FCM, Cluster parasitic draw, brake lights on.

[Andres]

My '03 has an electrical problem. The rear brake lights stay on even though the brake switch seems to work and is not out of adjustment.



If I pull the brake light bulbs, a parasitic draw of 1. 4 amps still exists.



If I pull the fuse for the cluster, the draw goes to 0. 0.



The brake lights seem to be back fed, perhaps thru a failing FCM or cluster.



If I pull the FCM, the draw drops from 1. 4a to 1. 0 amp.



I've pulled all the relays, and all the larger fuses and still have the draw.



The power distribution module does click about 1/2 second after the battery is connected.



Any ideas?



Thanks.

 

[TCDiesel]

The B-Switch is not serviceable, either it works or don't... My guess is the FCM. . it is also possible PDC is the problem check your trailers lights if all are working. I will see if I can post the wiring specs so you can run it down to the PDC.

 

[TCDiesel]

Is the center High mounted stop lamp also on? or just the service lamps?

 

[TCDiesel]

The B-Switch sends power to the service lights independent of the high mounted stop lamp B-switch is good, Check the LB/WT wire in the C4 connection under the IPM, if it is hot the FCM is most likely the cause.

 

[sag2]

Something is keeping the cluster awake. You need to approach it systematically. First pull the brake light switch connector. If the draw is still there pull all the fuses one at a time. If the cluster fuse is still the one that kills the draw, it does not mean anything is wrong with the cluster. The next step is to pull the cluster connectors one at a time and see which one stops the draw. Next you have to pull the terminals from the affected connector until you find the circuit that is keeping it awake. I usually pull one row at a time and use process of elimination to find it the fastest. I generally focus on lamp circuits as they are the most likely cause. Double check the wire colors against the service manual before you start as sometimes the wire colors are not as spelled out in the service manual. Keep in mind it can be a bad ground on any other circuit and that circuit is trying to ground through a cluster circuit. Draws are usually not that much fun, but if the draw is constant that is the best failure you can have to diagnose.

 

[ParsonsDRW]

I think that i may need a new front control module. Were is the best place to get one or is it dealer only.

Ben

 

[Scrappy]

do you have a trailer brake controller?

I ask because I had a similar issue with my truck. my brake lights would turn on in the middle of the night and also occasionally while driving w/o pedal input.

When I disconnected my brake controller it would not do it any more.

I don't know if that would cause the draw thru the cluster though. is the lamp out feature in the cluster? does the brake controller get power from the same circuit as the cluster?

 

[DShockey]

I have an 06, i installed one of those LED lights that goes sise to side under the tailgate and I have same issue.

 

[TCDiesel]

Andres, I can email schematics; the site does not allow the size of the four Pages...

 

[TCDiesel]

I have replace the IPM & the FCM in my 2003, the factory IPM/FCM is weak. . the new updated FCM comes with much stronger lamp out circuits and a better circuit board in the IPM unfortunately the two component's retail for over $600. 00.

 

[Bob V]

I have had good luck with parts from Mopar Parts for Dodge, Chrysler and Jeep: MoparPartsAmerica

 

[Andres]

Problem solved! After replacing the FCA, the brake lights remained on and even after pulling the bulbs the system had a parasitic draw of about an amp. The cluster wasn't going to sleep.



Replaced cluster today ($265 + $500 core), brake lights work and cluster goes to sleep after about a minute. FWIW, any activity (like hazards, tapping brakes, etc) with key off wakes up the cluster internally and then it goes back to sleep .



I installed the old FCA and it functions fine, so I'll either keep the new FCM or ebay it, after I return the old cluster for that core charge. HaHa. I don't think DC will take back an electrical part.

 

[sag2]

Sorry to see you had to waste the money on the FCM. As I posted earlier you have to approach these things logically and you can find the problem without throwing parts at them.