Starting and Heads Up Display Issue

no not really a fuse issue your data link is shorting out and cutting out the info between ecm so there is nothing you could do with out taking out the data link short the only way to do this is find the short and eliminate it the main cause of data link issues is the qualcomm ususally

 

The only thing under fuse panel is vehicle ecu at this point pull out the dash panels for fuse box and the door in front so you can see under fuse box make sure you see whats making the noise take out all the extra cable you cut, go to the diagnostic link connector and measure the resistance between the green and the yellow datalink wire should have somewhere between 60 to 70 Ohms also between datalink and ground should have OL with ign off. if you have any kind of resistance then you got to start checking for short or an ecu going bad the easiest way i do this is unplug all the ecus one by one until the short goes away, you have trans, vehicle, engine, airbag, light control module, climate control, abs most of them located under fuse box in different layers climate control is actually the control switches that's a ecu in its own unplug them and turn ign see if you got gauges if no plug back in move to next one. also check between engine and cab connection the wires run to a big connector right in front of starter is plugged into the plastic box on side of engine check those wires running there sometimes they rub on the starter or they rub with each other causing shorts and open circuits. can you tell me what f15 fuse that keeps blowing is in that truck.

 

from your diagram do you maybe another ign switch to try cuz technicaly per your diagram this goes to one rlay so that being said you should have a short between that relay and ign switch.

 

Unlug Vecu or see if you can find test one

 

try a test vecu just needs to be volvo with d12 i dont know where you are if anywhere near chicago i can give you a test one.