Chrysler Repair: Occasional transmission Jerk: 97 Caravan, liter engine, grand caravan

Question
I have a 1997 Grand Caravan with  3.8 liter engine and about 150,000 miles.  On occasion I will be cruising along at 60mph and or so and the van will jerk real hard and the speedometer and tachometer gauges will fluctuate erratically and the check engine light will come on and then a second later the light will go off and the van will act like nothing ever happened.  I think it is some sort of transmission problem and I don't know how serious it is and if I should start thinking about major repairs or getting another vehicle soon.  A jerk every now and then doesn't bother me if that is all it is.  This jerk was first noticed several months ago and now seems to happen more often and this is once every couple of weeks when traveling at highway speeds.  This is not notices while driving around town.  Thanks for your help and advice. Brandon

Answer
Hi Brandon,
There are so many possibilities that the best approach is to do a readout of the powertrain and transmission controller to see if they have logged a fault code in their memories that will tell what they detect as the cause. In '97 it was likely that the only way to get a readout was to plug in a code reader to the socket under the dash by the steering column. An Autozone parts store will often do it for free or an independent shop will do it for around $40. Once you get the 4-digit fault code number(s) write back and we'll get an idea what is the problem from the manuals.
There is an outside chance, though not likely, that any engine only codes might appear by using the ignition key "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the check engine light to see if it begins to flash, pause, flash, etc. Count the flashes before each pause. Then repeat to be sure of an accurate count. Nominally the '96 year was the last to have this feature (until later years when the numbers would show up in the odometer window), but there is no harm in trying.
Could it be that your ignition switch is flaky? If you have a lot of keys hanging on it that can cause an older switch to fail momentarily.
Roland