Packard Forum Index » Pre-War (1899-1942)

I was driving on back roads. I never had the overdrive cable pulled out but i noticed the areo drive light on the dash flickering around 28 and the light would come on around 30mph. is this normal?

If the knob is pulled out and lockout switch is working it will be open and the relay will not energize so light should never come on but if the knob is pushed in the light will come on when the governor reaches whatever speed it is set for and closes its contacts. The light is to tell you overdrive is active, solenoid is prepped and OD can be engaged by lifting your foot off the accelerator for a moment.




The light should not flicker though so there could be a bad connection or some dirty contacts in the solenoid, relay, or one of the switches in series from the governor. A more common issue is the lockout switch could have a worn plunger end and is not being pushed up far enough when the knob is pushed in for a solid switch engagement. Vibration could be causing the flicker because the switch is on the edge between closing and opening.

29tons, and this refers to a tractor trailer, a canal boat? This wear groove HH56 well describes can be remedied with industrial grade epoxy, Ace Hardware. etc., built up to the original contour, allowed to fully cure.

Meanwhile, double check all overdrive wires for secure connections, good ground, and if your car hasn't a replacement wiring harness, frayed wires. Most OD maladies are electrical. While so focused, tho' not your problem, check your transmission and overdrive fluid levels separately, and if needed, top off separately.

Some of us leave our OD knob pushed in all the time, as the small amount of city driving out of mountainous terrain exacts but little additional brake wear, and makes shifting at low speeds even easier. Obviously, descending long mountain roads, you'll want to pull out your OD knob, disengage, to have engine braking. You do get engine braking in OD in flat realms at cruising speed, but not as much since your overall gear ratio is numerically lower; taller.