no forward is commonly a broken band. This is applied in D first and second. Box out job. Hold the lever slightly out of drive until the lights flash and you will get third. If you can manage to keep the lever off position till about 30 mph it can be released into D and then go on to 4th. Alternatively unplug trans computer in N then it will drive in D (third) Shift interlock will prevent lever moving from park with computer unplugged.
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