Re: Strange Overdrive Noise

Posted by HH56 On 2008/10/7 19:20:54

The relay seems to have been eliminated with your last description so all that's left electrically is solenoid. When you are at speed, the relay closes between term 1 & 4, energizing pull in coil and light. When you let off gas, the solenoid is able to move so one set of contacts in solenoid opens pull in coil circuit and another the light circuit. The relay stays energized until you either kick down out of OD or go below speed so it must not be causing the noise.

What I'm concerned about is the burned solenoid. The only way I can see that much damage is if the wrong voltage was applied or if the pull in contacts are not opening allowing that coil to stay energized constantly--which it's not designed to do.

You could follow the procedure in econo drive manual to pull the solenoid, leave everything connected but ground the solenoid case (a heavy wire & tight connection or maybe a jumper cable) then energize everything by grounding the OD wire at governor. The plunger should snap out one time, and stay. Moving the gas pedal to kickdown position should drop everything out and if governor still grounded, releasing gas will cause it to snap out again. If no noise, all is well. Then put back in and repeat the governor ground. If noise, then something is binding or preventing travel. Then would be a good time to measure the actual current draw on pull in coil. If it still was drawing current when engaged, that would not be good. A few months ago another poster was having problems with his OD solenoid, and I believe he found a different shaft length on his replacement.

In addition, there are a couple of cautions in the OD manual regarding the solenoid spacer installed correctly and to make sure the gaskets proper thickness. If either of those were wrong, I could see it causing an issue.