Chrysler Repair: Chrylser code P1698, chrysler cirrus lxi, powertrain control module

Question
Hi, I have a 1996 Chrysler Cirrus LXI with a 2.5 engine. 79000 miles.  I have a problem that the check engine light comes on quite often. When I take it to the gas station they put on the analyzer and it shows a code of P1698. They reset the computer and sometimes the light comes back the next day, or 3 months later. Recently it has been coming on every two hundred miles. Of course, the inspection is due next month. I just recently changed the ignition switch and the TCM relay. What could I check for next? Otherwise the car drives and performs fine. Thanks

Answer
Hi Ed,
The 1698 code means either that there is no digital data communication from the the transmission controller OR from the body controller that is being received at the powertrain control module.  An analyzer that read "hex" codes would distinguish which, the former being a 60 the latter a 61 hex code. Without a sophisticated diagnostic box about the only thing an amateur can do is shake the harnesses at those three controllers to see if you can induce an interruption that causes the light to come on in the case where it was a simple electrical wire discontinuity as the cause. With a diagnotic box the actual electrical characteristics of what is going on as shown on the data bus wires can be performed that might reveal which component is failing and why if it is not a wire problem.
I can give you the pin numbers at all three of those modules so that you could do a continuity check/harness shake test if you have an ohmmeter or continuity checker and would like to get into it. Otherwise trying to get a good referral to a tune-up mechanic who is familiar with the Chrysler system and has the test tools is the only alternative that will get the answer with the minimum of costs. It is not something that you want to try solving by throwing parts at it.
Let me know how I can be of futher help.
Roland