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LOGAN541 is back, BCM question

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Logan541

New member
I have been having an issue with my car on and off for years now since the last time in april 2014 I parked it and bought a new car but I really want to get the Prix back on the road. Rather than go through all the symptoms again, I have an idea, can you guys tell me what the symptoms of a bad BCM would be? I am told they never go bad but have a hunch before I change it I want to see if this is it.

Thanks all

Logan
 


I think I just caught something, so are you saying that changing the BCM may not fix the issue because it may have permanently damaged something that it controls, and we really can't narrow down which part?
 
Without knowing your year or the symptoms you were experiencing, I will ask....

Have you checked the BCM for trouble codes?
 


Diagnostic System Check - Body Control System
System Description
The body control module (BCM) diagnostic system check identifies
conditions that are associated with the BCM. The following test is the
starting point for any BCM concern or complaint. The test directs you
to the next logical step in diagnosing the complaint.

The BCM is a reliable component and is not likely to cause the malfunction.

The following items cause most system complaints:

•Faulty wiring
•Faulty connectors
•Faulty components
Understand the computer system and use the tables correctly in order
to achieve the following results:

•Reduce diagnostic time
•Prevent unnecessary parts replacement
Diagnostic Aids
The following conditions may result in an intermittent operation of
the BCM with no DTC stored:

•Any condition which results in the interruption of power to the BCM
•Out of range battery voltage specification. Normal battery voltage is
9–16 volts.
•A loose or damaged ground(s)
An intermittent failure in the electronic system may be difficult to
detect and accurately diagnose. The BCM tests for the different
malfunctions under different vehicle conditions. A test drive may
cause a malfunction to repeat. If the system malfunction is not
repeated during the test drive, a good description of the complaint
may be useful in locating an intermittent fault condition.

Faulty electrical connections or wiring cause most intermittent
problems. If you suspect an intermittent condition, inspect the
suspected circuits for the following conditions:

•Poor mating of the connector halves or backed out terminals
•Improperly formed or damaged terminals
•Wire chafing
•Poor wire to terminal connections
•Dirty or corroded terminals
•Damage to the connector bodies
Use a J 35616-A for diagnostic procedures that require probing or
testing a terminal. Use of the J 35616-A ensures the following
results:

•No damage occurs to the terminal.
•The tool determines if contact tension is sufficient.
DTC P1626 will set in the powertrain control module (PCM) if the
following conditions exist:

•The ignition is in the RUN position.
•The BCM is disconnected.
When the BCM diagnostics and repairs are completed, refer to Engine
Controls - 3.1L (LG8) or Engine Controls - 3.8L for additional
information on the PCM related DTCs.

Test Description
The number(s) below refer to the step number(s) on the diagnostic table.

1.This step checks if the BCM identifies the BCM type.
2.This step checks if vehicle has the correct BCM type installed.
3.This step checks for DTCs stored in BCM memory. ←Your concern
4.This step checks for an open in CKT 1550.
5.This step checks for an open in CKT 443.
6.This step checks for a short to B+ in CKT 443.
Diagnostic System Check - Body Control System Step
Action
Value(s)
Yes
No

1
1. Close all of the doors.
2. Turn the ignition switch to the OFF position.
3. Remove the MALL PGM fuse located in the fuse block.
4. Turn the ignition switch to the ACC position.
When the BCM enters the feature customization mode, the BCM identifies
the type by flashing the fasten belts indicator lamp (and sounding the
chime) a number of times equal to the BCM type number.

Does the BCM identify its type number?
—
Go to Step 2
Go to Step 4

2
Refer to Body Control System Circuit Description for details on BCM types.

Does the BCM type match vehicle equipment/option content?
—
Go to Step 3
Go to Step 7

3
Within one second, turn the ignition switch from the ACC position to
the OFF position, then back to the ACC position.

Upon cycling the ignition switch as described above, the BCM enters
the diagnostic/programming mode. At this point, the BCM may flash (and
chime) any diagnostic trouble codes (DTCs) stored in memory (if any).
DTC numbers range between 1–8. Refer to Body Control System Circuit
Description for more information regarding DTCs.

Is the BCM displaying any DTCs?
—
Go to the appropriate DTC
System OK

4
1. Turn the ignition switch to the OFF position.
2. Disconnect the BCM connector C1.
3. Use a test light in order to connect between B+ and the BCM
harness connector C1 terminal D.
Is the test light on?
—
Go to Step 5
Go to Step 8

5
1. Turn the ignition switch to the RUN position.
2. Use a test light in order to connect between the BCM harness
connector C2 terminal D4 and ground.
Is the test light on?
—
Go to Step 6
Go to Step 9

6
1. Leave test light connected (from step 17).
2. Turn the ignition switch to the OFF position.
Is the test light off?
—
Go to Step 11
Go to Step 10

7
Replace the BCM with the correct BCM type, according to the vehicle
equipment content/options. Refer to Body Control Module Replacement.

Is the repair complete?
—
System OK
—

8
Repair a poor connection or an open in CKT 1550.

Is the repair complete?
—
System OK
—

9
Repair a poor connection or an open in CKT 443.

Is the repair complete?
—
System OK
—

10
Repair a short to voltage in CKT 443.

Is the repair complete?
—
System OK
—

11
1. Inspect the BCM connectors for poor terminal contact. Repair as needed.
2. If the BCM connector terminal contact is OK, replace the BCM.
Refer to Body Control Module Replacement.
Is the repair complete?
—
System OK
 
Some real useful information Brandon, I am going to check on this soon as I get the timer in about two weeks, thanks
 
No problem! I had an issue where my interior lights wouldn't shut off. I know how frustrating interior electrical diagnosis is. The fault code given by the BCM was the only way I could have found it.
 


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