L9930 Dual Full Bridge Question

Thread Starter

bwilliams60

Joined Nov 18, 2012
1,317
Working on an automotive ECM and seeing odd voltages on this board. I am comparing to a known good board but I think I am coming to a conclusion. Here are the voltages as measured at the bad L9930 (left side) as well as the ones measured at the good L9930 (right side):

Pin 1 0.001 VDC 0.004 VDC
Pin 2 13.75 VDC 13.75 VDC VBAT
Pin 3 0.003 VDC 0.003 VDC
Pin 4 0.004 VDC 0.004 VDC
Pin 5 0.004 VDC 0.004 VDC
Pin 6 0.004 VDC 0.004 VDC Gnd
Pin 7 0.003 VDC 4.860 VDC
Pin 8 0.005 VDC 4.96 VDC
Pin 9 0.004 VDC 0.004 VDC
Pin 10 13.76 VDC 13.76 VDC VBAT
Pin 11 0.001 VDC 13.76 VDC

Is there a way to test these on or off the board? I think this is my problem but would like to be sure. Thoughts?
 

GopherT

Joined Nov 23, 2012
8,012
I would look why pins 7 and 8 (input and enable) are not getting driven high. I think your problem is upstream of the dual bridge chip.
 
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