A small application of EGR could cause that drop. Brake application could cause an electrical anomaly I suppose in the PCM and make it call for EGR.
Friend had a Dodge diesel with a trans issue of TC clutch locking and unlocking just driving down the road...long, long story short..it turned out to be a transmission wire that ran close to the alternator was picking up interference from the alternator and sending errant signals. Rerouted wire, problem solved. Only took 1.5 years to find it.
Friend had a Dodge diesel with a trans issue of TC clutch locking and unlocking just driving down the road...long, long story short..it turned out to be a transmission wire that ran close to the alternator was picking up interference from the alternator and sending errant signals. Rerouted wire, problem solved. Only took 1.5 years to find it.