Cab controller module

[Rawze]

(04-16-2017 )jesseisx15 Wrote:  THANKS FOR REPLIES EVERYONE ... it wasn't doing it before but Last Year shop did ecm update so here is story
I took My 2013 Kenworth with isx 15 to shop but it was giving code for D.E.F freeze . ecm was thinking heater in not working for def tank so first he replaced valve for heater . still same problem then he saw there is an update for my DPF /SCR so he calibrated my ECM with new update ( thats when it start doing it the brake lights thing ) . but same prob again then he checked all the wiring he found there was ground wire coming from ECM about after 20 inch's after ecm . it was stretched it was hidden in wires and wrapped with heat protection . he said there were some other wire were stretched too but when the put these wires on truck they left very small slag ...

Personally, I think it is a good thing for the brake lights to be on during engine braking. you ARE slowing down after-all (or at least attempting to) and the motoring public should be aware of this fact. - just my own personal view of it no one has to agree.

I can tell you that option is NOT in the ECM of the engine. It is in the cab controller and was likely on since the truck was new, and may have even once worked properly. If it in fact it was not working and only the engine ECM update made it start working again (I say again, because it may have once worked when the truck was brand new) then the ECM update itself is not actually responsible. Someone can disagree with this all they want but there it is NOT a setting in the ECM for the brake lights. it is simply a J1939 broadcast message that is supposed to be broadcast whenever the engine brake is active. What the rest of the truck chooses to do with this message is a different issue.

I also do not agree with disabling this message in the ECM. Just not good practice to disable something that can have alternate consequences on the rest of the truck or the engine itself.

The option is in the cab controller module. It is simply reading the J1939 message for the engine brake being active. The engine ECM should normally broadcast this message on all trucks, and it is possible that for some reason unknown it was not on the old calibration (corruption, missing J1939 setting etc.). What the cab controller and other systems chooses to do with those messages is where you should look at getting changed if you want the feature off. Otherwise you will be fighting it all over again any time you need an engine ECM update.

That is all I know about it myself.