Solved in the Details....(aka I'm a dummy)
Ok I've found and fixed the problem. First of all let me say, I'm a dummy. And I have to pay attention to the details. Also, thanks for the tip about the wiring under the battery. It was very dirty there and needed a cleaning. I got the grounds nice and clean.
Last week I thought I should try and get the correct bulbs for a VW, thinking I had the wrong ones. The "auto stores" never listed a bulb number for a '98 jetta, but there was a listing for golfs, so I figured it was close enough. So last weekend I searched for VW bulbs and found the following...
From
Autohause Arizona
<snip>
not recommended to mix nickel base with brass base due to higher efficiency (lower wattage) of nickel base bulbs.
</snip>
What I didn't do is carefully check the rear bulb. In Nov. of last year I replaced the left turn single bulb with an nickel based bulb. Last week I checked for the brass bulb, but didn't find a brass bulb.
Yesterday I had made up my mind that the problem was with a ground. I found in the trunk that the CD changer and tail light module was grounded in the trunk. I removed the changer, then I removed the ground from the tail light module. The marker lights ( side and front ) worked! So now I figure the problem is in the tail light module. Inspecting the module, I couldn't find a break or damage that would cause a short.
Then I noticed the markings on the bulb in the tail light module, the bulb is orginal, and while not a brown brass color, it is tinted more than a new bulb...
ARRRGGG!!!
Well... everything is good again...
Thanks for the tips,
Tom De