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The flashing D or R when put it gear usually means that the transmission thinks the throttle signal or your engine RPM'S are to high, normally over 900 RPMS it will not go into gear and you will get the flashing. This is a safety feature so it does not go into gear at that high rpm as it can damage the drive shaft. If you have a high idle switch make sure it is turned down and the cruise is off. Beyond that it could be a wiring or cable issue with the TPS sensor. I would check the cable in the engine compartment and make sure it is still attached. Normally on these older units that are mechanical the TPS body is located above the engine throttle linkage. Most RV'S do have access in the rear to get to the top of the engine. IF that looks good you might have to get a good mobile chassis RV company to come in and see what is going on..... Hope this helps some..... Robert
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