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Aw71 overdrive sequence

Marvelous3

Who engineered this?
Joined
Nov 12, 2002
Location
Atlanta
So I currently have the orange arrow in the dash staring at me. Lovely.

I?ve replaced the overdrive solenoid and relay but still no overdrive. My understanding is that the solenoid needs to get energized in order for 4th gear to work. So does it go power on, relay clicks over, powers solenoid? If I push the button on the shifter I can?t hear the relay click.
 
The default position for the relay is "send power to the solenoid". Solenoid opens, fluid flow is enabled, OD should work. This assumes the solenoid works, nothing else is blocking the fluid flow, and the OD valves and parts themselves aren't shot.

Hitting the button toggles and latches the relay in the "off" position, sending power to the light instead. Solenoid closes, fluid flow is cut off, OD disengages.

Hitting the button un-latches the relay, which returns to the default position... light off, solenoid open.

When you turn the car off, the relay automatically returns to the default position.

odd.gif
 
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Left of the glove box. Sometimes a nice whack in the area between the box and dash vents will wake it up.
 
Any idea where the relay ground is located?

I think it grounds to one of the large screws behind the center console face panel. I have one of the OD harnesses out in my shop.

I checked the harness and the ground coming out of the relay connector is only 4 inches long. It has a ring connector on it for the 6 mm ground bolts that go into the dash structure. It definitely grounds right behind that face panel.
 
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I think it grounds to one of the large screws behind the center console face panel. I have one of the OD harnesses out in my shop.

I checked the harness and the ground coming out of the relay connector is only 4 inches long. It has a ring connector on it for the 6 mm ground bolts that go into the dash structure. It definitely grounds right behind that face panel.

Okay great. Green book made it look like that but that?s good confirmation.

I?m thinking that either the ground wire is loose or the wire down to the solenoid is funky. Hate laying underneath this car.
 
I think you have another bad relay. As mentioned above, the default position for the relay supplies power to the solenoid. When you push the button the relay switches power to the dash light. If the dash light comes on when you turn the key on, the relay is stuck in the off position.
 
I hesitate here, because with an AW-71 on a 240, you've got a 82-85 Turbo, back when the relays worked opposite those of the later years. But the sig shows late model 240s and lots of mods, so could be an AW-70 if original using the newer relay. My little experience has those relays white vs the older 1s in orange. The white 1s had a very tiny foil trace in the solenoid circuit that could blow before the fuse if the solenoid wire under the car rubbed through on the transmission housing.

odrelay.jpg


The ancient pic above attempts to show a jumper wire fixing the open circuit board foil.
 
If you aren't getting the relay latching when you press the button. You'll also want to use a test light and make sure the button is pulsing the relay with 12v. If it is then the issue is in the relay.
 
I hesitate here, because with an AW-71 on a 240, you've got a 82-85 Turbo, back when the relays worked opposite those of the later years. But the sig shows late model 240s and lots of mods, so could be an AW-70 if original using the newer relay. My little experience has those relays white vs the older 1s in orange. The white 1s had a very tiny foil trace in the solenoid circuit that could blow before the fuse if the solenoid wire under the car rubbed through on the transmission housing.

odrelay.jpg


The ancient pic above attempts to show a jumper wire fixing the open circuit board foil.

Sorry, car was originally an aw70 car that got an aw71L with the turbo conversion. The wiring is all the same as far as the green book shows.
 
My apologies. The difference is in the cluster and internal relay wiring for the OD-OFF lamp, not the harness wiring, so it makes a difference what year car the post is about. The difference isn't between AW-70 and AW-71L -- the transmissions work the same; solenoid must be energized to dump the hydraulic pressure inhibiting overdrive.

I'd do what Dave suggests. Put your test lamp on the relay terminals. The gray wire to relay-86 should have battery on it when you push the button. However the relay should start out with initial key on delivering battery to relay-87, and only interrupt that when you toggle the relay with the push button. So I think Ian has a good guess that the relay itself is toast if you get battery at 15 and not at 87. Or your ground is missing ... check for NO battery at relay 31. Test light is your path to the truth.

But watch out for the older green books. The detail shown in the relay internals is drawn wrong for the older configuration where the lamp is returned to ground in the cluster. It shows 87 and 87A as the same circuit, but they are separate in the early relays. Get the p/n of the relay you have next time you're in there.
 
Art,

The relay that came out is an old Volvo white relay. Pn 3523804. When I pull the relay out of the white case it doesn’t look broken per say. Some corrosion maybe on the back. The replacement relay I got for it is one of those No name white replacements.


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Okay so if I take the old relay - with the cover taken off - and turn the car on the relay doesn’t kick over. If I then use my hand to push the contacts over the dash light stays illuminated.
 
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Whatever you do, don't assume new parts actually work. No joke. Read the 240 no spark thread. I'm running into this way more often these days. I don't trust anything from any manufacturer anymore without first testing the part. You don't want to spend 3.5 hours putting your 240 heater case all back together only to find the new blower motor has excessive shaft play or runs backwards.
 
So, may I assume this is your microsquirt injected '91 240 using the original overdrive harness and cluster? It just doesn't make sense to me that you can manually hold the clapper down on the relay to light up the arrow on the dash. The 3523804 I have is a Hella relay with an Elmos chip doing the alternate action logic. 87 and 87a are the same circuit, which would be bridged to switched battery with the clapper held down, activating the solenoid.

Best find that test light and check what you have on the relay terminals. Start with 15. If you have nothing there, check fuse 11. That's the only way I see you lighting that dash arrow by holding the clapper down.
 
Yes, it’s always the ducking megasquirt car that does dumb **** like this. I don’t know why it can’t just break like a normal Volvo.
 
-- the transmissions work the same; solenoid must be energized to dump the hydraulic pressure inhibiting overdrive.
And here I thought the energized solenoid allowed fluid to pass, enabling overdrive. :-P

And, y'know... the OD solenoid bypass plates for those "always-on" types.

014228862_1-390f3132f711651ac1369f8ee69fd53d-360x466.png


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^If the trans mount is oil soaked bouncy jell-o or there's oil all over the tunnel from a leaky engine or trans tailshaft bushing....
...or someone didn't reinstall the bullet connector back in the clip on the trans.

But the hot weather cars and rotting wire insulation also doesn't help much, nor windshield leaks/cabin moisture for the electrical or solder joint issues on the relay or hot salt air florida or atlanta climate.

I've seen the fluid passage blocked in the trans from some numb-skull not putting on the mask/glasses or face shield and respirator and blowing the debris out from around the solenoid and scrubbing it clean around it prior to removal and allowing debris to fall in the upward facing holes...
 
One of the grey wires was getting pinched at the shifter next to the neutral safety switch pizza slice. I know my brother in law had someone work on the shifter and it looks like when they put all the wires back in they shoved it in so when the shifter when into park it was pinching the grey wire. Over time it wore through the plastic sheething. Electrical tape it is I guess.
 
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