My brake lights & signal lights quit working recently. have had it at 3 mechanics including the local Dodge dealer. The indicators on the dash work ok. I have replaced the BCM with a new one. The Dodge mechanic programmed it & I still had no lights. Next I replaced the IPM and FCM with a used one. We have tried a new signal switch (MFS) and brake light switch. Still ni lights. The rear upper brake light works fine.Anyone have a fix for this?

 

You've changed all the logical parts. Front turn sigs and hazards dead too? Parking lights work? Have you disconnected a tow lights harness if equipped?

Based on a wire diagram the BCM controls the turn sigs and the IPM/FCM controls the lower brake lights. The upper light circuit bypasses the BCM and FCM and is a straight power feed off the bus via the IPM (fuse box) switched by the brake light switch. This all points to processesing in the BCM and FCM and hence your brick wall. What's left? Connections and wiring. I would grab a multimeter and check all the involved wiring. Need diagrams? Send me a private message and include an email address to send them to. How? Click Cougar41 at left.

 

Hi Cougar41: Front signals and hazards are also dead.Could this be a common ground problem? Thanks in advance.

 

Boy that would be nice but I don't see it (yes I wear glasses). FCM is grounded at G300 and G101. BCM 3 wires at G301. Both tail lamp assemblies at G302 and front lights at G102. No grounds at MFS.

Have you checked for codes, specifically communication or body codes? You'll need a capable scanner. In the mean time try a cluster self test. Hold the trip button in then turn the ignition to on/run. Cluster should cycle within seconds. Codes will display in the odometer. This will indicate a limited number of communication faults in the data bus.

 

I took the GC to an independent garage & after 3 tries his part time mechanic found the problem. There was a broken wire going from the BCM to the IPM. The wire was broken inside the insulation & not visible. Saved me trading it for a vehicle that works!!!

 

Great news. Ya those are the worst. Think of how many wind up in a junkyard all for a dollars worth of 20 gauge wire. Did he happen to give specifics beyond what you stated such as a wire color ID or which contacts it went to?