Electrical problems on Chrysler Minivan
If you experience Electrical problems on Chrysler Minivan read this post.
The body control module (BCM) controls the power door locks, automatic door locks, door lock inhibit (child locks), chime driver, compass, trip computer, interior lighting, power liftgate, exterior lighting headlight time delay, automatic headlights, illuminated entry, backup lights, interior light fade to off feature, and instrument panel lighting. So when you see several electrical units inoperative, the cause may be the BCM. However, once the BCM receives a switched signal from the driver’s operations, it sends a digital signal to the front control module (FCM) to actually power up the intended electrical device.
If you run into a situation where electrical features do not work right after startup but do work after a while, you may be tempted to suspect the accessory relay. It may be, but you first must understand how this system works before you start replacing parts. The relay gets its power from the FCM, and the FCM gets current status from the ignition switch. When the key is out of the ignition switch, the switch reports 4.6 volts to the BCM. The voltage goes down to 4.04 volts when you insert the key, 3.2 when you turn the key to the ACC position, 1.12 volts when you turn to RUN, and 0.41 when you turn to START. To start your diagnosis of delayed electrical operation, always start at the ignition switch by checking for these voltage values. If the ignition switch doesn’t report these voltages to the BCM, the BCM will never issue digital commands to the FCM and the FCM will never power up the ACC relay.
© 2012 Rick Muscoplat
Posted on by Rick Muscoplat