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Old 06-02-2019, 09:17 PM   #2
fdryer
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Join Date: Jan 2006
Location: NYC
Posts: 43,885
 

2003 L-Series 3.0L Sedan
Default Re: Occasional Security light, ODOM deduct, P1629 code while runs

Search threads about bcm connections and rain water getting into connections and causing corrosion. The bcm has Passlock and other functions like lighting, odometer storage, door locks, ect. At best, this may be connection corrosion on terminals related to the bcm. At worst, the bcm is failing. Electric power steering isn't bcm controlled as it has its own power steering control module.

A partial reprint for DTC 1629;

Circuit Description

The powertrain control module (PCM) controls the fuel injector operation based on a vehicle theft deterrent (VTD) password from the vehicle body control module (BCM). When the ignition is first turned ON, the BCM sends a programmed theft deterrent password to the PCM. The PCM acknowledges the password and responds to the BCM that normal fuel injector operation will continue. When starting the engine, the PCM looks for a password from the BCM through the Class 2 serial data circuit. If the password is not recognized or not present, the PCM will disable the engine. If an incorrect or no password is received, fuel enable will not occur and the engine will not start. The Security indicator will flash on the instrument panel cluster (IPC) for approximately 4 seconds. If an incorrect or no password is received more than three times, this indicates that the engine is disabled for at least 10 minutes and that the Security indicator will illuminate solid on the IPC for approximately 3 seconds then flash on the IPC for 10 minutes. If the PCM loses communication with the BCM within the same ignition cycle, the vehicle will be enter fail-enable mode and continue to run on the following ignition cycles.


BCMs and ECMs are reset when battery power is removed and usually of no concern since batteries discharge from winter starting, power disconnects needed when working on electrical problems or replaced when battery life deems it necessary. Below is a copy of the electric power steering system description.

What's interesting is losing power steering, separate from bcm related issues. My initial guess is main power; battery, both battery cables and their connections (positive to fuse box and starter, two grounds - chassis and engine block). Electric power steering has its own main power connections to battery; 10 amp and 80 amp EPS fuses, wiring to battery, power steering control module, electric motor and PSCM ground.
Attached Files
File Type: pdf Service Information.pdf (98.4 KB, 2 views)
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