I work with a family that has a ‘98 Grand AM SE (118,000 miles) that last October experienced a significant ‘change’ with lockup in Park and restrictions on shifting. The family has since been using the unlock lever beneath the shifter to retain use of the car. Before the ‘change’, the car had run well and shifting was normal. However, for a year or so before the ‘change’, there were a variety of DTCs that floated in and out .. inconsistency that we called ghosts because of a lack of a pattern. The ghost period began with P1870 with the longest interval of no DCT of 5 months. Then P0420/0422 started (no P01870) over a month then stopped. 3 months later P0442 started and P1870 reoccurred. 2 months later (Oct ‘11) the ‘change’ occurred. The DTCs from newest to oldest were: P0442, P0740, P0753, P0758, P01870. The ERLS 20 amp fuse was blown. Replacing the fuse and re-starting produced P0740; the fuse didn’t immediately blow but did over time. In 2005, the transmission was rebuilt. My question is .. does anyone have a thought on where to look for the short? Is this something that should go to a dealership? The family’s resources are very limited.