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  #11  
Old 03-07-2013, 01:00 PM
RedArrow RedArrow is offline
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Vehicle: 1986 Volvo 745 TD
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Default M46 overdrive issues ... 4th gear contact switch

Can someone confirm please if this is the correct od switch for my 1985 d24t.
Thanks. The 1985 d24 is not listed in the vehicle fitment guide but I guess all m46 trannies used the same switch. Thanks.
http://www.ipdusa.com/products/7426/...contact-switch
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  #12  
Old 03-10-2013, 11:36 PM
RedArrow RedArrow is offline
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Default M46 overdrive bad wires / under shifter boot!

After I resoldered my OD relay a few days ago, I decided to check on the passenger side seat heater switch as well. I took it apart and found out that it was completely oxidized to the point that the movement of the small parts inside was impossible. The small lightbulb that`s inside is burnt out and melted but somehow the seatheater works now. Anyways, as I was messing around at the handbrake/seatheater /shifter area removing all those plastic parts and switches, I inspected the OD`s wires that come from underneath the relays/fusebox , through the rubber shifter boot and up all the way to the 5th gear button on top of the shifter. I noticed that the connection near the fusebox was loose and both wires were so much hardened that I couldn`t even bend them. They cracked when I touched it (inside the rubber boot). Days ago I was about to order a 4th gear switch and a relay as well from ipd but today my od problem seems to be solved finally! I removed the aged heat shrink cover with the old plugs along with the cracked-burned wires. I used new wires and plugs to make sure they will not ground anywhere again causing me fake tranny problems. : ) Lesson learned. If you have m46 od issues, peel the shifter completely of all parts and inspect ALL wiring before you start worrying condemning your OD. I tested the od and it worked fine! ((At least I checked the fluid levels and learned a lot again about the M46 manual transmission (4-speed + Laycock de Normanville overdrive))). The green dash light came up happily so I finished the job with installing all dash covers and parts of shifter back. What a pain to get all that wiring into the tight shifter! I realized only later that the shifter knob was pushed down too much so it wasn`t easy to put the car into reverse. I also got surprised how much of greasy dust had accumulated on the shifter at the base where it moves down there… I had to remove lots of dust/hair/sand mixed with old grease to free the junction for some fresh synthetic ball-bearing grease. Oh, what a difference it makes! Now the shifter moves freely, goes into 1st and 2nd much lighter and reverse is easier too. Proper lubrication and the freedom of moving for all the shifter`s parts. I would love to get a new spring for the shifter btw (for the reverse) so it would be more comfortable to not to have to push that black thing down after getting out of reverse. All Volvos I drove had that thing `jump` down immediately but mine doesn`t. They even have that typical click sound to it. I also could not figure out how to get to that spring for removal but that`s not a big thing now. I will also buy a new 5th gear button so the `5` will be visible on the shifter. That would help me out explaining the tranny for curious observers and unbelieving passengers. Thank you for your attention and all previous suggestions on fixing my m46 od issue!Image03052013183248.jpg

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Last edited by RedArrow; 03-11-2013 at 12:30 AM. Reason: Grammar
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  #13  
Old 03-11-2013, 11:38 PM
Boots Boots is offline
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Default

Glad you got your OD problem sorted out...

For reference, there is a complete wiring diagram for the overdrive circuit, including the relay internals and pinout here: http://forums.turbobricks.com/showthread.php?t=202693.

I'm certainly going to save the drawings at the end of the post for any future diagnosing I may have to do...

Boots.
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  #14  
Old 03-13-2013, 09:12 PM
RedArrow RedArrow is offline
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Default overdrive wiring

Wow, that`s really a great source! I saved them for later! Now I just have to learn how to use them Isn`t it easier to understand Egyptian hieroglyphs in Gizah (at night)? That last wiring diagram drawing scares me more than a triple flat tire at 90mph.

Last edited by RedArrow; 03-13-2013 at 09:16 PM.
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  #15  
Old 03-13-2013, 10:10 PM
Boots Boots is offline
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It's just what you get used to I suppose. (I'm an electronics engineer by trade so I have to read schematics like these all the time!) The last diagram is actually of the circuit internal to the relay itself and is a very belt and braces design to ensure that the OD doesn't drop in or out due to electrical noise from the car's other equipment. In a 'cleaner' electrical environment, you could do the same job with about 5 components rather than the 20 odd shown there.

What's nice about the earlier diagrams is that they show ALL of the connections, their locations on the vehicle and which legs of the circuit carry current under which conditions - very handy...

Summary of the relay operation is as follows - for anyone needing to test one:

Pin 15 - +12v from ignition switch via fuse.

Pin 31 - Permanent circuit ground. (Chassis).

Pin 85 - 4th gear switch connection (enable). Relay will only engage if this pin is connected to chassis(grounded). (If relay is engaged and this pin is disconnected from chassis, relay will disengage.)

Pin 86 - Trigger input. Applying 12v to this pin momentarily (normally done using the pushbutton switch on the gear lever) will engage or disengage the relay sequentially for each application of the 12v signal. (If pin 85 is grounded.)

Pin 87 - Output of relay. Supplies 12v when relay is engaged. In normal use, supplies the current to light the bulb in the '5' light on dash and to engage the solenoid on the OD.

Interestingly, all of this is only needed to allow the use of a push-button rather than an on-off type switch to select or de-select overdrive.

If a slide switch or similar were used, none of the fancy circuitry, or even a relay would be necessary! It would just supply current to the lamp and OD solenoid in the 'on' position and not when 'off'.

Boots.

Last edited by Boots; 03-13-2013 at 10:12 PM.
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  #16  
Old 05-02-2013, 09:42 AM
ngoma ngoma is offline
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Quote:
Originally Posted by RedArrow View Post
After I resoldered my OD relay a few days ago...Attachment 51
I had to do this also.

Symptom: Could not engage OD. No response from pressing OD button driving in 4th gear.

Removed switch button, cleaned contacts, continuity testing showed better switch operation but still no OD. BTW, can test circuitry (engine off) via key in run position (disconnect GP relay ground terminal wire to avoid burning out the GPs), gear selector in 4th. Pressing the OD button should light the green indicator in the instrument panel, and should provide audible solenoid click.

Could get intermittent OD operation by pushing or squeezing the red OD relay on the relay/fuse panel.

Removing the cover of the OD relay (the hardest part of this process), and inspecting with a high-power loupe showed that ALL the soldered connections at circuit board-to-base were suspect. Minute cracking. I could get one to test intermittent continuity when flexing the two pieces.

This is the area on the other side shown in Redarrow's photo, sorry, I didn't get any photos of this.

Resoldered these joints with a 40-watt soldering pencil w/ sharp fine tip, and fine (.032" dia.) solder. Regular soldering gun and normal dia. solder would have been impossible here.

Driveway test showed consistent OD operation. Test drive today.
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  #17  
Old 05-02-2013, 06:18 PM
RedArrow RedArrow is offline
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Default OD disengages itself while driving

Issues with the m46, I believe, became known as `typical Volvo problems` that are very familiar among all those who ever had one. Interesting that my OD started living its own life again, also making decisions by itself... Issue: When I drive through rough surfaces that shake the car, or, when I hit a pothole/larger bump; then the 5th gear disengages by itself and I have to press the button on shifter to get back to normal (5th)... And it always takes it nicely and smooth & goes back to 5th the way it should. This frustrating action of jumping-out-of-5th thing *never* happens on flat roads. Can this be related to a worn transmission mount at all? I know that my tranny mount has been replaced not too long ago by someone very reliable. So now I`m wondering what causes this uncomfortable `in-and-out` thing.
(Btw, I want to mention here that it does not put itself *back* to 5th... only simply gets out of 5th by itself, at those mentioned circumstances).
Is there an easy way to remove 4th gear switch from transmission for inspection when the car is lifted? (As far as I remember there`s no great access to that without removing the tranny but I might be wrong about that.) I actually hate this thing to happen at or above 60mph.
Oh please, also, write suggestions on what`s the proper (highly suggested) type of tranny fluid to be used in the manual m46 transmissions. Thx!

Last edited by RedArrow; 05-02-2013 at 06:34 PM.
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  #18  
Old 05-02-2013, 09:48 PM
ngoma ngoma is offline
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Test for 4th gear switch is to hold shift lever hard down and to the right. That is supposed to make better switch contact. If that doesn't help on a bumpy road, than I would look again at the OD relay. I had to use a loupe and strong light on mine to see the cold solder joints at the junction of circuit board to base. Only then was it very obvious. Textbook cold solder joints. I had similar problem where if I could get OD it would switch itself off, often over bumps.

Type F ATF recommended for M46. There is a filter(s?) in there to clean.
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Last edited by ngoma; 05-02-2013 at 09:53 PM.
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  #19  
Old 05-05-2013, 06:01 PM
chad1966 chad1966 is offline
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Default Got my trans back!!

I just got my trans back this afternoon. Should be good to go for another few hundred thousand miles. I also modified the shifter for a little shorter throw and installed a stud so that I can put a threaded shift knob on. I will be moving my O/D button to an open spot on the dash.

Here is the link below. I cannot figure out how to imbed the picture.
https://www.dropbox.com/s/3vdc4r3eom...2018.26.29.jpg

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  #20  
Old 05-05-2013, 06:34 PM
RedArrow RedArrow is offline
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Default Small spring on m46 shifter

That transmission looks nice&fresh. How much is a complete overhaul?
BTW Did you think about having the original `5` built into your dash? (next to the rear demist switch maybe if there`s room still)

Also, another thing... last time I took mine apart I was wondering how to remove/replace that spring on the shifter that`s serving the black ring`s vertical movement for position `Reverse` of the shifter. It was too late+dark to figure it out. Anyone did that spring replacement? I could not find a place to order the spring from either.

It`s good to know that www.ipdusa.com sells great m46 parts and service kits if anyone interested.
http://www.ipdusa.com/newsletters/10...ter-components
Attached Images
File Type: jpg 5th gear.jpg (21.2 KB, 5 views)

Last edited by RedArrow; 05-05-2013 at 06:45 PM.
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