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Old 06-19-2005, 09:38 PM   #1
Donny
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Default What actually tells the OD to engage (AW71)?

I ask this because I just changed the O2 last night on my 765 and now today the OD is craping out on me. This morning it didn't engage for about 20 minutes. I guess it could just be coincidence that it decided to go the next morning.

The relay is working, I actually cleaned the contacts up a little and the arrow light comes on and off with the switch. I can hear it operating in the cab.
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Old 06-19-2005, 10:13 PM   #2
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i bet the od solenoid is taking a crap. i just uded one off of some toyota tranny.
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Old 06-19-2005, 11:30 PM   #3
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Does sound like your relay is fine and that the wiring to the solenoid is good (as otherwise the dash light would not work). Odds are you need another solenoid, this is the same part used on all AW70/71 trans (240/700/900).
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Old 06-21-2005, 07:51 AM   #4
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I can't speak for all of them, but I find the overdrive on mine to be fascinating. It engages after 3rd gear, period. It completely ignores the switch, and even removal of the relay. It must be a conspiracy!
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Old 06-21-2005, 01:53 PM   #5
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Quote:
Originally Posted by foxtrapper
I can't speak for all of them, but I find the overdrive on mine to be fascinating. It engages after 3rd gear, period. It completely ignores the switch, and even removal of the relay. It must be a conspiracy!
The solenoid may have been modified into a permanent bypass position, or the it's simply stuck.
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Old 06-21-2005, 02:32 PM   #6
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Quote:
Originally Posted by Three Fat Tigers
Does sound like your relay is fine and that the wiring to the solenoid is good (as otherwise the dash light would not work). Odds are you need another solenoid, this is the same part used on all AW70/71 trans (240/700/900).
So the wiring that frequently goes bad would be the problem if the solenoid never engages? Since mine works after 20-30 minutes you think the solenoid is bad?
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Old 06-21-2005, 03:52 PM   #7
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Quote:
Originally Posted by Captain Reclino
So the wiring that frequently goes bad would be the problem if the solenoid never engages?
If the wiring was bad, then yes it would likely cause the solenoid to never engage. However if that were the case then the dash indicator light would not come on either as on you car this lamp grounds through the OD wiring and the solenoid itself.

Quote:
Originally Posted by Captain Reclino
Since mine works after 20-30 minutes you think the solenoid is bad?
Yes, from your description odds are the solenoid is bad, this is not to say it couldn't be something else such as a defect inside the transmission, but the odds favor the solenoid.

If you want to try a test: run a fused wire directly from the battery, down the transmission tunnel and connect to the solenoid wire. If the OD works right off the bat, then you do in fact have some sort of wiring/relay issue where insufficient amperage is getting through, at least when these parts are below operating temp.
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Old 06-21-2005, 04:30 PM   #8
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It could maybe be a sticky kickdown cable. Shoot some WD40 into it up at the top and let it sit for a few, never know, that happend to me and the car wouldnt get out of second.
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Old 06-21-2005, 05:20 PM   #9
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I have the same problem, where is it located?
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Old 06-21-2005, 06:14 PM   #10
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OD solenoid, go under at the drivers side, mounted on the side of the tranny facing down. Looks like a small lump on the side of the tranny, has a wire going from it. two 13mm bolts hold it on ( 13 or 14, cant remember). wire connects above its location, simple clip to another wire.
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Old 06-21-2005, 06:25 PM   #11
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For reference:
http://www.threefattigers.com/Protoc...eOutSide2c.jpg
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Old 06-21-2005, 08:30 PM   #12
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Awesome! thanks!
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Old 06-21-2005, 10:04 PM   #13
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The night before the OD started acting up I noticed the accellerator cable had gotten out of it's groove. It actually had been that way for a while, it slowly added LOTS of drag to my accellerator but it hapened gradually. Eventually I was like... something is really wrong with my accellerator cable. Once we fixed it I noticed a bit of slack on the kickdown cable at rest. I didn't think this was the problem because it does kick down. It just doesn't shift into OD. I will go try some spray on the cables, maybe some PB. I'll report back my findings.
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Old 06-21-2005, 10:44 PM   #14
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Nope. I was just hoping for a quick fix. I will just grab a few solenoids from the JY and swap em out. The car is kinda fun to drive without the OD anyway.
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Old 06-22-2005, 10:49 AM   #15
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Quote:
Originally Posted by Three Fat Tigers
The solenoid may have been modified into a permanent bypass position, or the it's simply stuck.
Nah, if it was simply stuck or permanently engaged it'd be working on 1st and 2nd as well.
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Old 06-22-2005, 02:28 PM   #16
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Quote:
Originally Posted by foxtrapper
Nah, if it was simply stuck or permanently engaged it'd be working on 1st and 2nd as well.
Not in an AW70 or 71.
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Old 06-23-2005, 09:29 AM   #17
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Quote:
Originally Posted by Three Fat Tigers
Not in an AW70 or 71.
Why do you say that? It's located after the main transmission. If it was stuck on as you claim, it would be engaged in all the gears.
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Old 06-23-2005, 02:21 PM   #18
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What you are describing is an 4 speed manual transmission with a J type OD, otherwise known as the M46. The subject here is an AW71 4 speed automatic, IMO "OD" is not really a correct nomenclature to apply to this transmission. On the AW71, the solenoid is normally on all the times unless you manually turn it off, so bypassing the solenoid, or a stuck open solenoid, will simply not allow you to manually turn off 4th gear (aka OD).
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Old 06-23-2005, 07:50 PM   #19
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Very impressively written! Unfortunately, it's completely wrong.

The ZF transmission is the 4 speed unit. The AW transmissions (both the 70 and 71) are conventional 3 speed planetary geartrain units. They are just like a Ford C-4, or a GM Turbo 350 in their 3 speed planetary geartrain design.

A separate overdrive is used by the AW71, and inhibited in operation to only third gear. This overdrive lives within the transmission case, but is distinct and separate from the rest of the transmission.

The electrical circuit to the overdrive solenoid on the transmission is not normally energized, it is normally off. It is only energized when the solenoid closes the contact, providing electrical power. This event only happens when the transmission is in third gear, and the shifter electrical switch is closed, causing the relay to close. Then, and only then, is electrical power provided to the overdrive solenoid, engaging it.

If the overdrive unit were to somehow "hang up" in the engaged mode, the transmission would no longer shift to four distinct gear ratios, but would engage only the conventional three, at the higher overdrive enhanced ratio. This would be most noticable in 1st gear, as it would be a much taller ratio, resulting in substantially slower acceleration.

I hope this information helps you to understand how these transmissions and overdrive units actually operate. Further information on this subject can be obtained from a factory service manual, wiring diagrams, and examination of the transmissions themselves.
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Old 06-23-2005, 09:06 PM   #20
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I assume you know how to read a factory wiring diagram?

If you will observe the power flow section below:


The force is strong with this one, but you are not a Jedi yet.

Last edited by Three Fat Tigers; 06-23-2005 at 09:09 PM..
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Old 06-24-2005, 10:38 AM   #21
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Quote:
Originally Posted by Three Fat Tigers
I assume you know how to read a factory wiring diagram?
Sure'nuff!

Oh, so close! But you still missed.

If all that happened was like your lil' ole red crayon showed, that overdrive would never disengage, and there's only be two shifts, with a real leggy 1st gear like I described. Reverse would be a real trip as well. But that isn't how it happens, is it?...

Darn that pesky transistor in the relay box and those dangling wires that you ignored! Those things keep that solenoid from engaging until the car's in third gear. Shucky darns, no power to the solenoid until then.

We're making progress though! You seem to have realized now that the AW71 isn't the fourspeed gearbox you claimed earlier, and you've figured out it really does have an overdrive. Pretty soon we'll have you up to speed on it!

For bonus points, see if you can find any problems in that diagram of yours that you scanned. I'll give you a hint for one of them, has to do with a series circuit.
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Old 06-24-2005, 11:32 AM   #22
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Quote:
Originally Posted by foxtrapper
If all that happened was like your lil' ole red crayon showed
That's not my red crayon, that is Volvo's red crayon. Ok... so in the face of documented proof that you are wrong you deny the facts. On the point about it not being a 4 speed, I am aware of the technical aspects of this transmission, and have been since long before you were born. You still cant deny it has 4 speeds, and can be referred to as a 4 speed transmission, maybe not technically, however I wasn't in super saiyan technical II mode when I responded at that point in this thread, perhaps you next will turn your attention to how I leave out the apostrophe in the word dont, just make sure your power level is at maximum if you hope to make a dent in my armor. You clearly have a bizarre understanding of how this transmission works, and I'm not very interested in damage control.


Suggestions:
Hey foxtrapper, why don't you go back to the brickboard which is where your accent is obviously from, or stfu, as you are obviously are a freaking idiot.


Ok so now somebody ban us both so I can get some sleep.
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Old 06-24-2005, 02:57 PM   #23
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I appologize TFT, I accidently gave you too much credit. Didn't mean to upset you by doing that, truly. I really thought that you'd traced the circuits yourself, thereby actually following them and thinking about them while you did it. I was really quite impressed.

I was hoping that with some nudging you'd have noticed that the ground side of the relay coil is switched by a transistor. I figured you missed that when doing the red lines, since it's not common and the significance of it is easily overlooked. For it means having juice at the coil won't activate it unless the ground switch is engaged. That's why the solenoid isn't permanently engaged like you think. Power is available to the relay coil, but only when the transistor gets the signal does the unit ground, thereby energizing the solenoid and engaging the overdrive. That's why it only engages when the transmission engages 3rd gear (didn't someone mention that earlier in this thread? I'm sure I saw it somewhere).

I was also hoping you'd notice the problem with the dashboard light and solenoid being in series as drawn. Think about it.

So now you're spinning this weird notion of me denying facts? I'm not the one insisting there is no overdrive in an AW71, that was you. And I'm not the one insisting that the overdrive is permanently energized. Hmm, unless you're claiming 1 2 and 3 are done with the overdrive engaged, and then it turns off. And I really hope you're not going to start insisting that grounds aren't necessary for electrical circuits because of the red lines in that drawing. And please don't say factory manuals are 100% perfectly correct at all times.

I've tried keeping it light and humerous. That's what the tongue in cheek aproach was for. For I could see by your writing style that you're not the type to handle corrections well. Lighten up my little pudgy kitten (intentionally humerous jab at ID). Life is too short to take yourself so self righteously. Live and learn a little. You're not as omnipotent as you think you are.

As they say back ole Meheco; amf.
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Old 06-24-2005, 04:15 PM   #24
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Well you are simply wrong, and it's still crystal clear that you do not know what you are talking about, have no direct experience with this circuit, and are unskilled at reading wiring diagrams.

I have used Volvo OD relays extensively for a wide variety of applications other than transmissions. The default mode (when power is applied to terminal #15 & ground to #31) of the automatic type OD relay is on, that is to say the coil is grounded via the internal logic circuit and the relay contacts are closed. The manual trans OD relay does exactly the opposite. But don't believe me, take an OD relay bench test it for yourself, something you have obviously never done. You can even see this clearly in the diagram above for when power is reaching the solenoid, it is also reaching both legs of the OD indicator lamp and is therefor not lit. If your theory was correct then power would not be reaching the solenoid, and not reaching both legs of the indicator lamp and the lamp would be lit (as it grounds out through the solenoid) whenever the solenoid was not powered, and as everyone who drives an automatic Volvo knows, the light is out at all times unless you manually turn it on (thereby deactivating the OD relay), the indicator lamp is not lit through the first 3 gears and the goes out in 4th. Unless you manually toggle off this relay via the momentary push button, it remains on at all times, it does not just turn off for 4th, it also does not just on for 4th, it is always on. If you will also note, there is no input to the relay that could tell it the trans was in 4th.

Quote:
Originally Posted by foxtrapper
I really thought that you'd traced the circuits yourself, thereby actually following them and thinking about them while you did it.
Been doing so all along, when are you going to start? You are defending a position that is indefensible in the face of the factory diagram I posted, anyone who can read a diagram will know this, and idiocy will not win out over facts. And as for tung and cheek, the tone of your response above was snotty, not humorous.

I'm not a baby sitter, I suggest you find someone else to wipe your nose for you.
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Old 06-24-2005, 05:17 PM   #25
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I think Foxtrapper needs to learn how to help without being a jerk; he came close but thought he was really smart and might as well take a shot at someone else who was trying to help. Three Fat Tigers is one of the most helpful maintenance and repair people here and is almost always right and would freely admit he was wrong if that was the case.

Foxtrapper may have read some books somewhere, but he has not studied the wiring diagrams or, if he has, he does not know how to read them. And he certainly has not been under the car with a test light. Give it a try. He does not even have to be able to read wiring diagrams to do that. I think he needs a large slice of humble pie.

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