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10-09-2010 04:00 PM |
I determined that the module was faulty through a series of steps. When I start the vehicle and drive it for about 10 mins, the yellow lights appear. This is the indication of a possible thermal issue. The next morning when the X5 was cold, I removed the drivers side head light which allows clear access to the module. I Got out the hair dryer and heated the module slightly (truck not started but key one position before spring loaded starter position) and sure enough the lights came on. Turning the ignition switch off and removing the key now, back to the front of the X5. Now with a can of Super Cold Spray, I cooled the module and re insert the key into the ignition, turn it one step before the starter position again, and now no yellow lights. This has now determined that the problem is the module and it is a thermal issue. So out came the module and on my test bench it went. There were quite a few problems in my module. Failing surface mount capacitors and intermittant connections. I imagine this is due to thermal cycling. This is not a job for anyone without surface mount re-work equipment and very steady hands. There is gold bonding wires in this box finer than a hair, under a silicone flexible jelly. If this jelly is disturbed in the wrong area just once, the whole unit is not repairable, as these bonding wires attach directly to the semiconductor and processor dyes. The whole internal circuit is on a porcelain substrate which makes soldering difficult because the substrate sinks the heat away from the equipment. There are also 2 diodes and an electrolytic capacitor behind the 2 heat sinks on the solenoid side (Bottom of the unit) There is no access to these parts unless the spot welded tabs are removed. There are 2 semiconductors attached to each heatsink. These semiconductors are also welded to internal tabs (No soldering in this part)
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