Hello. My 1987 240 Auto tranny overdrive was not working. Tested electric. Was getting 12Volts to solenoid so wiring & relay were good. Fiquring it had to be a bad solenoid I ordered a new one from FCP Groton. After putting it in still no overdrive ! So I dremeled out between the holes on old/bad solenoid and put that in and bingo now I have overdrive. Guessing the FCP solenoid was defective I tested it and it clicked when 12 volts was put to it yet when tested with an ohmmeter it did not have 13 ohmns resistance as a properly working one should. It read 0. Question is if a solenoid clicks when 12 volts is applyed to it and yet does not have proper 13 ohms resistance when it is measured why didn't it work when on car ?? I am curious about this matter. By the way FCP is taking back the defective solenoid. Also by the way I think I will leave dremeled out old one on car. It is a real big pain to take on & off solenoid. I do not have a lift so work on my back underneath car. I have come to the conclusion that best way to deal with overdrive problems if they are electric is to wire straight from fuse panel direct to solenoid with perhaps a switch in between(saves troubleshooting pesky OD button,OD relay,wiring problems) and if problem is solenoid itself then the dremeling out procedure works fine(saves rather pricey cost of a new solenoid). Very best to all.

Hi there,

I think your FCP solenoid is OK. Your ohmmeter is hosed or on the wrong scale.

If it truly measured zero ohms on a good meter, it would smoke the lead wire when you connnected 12V instead of obediently clicking. Try measuring something else with your ohmmeter to verify it. A good example might be the heater in your lambda sond - it is easy to reach, and the approximate cold and hot resistances are listed in the FAQ.

Good solenoids or not, I agree that spot under the car is not a nice place to spend a lot of time. I expect if I live a good life on earth there will be a nice lift I can use in the afterlife.
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Art Benstein near Baltimore

Numerous times in the past I have installed brand new solenoids only to have them not work. These were all brand new Volvo parts. Every one of them eventually came around and started working. Now why they do this is the real mystery, I don't know if it is a matter of bleeding them out or what but I have seen plenty of them do this. Like you, I pulled it back out, went over to the battery, put the case on the negative post and touched the lead to the positive post and everytime they would make a nice loud click. I now have a tester in the shop and it is just part of my diagnostic tool kit on overdrives. If I put in the bypassed tester solenoid and I have overdrive then it needs a new solenoid and if the new solenoid does not work right out of the gate then I simply run it until it does.

Mark

Can you clarify on your solenoid rester?

Is it just a known good solenoid?
When you say bypassed, do you install and power it direct from the battery?

Thanks in advance.

The tester is just an old solenoid that I took the dremel to. When I say by passed I am referring to defeating the electrical portion of the solenoid by grinding a passage from one hole to the next in it.

Mark

That is an interesting account. It reminds me of the many shadetree stories related here on this forum suggesting the fix for non-working overdrives with nicely clicking solenoids is a thorough cleaning or even a fluid change.

The variable I wonder about is the strong liklihood of an intermittent electrical path beginning at the shifter box up to and including the internal connection in the old solenoid's windings; but mostly at the bullet terminal. A static test, i.e. "I have 12V" could miss a problem you'd wiggle the wiring to expose.
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Art Benstein near Baltimore

I doubt the likelyhood of an electrical open in the circuit as I have installed a few of them and had them not work and did nothing to them other than drive them on the rack while cycling the solenoid on and off. They all eventually started working and none of them have ever boomeranged. You'd think that if it was some nebulous open circuit somewhere in the wiring that 1. if it was indeed at the bullet that disconnecting the old and reconnecting the new would've rectified it and the new solenoid would've worked from the get go or 2. that if it was a case of an intermittant open that it would rear it's ugly little head down the road and boomerang on me. I really have not seen either one of these things happen. But like I said, I do not really have a good explanation for it either so you never know.

Mark

Oh, I agree. The electrical variable I mention is in the subject post of this thread, a diagnostic owner made, not your experience as a professional replacing a confirmed non-functioning fluid switch. I trust you are well skilled at separating the electrical from the hydraulic symptoms before actually laying hands on your 12mm wrench. Much easier standing up, too.

The mysterious need for a new solenoid to acclimate itself to its new fluid environment would suggest a bit of clotting in the machine's life blood. Though I haven't any direct experience with the delayed action after replacement, I've seen the passages through the casting to the valve body are long and thin, and separately found the waste oil after a high-mile tranfusion to be laden with the clutch particles of too many ignored fluid services. Just another guess at the behavior you note.
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Art Benstein near Baltimore

I have often entertained a theory much akin to what you describe, I have in the past had success with blowing compressed air through stubborn solenoids. Pour ATF on the passages and activate the solenoid a few times, while also feathering a little compressed air through them as well. A couple of well respected trans rebuild shops in my area swear that if you get ATF hot enough it will actually gell. In fact they just package all of their rebuilds with a product that they refer to as "cooler douche". The stuff works very well and I really don't want to know what is in it because I have to think that it is some pretty nasty stuff to cut through the crud that it does.

Being able to stand up and do a solenoid is a huge advantage for sure but a flex-head gear wrench in 12mm is really awesome as well. One of those tools that when you buy it and use it you wonder "where have you been all of my life"

Mark