Code P0477 Exhaust Pressure Control Relay Low

[WStrmiska]

Hi everyone,I just installed a PacBreak and I got a code P0477. The pack brake didn't work because of a faulty pressure switch which I had to order. I started and stopped the engine 3 or 4 times after I installed the PacBreak to see if I got any codes and none came up until today. I'm thinking it might be the exhaust elbow, might not be tight enought but I'm not sure. Can someone explain to me what this code actually means and if I can fix the problem my self and clear the code my self. Thanks

 

[sag2]

It means the exhaust brake driver out of the ECM does not match the return circuit back to the ECM. I'm assuming you added two wires to the ECM to control the relay. The ECM is sending out either B+ or a ground, but on the return wire the controller is seeing something different. So if the ECM is sending out B+ it is not seeing any voltage returning. So it could be one of the wires is shorted to B+, ground, in the wrong position in the connector, not seated in the connector etc. To properly test it you need a scan tool to actuate the brake driver in the ECM.

But first verify you installed the wires in the ECM in the correct position and they are properly seated.