Chrysler Repair: 91 transmission in limp-mode, solenoid pack, chrysler imperial

Question
i am currently working on a 1991 chrysler imperial, 3.0 v6, 4 speed automatic. Cruising the freeway it will shift into a lower gear and back with no perticular pattern, just randomly. no codes. serviced recently. was thinking the shift solenoid pack might be going bad or should i look to the trans computer in greater depth first?

Answer
Hi Lance,
When you say "no codes" I presume you mean via the ignition switch and check engine light flashing. That code readout is only for engine controller issues. The transmission fault codes are only accessible via a blue color 'data link connector' socket located under the instrument panel near the fuse box/left side cowl panel. It is readout by connection to a Chrysler DRB II at a dealer or a Snap-on OBD-I vintage reader, which has the corresponding blue data link connector plug. The fault codes are two digit numbers, similar to those of the engine, so you need to be sure you access the correct socket and have the instrument set up to readout the transmission controller memory. Once you have the code(s) let me know what they are and we can go from there. Whenever the trans spontaneously shifts into 2nd gear it is called limp in mode and a code is set. The only simple explanation would be a failure of the transmission control relay located in the power box under the hood, so try switching that out with another relay with the same part number. The relay is in position 6 in the power distribution box under hood, the middle one of three at the end of the box.
Roland
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Roland