chuckross1957

Well it seems my overdrive has bit the dust permanently. I have lost it briefly in the past , it always came back. So I checked out the external electrical part of the system. It looks like I'm getting good voltage to the solenoid. I'm hearing and feeling the solenoid click. I was doing some research on the A43D transmission and it seems it is identical to AW70 transmission used on a lot of Volvos (except for the tailshaft/flange). It is funny, I've actually found more info about the overdrive on Volvo forums. There is a bypass plate for the solenoid that is sold for the Volvos, it keeps the transmission in overdrive full time. Also the Volvo solenoid works on Toyotas, except the plug is different. I was wondering If anyone has tried using the Volvo transmission on a Toyota, Apparently it isn't too difficult to swap the tailshaft parts. At this point, I'll probably order a bypass plate or a Volvo solenoid. http://www.turbobricks.com/forums/sh...d.php?t=291145

chuckross1957

I installed the Volvo bypass plate. Now my overdrive seems to be working ok. With the plate installed the transmission basically works like an ordinary 4 speed automatic.

vital22re

iTrader: (2)

These systems will keep overdrive off if it thinks the engine has not sufficiently warmed up. Stuck open thermostat will do it. As well as a bad temp switch.

4runnerx3

Have you unplugged the computer for the tranny and see if you have OD? OD is when both solenoids are off.

chuckross1957

I'm not an expert on transmissions, most of what I have learned is by doing research on the internet. I haven't even dropped the pan on my A43D. There seems to be some confusion about the A340E and the A43D. As you can see in this link even experts can become confused. http://www.justanswer.com/toyota/8c3...utomatic.html# From my research I have found the A340E is electronically controlled and the A43D is not. The exception is the A43D overdrive solenoid is electronically controlled. By installing the bypass plate, you eliminate the electronic control for the overdrive function. So if I understand the A43D correctly, there is only one solenoid and that is the overdrive solenoid. Some folks, like me, were having problems with the overdrive dropping out very intermittently at interstate speeds. I believe the bypass plate can eliminate the issue in most cases. I suspect the overdrive solenoid was the problem in my case and I could have replaced it. But, I have never found a situation where I needed to downshift out of overdrive. And, by installing the plate I hope to narrow down the source of a very intermittent problem. http://www.ipdusa.com/products/4793/...oid-bypass-kit Note the "Product Description".

4runnerx3

I missed the 43D. Did the vehicle ever run hot before? What is the vehicle?

chuckross1957

It is an 86 2wd. I've never ran it really hot...but I'm not the original owner. No problems with the overdrive using the bypass plate. I'm reluctant to say the dropping out of overdrive issue is definitely and completely resolved because it was such a rare, intermittent issue before. I'm running the 180 superstat again. Also, I'm using a mix of Dex 6 (1 Quart) and Dex 3. I'm wondering how this transmission would do running straight Dex 6.

nomad26

Thanks for posting this I didn't use the plate I made my old solenoid work by grinding a slot between the two holes and replaced it . Works great

chuckross1957

Great to hear you solved the problem, I haven't had any more overdrive issues with mine since I installed the plate. One thing I was thinking about are the newer synthetic transmission fluids...I suspected they might flow better at cold temperatures. Better flow at cold temperatures might reduce the need for the overdrive solenoid. I found an article about Mobil 1 synthetic transmission fluid. I might give it a try the next time I change the transmission fluid. https://bestsyntheticoilguide.com/sy...ission-fluids/

nomad26

I used royal purple that was about 50 k ago I was thinking of putting in a fresh filter and oil and maybe replace the other solenoids . Maybe I will check out Mobil. The royal purple is pretty Pricy. Thanks again

old87yota

This is what I am going to use for my next Automatic Transmission Fluid change: https://parts.toyota.com/p/Toyota-Au...0718ATF00.html

nomad26

I may use that as well . Its not cheap either .