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Overdrive Question

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stretchit2

stretchit2

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Fellas (& Ladies of course)

Over the years I have replaced virtually evey component of my Overdrive system: Switches, Relays, Solenoid, you name. For about the past year it has been working flawlessly. Last Saturday I was out on a drive and I noticed that the when I switched it to off (and gave it the requisite pop of the throttle) the overdrive did not disengage. Hah, so I pulled over shut the car off restarted her and headed off. 1,2,3,4 hit the overdrive switch it works perfectly, then I turn the switch off, pop the throttle.....nothing. Several more attempts same result (yes, I may be insane). Does anyone have an opinion as to which component may have failed. BTW, when I am in neutral and I move the gear shift lever back and forth I hear the solenoid. I'm guessing switch, mostly because it is the easiset part to repair.

What say you?

Jeff
 
Most suspect to me, would be the throttle position switch. For an easy test, put both (2) of the wires under one (1) terminal, and go for a drive to test the function.
 
The TPS would be my guess too. The TPS is a set of points and, like any points, they can stick. Check as Randy suggested, then check the setting and, if necessary, you can carefully open it up and file--and clean--the points.
 
I had a problem that caused the overdrive mechanism to hang up in the on position. I had to reach under and pull down the lever on the right side of the tranny. See if this lever can be pulled down once the solenoid is de-energized. Turns out the rubber bump stop below the solenoid plunger in the box on the left side of the tranny had hardened and crumbled. Seems unlikey but all I could figure is that the additional travel allowed the plunger to pull up harder to the point it jammed in the full up position. Since fixing I have had no trouble.
 
The arm on the throttle position switch clamps on to the shaft that goes through the switch. If the bolt holding that clamp has loosened over time, depressing the throttle will not move the shaft and the switch won't work. Easy to check though: just operate the throttle linkage at the carbs and make sure that the shaft is turning. If it is turning, it's not too difficult to check its operation if you have an ohm meter. I can't at the moment remember if it's supposed to be continuous when the pedal is up or when the pedal is down.
 
If it's not the TPS, on mine the overdrive cone clutch was worn and the sliding element would go to far and get stuck. But I agree with the TPS since it disengages when you turn it off. I had to use reverse to disengage.
 
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