can i check power to the fins by putting a multimeter to the fin and then the black wire that goes to the PC?
Highly UNlikey... the quick test would be to look up one of the 14-pin or 16-pin black chips to find out which pins were +5v and ground. Then test across that chip.
Frequently the fins of a heat sink are *not* connected to any of the voltage pins.
added: you would NOT use the black lead (in my photo)... it's the WHITE lead (that connects to PC pin 5) that's the ground on that socket. (but since it's a female plug, pin (hole) 5 is a good place to just park a probe tip)
Does the OBD connector need to be plugged in? This is so Frustrating!
Yes, because it's the Sprinter that provides power to the DAD ... the PC is only a signal connection.
(so you don't have to connect the PC end of the cable for voltage testing)
The DAD's covers are just "snap-locked" on... careful probing with a thin screwdriver blade can assist in releasing the snaps. The tips of the latches are visible thru (and hold on to) the cooling vents.
good luck
--dick
p.s. if you're not used to chips (integrated circuits, or ICs), "pin 1" for all of them is to the upper right in the photo.
p.p.s. to avoid doing
more damage, you might want to seek out an electronics hobbyist (robots, arduino tiny computers, radio controlled boats or aircraft) or computer/car electronics repair shop (one that actually
does the repairs)
p.p.p.s. DADs are temperature-sensitive... mine refuses to connect to my Sprinter if it has "cold soaked" to below 50 F
(i'll try to spring some time free tomorrow to open my DAD and get the chip numbers (and thus which pins have power))
From the photo i can see that the chips at the upper right-most are HCF4011BP ...
which tells me that its power is ground on pin 7 and +5v power is on pin 14 (see diagrams)
The same pinout holds for the MC14066BCP located to the right of the finned heat sink (squint to verify).
But i
would follow your idea of using pin 5 on the PC socket to provide the "ground" test point... thus freeing you from having to hold two test probes at once...