Need some help from the M46 OD guys. This is related to a post I wrote yesterday about the OD functioning intermittently on my 81 M46. Duane suggested that I get under the car with VOM set to ohms, shifter in fourth. Check red wire to ground. Wiggle shifter. If continuity is not maintained, 4th gear switch is bad.

Right now I've got the battery out of the car. I'm assuming the battery needs to be installed with the key on, and the red wire connected to switch for the test? I know these are beginner questions so thanks for the patience and extra detail.

Thanks to everyone for all the help given,
Doug C. 81 242 Brick on Blocks, stock; 86 240, 129k, smashed quarter panel.

Here what I know so far. These four tests were done with the battery out of the car.

There is continuity between the OD relay plug terminals 85 and 15 when in fourth gear but not in the other gears. Pressing the OD button during the test doesn't change the results.

There is continuity between the OD relay plug terminal 85 and chassis ground when in fourth gear but not in the other gears. Pressing the OD button during the test doesn't change the results.

There is continuity from the fourth gear switch on the side of the transmission to transmission case in fourth gear but not in the other gears.

The OD solenoid gives a consistent click when 12v are applied.

What is the next step to determine what is causing me to have to press the OD button three or four times in order to get it to shift??
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Thanks to everyone for all the help given, Doug C. 81 242 Brick on Blocks, stock; 86 240, 129K, pictured in Rolling once, now has smashed left quarter panel thanks to the driver of an F150. Daughter safe in her Volvo.

Thanks a lot for all the advice. I may have hit paydirt. I added a suggested test between relay socket pins 86 (center one) and 15. There is intermittent continuity between these two pins. With the VOM connected to these two pins, the button on the shifter sometimes causes a change in continuity and sometimes it does not. With the VOM set to squawk when it finds continuity, it sometimes takes five or more pushes of the button on the shifter to make it stop sounding or start sounding. The button on the shifter is more consistent in first gear than in fourth, but doesn't work consistently in any gear. To me this says that the problem is most likely in the gearshift button or its wiring. Am I correct? If so, how does the gearshift know come apart without breaking anything?

I don't want to put the battery in the car right now to see again when the light on the dash goes on and off because the manifold is out of the car and lots of wires and stuff are just hanging there under the hood. So I'll wait for that test and do it later if necessary.

The other tests I've done are listed again below.

There is continuity between the OD relay socket terminals 85 and 15 when in fourth gear but not in the other gears. Pressing the OD button during the test doesn't change the results.

There is continuity between the OD relay socket terminal 85 and chassis ground when in fourth gear but not in the other gears. Pressing the OD button during the test doesn't change the results.

There is continuity from the fourth gear switch on the side of the transmission to transmission case in fourth gear but not in the other gears.

The OD solenoid gives a consistent click when 12v are applied.

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Thanks to everyone for all the help given, Doug C. 81 242 Brick on Blocks, stock; 86 240, 129K, pictured in Rolling once, now has smashed left quarter panel thanks to the driver of an F150. Daughter safe in her Volvo.

Paydirt will be either the switch, or the wires inside where they come out from under the boot.

The "cap" prys out of the top of the shifter. The button will then be able to be pulled up and out for tests outside the shifter.

Pull up the carpet and the boot before pulling the button loose. Feeding the wires from below helps all come apart.

Duane

This is correct operation:

"There is continuity between the OD relay plug terminal 85 and chassis ground when in fourth gear but not in the other gears. Pressing the OD button during the test doesn't change the results."

I have a question about the following:

"There is continuity between the OD relay plug terminals 85 and 15 when in fourth gear but not in the other gears. Pressing the OD button during the test doesn't change the results."

I'm confused a bit, as far as the actual wiring goes you shouldn't have continuity between these two points, are you removing the relay before taking these readings? The OD engagement switch is between pins 15 (this pin should also have +12v with ignition turned on) and 86 (I think it's 86) and with the relay removed you should have no continuity (infinate ohms) until the switch on the shifter is pushed then you should have continuity (< 1 ohm). What gear the transmission is in should have no bearing on what happens on these two wires.

Justin

All the test at the relay socket were done with the relay removed. Your suggestion regarding 86 and 15 proved helpful. There is inconsistent continuity between these two terminals. The button on the shifter sometimes changes the continuity and sometimes it doesn't. Often four or five pushes on the button are required before the button functions. Thanks for the help. Conclusion at this point is the button or its wires are bad. I appreciate all the help. I'll replace or repair and post results.
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Thanks to everyone for all the help given, Doug C. 81 242 Brick on Blocks, stock; 86 240, 129K, pictured in Rolling once, now has smashed left quarter panel thanks to the driver of an F150. Daughter safe in her Volvo.

"And it might still be a bad solder connection in the solenoid..."

...should say...

"And it might still be a bad solder connection in the relay..."
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Don Foster (near Cape Cod, MA)

"What is the next step to determine what is causing me to have to press the OD button three or four times in order to get it to shift?"

Does the green light go on-off each time you press the button (regardless of whether or not OD engages)?

If so, then the problem is likely a bad solenoid, bad sonnection, or bad solenoid ground. (And it might still be a bad solder connection in the solenoid.)

If not, then it might be a bad solenoid solder connection, or the wires to the button, or the tiny tab connectors AT the button might be flakey.

Is the tranny full of oil?
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Don Foster (near Cape Cod, MA)

"I'm assuming the battery needs to be installed with the key on, and the red wire connected to switch for the test?"

Not for a continuity test. Check continuity to ground at the switch (wire unplugged) as you or a helper shifts the tranny in 'n outta fourth gear. The switch should show continuity (0 ohms) to the tranny case in fourth and infinite ohms in any other gear.

An alternative approach is to jump the wire to ground, which "enables" the OD relay constantly. This is just as if the switch had properly switched. Then drive the car, and see if the OD problem persists or is gone.

Be very careful to use OD only in fourth gear. In particular, be aware that OD can attempt to engage in reverse, and it may do serious damage to itself if it engages. Thus, be sure OD is disengaged except in fourth for your test.
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Don Foster (near Cape Cod, MA)

It passes the first test. There is continuity from the fourth gear switch to ground in fourth gear but infinite ohms in any other gear. I also tested for continuity from the end of the red wire that goes to the fourth gear switch to ground and there was none. I'm thinking this means that at the moment of the test, the wire was not shorting out to ground. (It looks like it is well sheathed. The third test I've done is apply 12v to the solenoid and I do hear a consistent click each time I do this. As far as I know, that leaves the switch in the shift knob or the relay. Is this assumption correct? Any suggestions of further tests to solve problem??
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Thanks to everyone for all the help given, Doug C. 81 242 Brick on Blocks, stock; 86 240, 129K, pictured in Rolling once, now has smashed left quarter panel thanks to the driver of an F150. Daughter safe in her Volvo.

The red wire should mimic the 4th gear switch when tested from the relay socket. Continuity when in 4th, infinite ohms in any other gear. There is a connector in the red wire under the vehicle above the tranny. It is shared with the reverse light wire bundle. You might want to check that one.

Duane

Have you resoldered your OD relay?

$0, 15 minutes, no risk, clean 'n easy work. If it helps nothing, you're out nothing. It's a great diagnostic at zero risk, zero cosr, and a reaonably high chance of solving the problem.
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Don Foster (near Cape Cod, MA)

I've never soldered anything that small, but I'd like to learn. Any recommendations on right soldering iron? I'm afraid I'd fry it.
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Thanks to everyone for all the help given, Doug C. 81 242 Brick on Blocks, stock; 86 240, 129K, pictured in Rolling once, now has smashed left quarter panel thanks to the driver of an F150. Daughter safe in her Volvo.

I use a small iron (20 Watts, more or less) for the ordinary connections, such as the leads for resistors, ICs, transistors, etc. I use a gun for the heavier connections( 150-250 Watts, or so), such as the spade lugs and the actual relay lugs. The heavier connections will "suck" the heat away from a small iron too quickly to allow the temperature to rise enough so the solder melts. But with a dun, you must work quickly. The solder connection gets hot quickly.

It takes practice -- I've been soldering since I was around 10 years old, and have probably a dozen irons of different sizes and types for different applications, and four guns of different sizes.

Be sure you use electronics solder, not plumbing solder.

For casual uses, you can probably buy what you need at Radio Shack.

And restoring ONE expensive Volvo relay will offset the cost of the tools you buy at Radio Shack -- and then every relay after that is "free."

The tutorial below, shamlessly copied from a Heathkit manual, offers good advice for the "newby" solderer.

Nice information. Thanks!
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Thanks to everyone for all the help given, Doug C. 81 242 Brick on Blocks, stock; 86 240, 129K, pictured in Rolling once, now has smashed left quarter panel thanks to the driver of an F150. Daughter safe in her Volvo.

Geeze, Don, you trying to make me feel old? I haven't seen Heathkit soldering instructions since, well, never mind! ;-)

Justin

It reassures me that you have seen Heathkit instructions. Even knowing about Heathkit means you're part of the "inner circle."

My first Heathkit, a Christmas present from my father when I was 10 or 11, was a 5" oscilloscope. My mother gave me a Weller soldering gun. I had that sucker built by the next day, and properly repaired and working the next day. Yes, being a "ready fire aim" guy, I mis-wired something and smoked a pot. (That's different from smoking pot, which mighta come later.)

The 'scope went to a local vocational high school some years back (still working) and the soldering gun is in my tool box, also still working.

I believe I have 15-20 Heathkits kicking around, most working properly, including a weather station, ignition analyzer, ignition scope, exhaust gas analyzer....

...and a boatload of electronic test equipment.

I never went for their TVs, stereos, or ham gear, but I did buy an RC model airplane from them (A Delta kit, I think).

Even though Heath is long outta the electronic kit business, I believe they're still around selling instructional systems, or some such.
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Don Foster (near Cape Cod, MA)

I would think 1 20-30 watt iron with a fine (1/8" or so) tip would do the trick. I have a temperature controlled soldering station so I just dial in the tip temp I want! Soldering guns will often get too hot and actualy lift pads and traces from the board if you leave it on too long.

Good luck,

Justin

The wires going up into the shift lever are prone to being pinched/broken/shorted so as your problem is intermittent it might be a good idea to pull up the shift boot and eyeball them. The shift lever I got from the boneyard for mine had these wires pinched and one broken at the spot where they go under the boot. It's also possible that they have become unplugged from the switch, the wires have connectors that push on the lugs on the OD switch so if you've been yanking around on any of those wires one might have come undone.

You can check OD switch circuit continuity between pins 85 and 15 (I think on 83 anyway...), put meter there and operate switch and at the same time hold switch in and wiggle the shifter around to see if there is any change.

Justin B.