Chrysler Repair: P1698: 99 Avenger/Sebring Sedan, powertrain control module, transmission control module

Question
1999 Dodge Avenger V6.  I had the engine replaced very recently--2 weeks ago.  Within 200 miles the P1698 code came up via CEL. The mechanic thought it was a relay and replaced that, cleared the code.  The CEL lit up again with the same code within 50 miles.  I cleared it again, however since it is my daily driver, I don't want to get stuck. Any ideas on what he can check?  Was there something the engine swap caused or missed?  Thanx  Jo

Answer
Hi Joann,
The P1698 code means that no digital data signal is being received by the powertrain control module from the transmission control module, both of which are located in front of the battery next to one another.  The manual says to check the digital data wires between the transmission control module and the rest of the system using the Chrysler diagnostic readout box. But if you don't have access to that device, then I think you can do the same thing by removing the plugs of the pcm and tcm and measuring for continuity (near 0 resistance) between pin 44 of the transmission's plug and pin '28' on the 12-pin data link plug under the dash to the right of the steering column and/or pin 5 of the powertrain controller plug (white/yellow wires).
Then check the resistance between pin 45 of the trans controller plug and pin 27 of the data link connector under the dash and/or pin 6 of the powertrain controller plug (black/yellow wires).
Check the condition of the pins/sockets of all those interconnections and that the wires are not shorted to ground.
If the continuity between the transmission and the powertrain and data link plug wires checks to be ok, then according to the manual the trans controller should be replaced. However, you could also try shaking the wires to all the plugs when everything is reconnected and the engine is running to see if by so doing causes the check engine light to come 'on' which would suggest a problem with a wire in the harness being shaken.
My pin numbers are based on the '00 manual and thus pin 5 could actually be 60 and pin 6 could be 59 on your '99 model; but in any case the wires in question are the only ones that are twisted together, so just look for such wires at the respective plugs. If you didn't have this problem before the exchange then I suspect it is wiring/pin interconnection problem rather than a need to replace the trans controller proper. I would expect that when the light come on that you would notice the transmission might shift gears unexpectedly or some other misbehavior.
Roland