My new to me 1996 E300D has an intermittent flashing glow plug light issue. The glow plugs and harness were replaced by the MB Dealer withing the last 2500 miles. Car will throw a p0380 code. I have read in the forums about checking the resistance but am unsure where to make the measurement in my car. I have the shop manual CD from MB but it reads like hieroglyphics to me. Any other thoughts on what to check? I do not like ignoring the check engine light or the flashing glow plug light. I should mention that the car starts easily every time and appears to run fine with 27 mpg city and 33-35 mpg highway.