Chrysler Repair: Code 0420, 1698: 99 Cirrus, 4 digit numbers, oxygen sensors


Question
QUESTION: I just purchased '99 Chrysler Cirrus. Each afternoon all of the gauges stop working as do the electric door locks. The car runs fine in this condition. Mornings and evenings everything works normally. I suspect a heat sensitive relay. There are no known bad fuses. I checked the other posts but couldn't find this particular condition.

ANSWER: let me study the wiring diagrams and be back shortly with the answer.

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QUESTION: Also, the check engine light is on

ANSWER: About the check engine light: turn the ignition key:"on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the odometer window to see the mileage reading change to show 4-digit numbers preceded by a P. Let me know what you find and we'll go from there.
Roland

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QUESTION: It's that time of day an gauges are dead, including odometer. Auto supply shop pulled codes P1698 (twice) and P0420

Answer
Hi John,
the 1698 says that the communication for digital messages from the transmission computer to the engine computer and rest of the digital bus is not happening. It could be the digital bus wires (a twisted pair) have an open or short, or fuse 3 under the hood or fuse 11 in the cabin is flakey as I described earlier. Fuse 11 is also involved with operting the tcm. So start by checking the fuses, particularly 11. The loss of the speedometer would be explained by that code but not all the other gauges if they all go out as you described earlier.  
The 0420 says that the catalytic converter or the oxygen sensors on the exhaust stream that comes from the rear cylinder bank is not doing its job. So check the converter, the upstream and down stream oxygen sensors, and also check for an exhaust leak along that pathway.
Roland
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