WINDOWS circuit breaker No. 15 (30-amp) and RADIO fuse No. 17 (15-amp) located in instrument panel fuse block.
DTC 23 will set when BCM detects RAP output on RAP feed circuit is either shorted to ground with RAP enabled or shorted to battery with RAP disabled for more than 50 milliseconds. DTC will also set if there is an open in Red wire between BCM and fusible link "E".
When DTC 23 is set, RAP will not operate (shorted to ground) or RAP will not deactivate when door is opened (shorted to battery). DTC 23 will clear when fault is corrected and memory is cleared.
Body Control Module (BCM) provides a 12-volt output to fasten seat belt indicator, located on instrument cluster, while driver's seat belt is unfastened.
DTC 24 will set when BCM detects fasten seat belt output is either shorted to ground or shorted to battery for more than 50 milliseconds.
When DTC 24 is set, fasten seat belt indicator will not come on when ignition is on and driver's seat belt is not fastened, or fasten seat belt indicator is always illuminated. DTC 24 will clear when fault is corrected and memory is cleared.
Note. DTC 35 is required for Content Theft Deterrent (CTD) operation. SECURITY indicator must be detected for alarm to function.
Body Control Module (BCM) provides an output on security indicator Light Emitting Diode (LED) control circuit to SECURITY indicator LED.
DTC 25/35 will set when ignition is turned on and BCM does not detect a security LED control circuit through BCM connector C3 terminal C16. Presence of security LED control circuit connected through connector C3 at time of battery connection is required for proper CTD operation.
Digital Radio Frequency (RF) message received from Remote Keyless Entry (RKE) transmitter was valid, and all security checks passed. No malfunction is present. RKE transmitter should operate all functions properly (i.e., lock, unlock, etc.).
If RKE transmitter digital RF message is sent, but Diagnostic Trouble Codes (DTC) 41-45 are not set as well, RKE transmitter may be defective. If RKE transmitter digital RF message is sent and DTCs 41-45 are set, but corresponding RKE transmitter function does not operate, Body Control Module (BCM) or harness may be defective.
Digital Radio Frequency (RF) message received was from a Remote Keyless Entry (RKE) transmitter not programmed to Body Control Module (BCM). RKE transmitter function capabilities will not exist.
DTC 42 will set when RKE transmitter was used without programming it to BCM. If RKE transmitter was already programmed, RKE transmitter may be defective. DTC 42 will also set if another RKE transmitter was operated in the same area.
BCM should be placed in RKE system programming mode. All RKE transmitters must be programmed to BCM during same programming mode cycle. See REMOTE KEYLESS ENTRY (RKE) TRANSMITTER PROGRAMMING under PROGRAMMING.
The digital RF message received was from a Remote Keyless Entry (RKE) transmitter that is programmed to Body Control Module (BCM), but message did not pass sumcheck security test. No remote function capabilities will exist.
DTC 43 will set when BCM is in diagnostic mode, any RKE transmitter button is pressed and RKE transmitter signal does not pass sumcheck security test. Most likely cause is that RKE transmitter is out of synchronization.
The digital RF message received was from a Remote Keyless Entry (RKE) transmitter that is programmed to Body Control Module (BCM), but message did not pass encryption security test. No remote function capabilities will exist.
DTC 44 will set when RKE transmitter has been in program or synchronize mode while out of range of BCM. Fault may also be present if digital RF message has an error. Most likely cause is that RKE transmitter is out of synchronization.
At least 50 consecutive digital RF messages were received from a Remote Keyless Entry (RKE) transmitter that is programmed to Body Control Module (BCM), but message did not pass encryption security test. BCM will cease processing any RKE transmitter digital RF messages (good or bad) for 20 seconds. No remote function capabilities will exist.
DTC 45 will set when RKE transmitter has been in program or synchronize mode while out of range of BCM. Fault may also be present if RKE transmitter is defective. Fault could be induced prior to BCM entering diagnostic mode. Most likely cause is that RKE transmitter is out of synchronization with BCM.
DTC 55 is always displayed when Body Control Module (BCM) is in diagnostic mode. DTC 55 indicates that the next 2 numbers displayed are BCM hardware and software configurations. First number following DTC 55 is the hardware configuration. The second number is the software configuration. After configuration numbers are displayed, entire DTC list will repeat beginning with DTC 12.