Sensors to overdrive

[Freewheeling8]

Overdrive has been out, just rebuilt, engine light and Radiator light flicks on and off, very sparatic, OD worked for a while then yesterday, stopped again. did most of the checks on this forum already. disconnected the temp. switch as suggested, I was told that there are three sensors that also control the OD. Maybe a short or open circut? please advise, thanks, Ros

[joegri]

hi freewheelin i had an automatic years ago and my od wouldnt work when it got cold out. turned out there was a bad temp sensor that would,nt send the signal to shift into od. i dont remember which 1 it was ( i didnt do the repair) but all was good after that replacement. as far as the dash flickering i.d check the coolant resivoir and silly as it sounds go over the battery connections . just a though n hope it helps a lil bit good luck n post back what the fix is!!

[davidgracevan]

-hi sir freewheeling, mine is a 88 2WD A/T, i had this problem also before, and the problem was lose wiring connections in the terminals. check all wirings of the OD system, i believe that in 2WD A/T theres only one sensor that affects the OD system which was the Water Temperature Switch... i hope i helped you you a bit...goodluck... :)

[timsrv]

The OD (Over Drive) circuit on a 2wd van is incredibly simple and easy to troubleshoot. I realize you have already disconnected the water thermo switch but for the sake of anybody else chasing this problem I'm going to explain things in detail (so disregard the parts you have already checked). Here's a diagram showing the OD circuit on a 2wd van:
http://i8.photobucket.com/albums/a23/timsrv/TVT%20pics/Drive%20Train/2wdodcircuit.jpg

The water thermo switch is a likely problem. It's on the side of the engine next to the distributor.
http://i8.photobucket.com/albums/a23/timsrv/TVT%20pics/cooling%20system/CoolantTempSender-1.jpg

I'm not really sure why Toyota saw the need for this switch. It might be more relevant on the 4wd vans with the transmission ECU, but on the 2wd vans it's just a simple temp switch that limits OD operation. That switch's only job is to prevent OD operation below 131 deg F engine coolant temp. When your vehicle is warm, this switch should be "open" (no continuity). When your van is cold it should be "closed" (continuity). If you don't have an ohmmeter, just disconnect the sensor and the OD should work all the time (even when cold). If the problem doesn't change with this disconnected, then that sensor is probably okay and your problem is somewhere else.......maybe the relay or the solenoid. The relay is mounted under the front of your center console box between the shifter and the emergency brake. Be sure and check the wires there making sure none of them got disconnected, damaged or pinched. The solenoid (which hardly ever fails) is mounted on the side of the transmission.


For a location of these components and more troubleshooting info CLICK HERE (http://www.toyotavans.org/community/tips/manual/014_AUTOMATICTRANSMISSION.PDF) and scroll down to AT-14 to AT-18. Also, here's a link to another forum post regarding the OD system: http://www.toyotavantech.com/forum/showthread.php?330-Overdrive-issues. Tim

[timsrv]

Radiator light flicks on and off, very sparatic...........

As joegri already mentioned there is a float sensor in the bottom of your coolant overflow bottle. It's normal for the radiator light to flicker on/off when the level is low. Tim

[Freewheeling8]

Thanks a bunch everyone for the quick reply, I think with all the information you guys gave me I will solve this problem, especially the electric scematic, I can understand the system now, and can do some of the checks myself. Both mechanics I brought it to were baffled. thanks again!

[Freewheeling8]

HI again, It seems that i might have a short in the system, OD has not worked for the past few days, Really cold here. then this morning I drove from Santa fe to Albuquerque, about ten miles down the road the OD kicked in, worked for a while, then it dropped out once again, just as mysteriously as it kicked in?? My Radiator light and engine lights still flicker on and off. The enginee light comes on when accelerating. Radiator light, sometimes on sometimes off. I check the overflow resivour, it is full. Just might have to take it to a Auto electrician, Pretty pricey at $100 an hour. Any connections to a cheaper reliable mechanic in The SF or Abq. area would be appreciated. OK onward we go. thanks.

[theschnell]

Does your engine get up to temp? It has to warm up a little for the OD to kick in. If your thermostat is stuck wide open it might only get hot enough at certain times, which would explain it kicking in only occasionally. I had a 4runner that had to get fully to temp before it would shift. Changed the thermostat and it shifted every time. With these vans it doesn't have to get all the way to reg, temp but it does have to warm up some. I drive about a mile before mine shifts into OD and I'm in GA where its not that cold.

[Freewheeling8]

Hi thanks for the quick response. My van heats up fine, so I am sure the thermostat works, before the OD stopped working it did have to warm up first, as you mentioned. Still thinking there is a short in the system. OK thanks. Might just have to bite the bullet and have an electrician look at it.

[EZHIKER]

I have experienced those symptoms. Issue was resolved by replacing the rusted fusible link near the battery.

[Freewheeling8]

Still dealing with my overdrive going out. :dizzy:Took it once again to a recommended mechanic, he tested the elect. system, told me that my solenoid was bad, there was 5000 OHMS coming off my solenoid where there should be only about 13 OHMS, so trying to find a solenoid for my 1987 Van. Anyone out there have one sitting on a shelf, any suggestions? Thanks a bunch.

[EZHIKER]

https://www.discounttoyotaparts.net/toyotaoemparts.html
http://www.toyotapartszone.com/oem/toyota~solenoid~assy~transmission~85420-28020.html

[timsrv]

If the thermo switch is disconnected, yet it still requires extremely long warm-up times, then it's likely due to a failing/sticking OD solenoid. Considering these things hardly ever fail and considering the cost for new, I would get one from a salvage yard. I bet a Pick & Pull would sell for under $20. If you can't think of a situation where you'd ever want to turn it off, you could do what this guy did: http://www.hiacehobo.com/2012/08/toyota-hiace-overdrive-solenoid-bypass.html :rol:. Tim

PS: In case that link goes dead, here's a picture from his post:

http://i8.photobucket.com/albums/a23/timsrv/TVT%20pics/Drive%20Train/OD%20solenoid%20mod_zpsifrgyfk2.jpg

If you remove your old solenoid & grind/drill as required to make it look like the picture above, you will never have issues activating your OD again :wnk:. You will however have a problem if you ever need to turn it off :doh:. Tim

[RobJoe]

Overdrive stopped working the other day on my 85 van wagon 2wd automatic. After checking connections and fuses I dug in to the OD button on the console, Bad idea. I got in deeper than i should and broke the switch.:wall: with no switch, what is the default setting, OD on or off or screwed. If i could just bypass the switch and choose to always have OD I would. 4 wires red white blue and black. Once this is resolved I'll go thru finding out why OD stopped working, temp sensor or solenoid.

[timsrv]

The way these are set up the switch & the thermo switch actually need to be open for the OD to work. Barring any other faults, the OD will still work with the switch and the thermo switch removed from the circuit (connectors dangling). These two things only serve to inhibit the OD (prevent it from working). If circuit for either switch is closed, the OD will not work. If you wanted to electrically bypass everything (make it work no matter what) you could bypass by unplugging the blue relay, then jumping the red/blue wire in the connector to the black wire (paperclip or something metallic will work). This essentially bypasses everything and will send power to the OD solenoid any time the ignition switch is turned on. If you want to get fancy, you could wire a switch between these two terminals and turn it on/off that way (no pesky thermo switches or relays causing you trouble). In theory you could use the existing OD switch to jump these terminals, but I'm not sure what the rating is on that switch, but suspect it's low (was only designed to power the relay coil so may or may not hold up if used to power the solenoid coil). If jumping these terminals doesn't make it work, then it's either a problem with the harness (wire or connector), a problem with the power supply, or a bad OD solenoid. If you verify there's 12VDC at the solenoid, and it still doesn't work, then it's a bad solenoid.

BTW: If you jump the OD relay terminals permanently, just be aware there's 12vdc in this spot, so you'll need to protect it from shorting (put tape or something over any bare conductors). Tim

[Javier]

I just started experiencing this problem the overdrive is going out intermittently. I have a 1989 automatic 4wd is there anything different on the 4wd or is it just the solenoid, relay, and fusible link?

[timsrv]

Here's another thread with more information: https://www.toyotavantech.com/forum/showthread.php?330-Overdrive-issues

[Javier]

Does anyone know if the solenoid for a 2wd and 4wd are compatible or the same thing? I am looking at one on ebay right now since mine is non functional. I have a 1989 LE automatic 4x4Thanks!

[timsrv]

Does anyone know if the solenoid for a 2wd and 4wd are compatible or the same thing? I am looking at one on ebay right now since mine is non functional. I have a 1989 LE automatic 4x4Thanks!

If your solenoid is getting power and it's not shifting into OD, then (and only then) should it be replaced. And yes, these are the same on all van transmissions. Volvo also used this same solenoid with the only difference being the single wire terminal end (a review of this thread (https://www.toyotavantech.com/forum/showthread.php?330-Overdrive-issues) should give details and part numbers). Tim

[Javier]

If your solenoid is getting power and it's not shifting into OD, then (and only then) should it be replaced. And yes, these are the same on all van transmissions. Volvo also used this same solenoid with the only difference being the single wire terminal end (a review of this thread (https://www.toyotavantech.com/forum/showthread.php?330-Overdrive-issues) should give details and part numbers). Tim

Thanks for the support, I have checked all the possible causes and the solenoid is faulty.

[Javier]

I just replaced the od solenoid with a brand new one I ordered from Ebay $+180 delivered, works like a charm and shifts like a dream:clap::yellowvan:

[Diy2k]

Awesome Javi!


Not to break your heart but this is an option as well.

https://www.ebay.com/itm/New-A-T-Overdrive-Solenoid-W-O-Rings-for-VOLVO-240-242-244-245-OE-1239928/174128259649?fits=Make%3AVolvo&hash=item288ada6241:g:aFAAAOSw1V9ePQt4

[Javier]

Great!! I was told that wouldn't work ooh well it's good to know for future references better late than never

[timsrv]

Awesome Javi!


Not to break your heart but this is an option as well.

https://www.ebay.com/itm/New-A-T-Overdrive-Solenoid-W-O-Rings-for-VOLVO-240-242-244-245-OE-1239928/174128259649?fits=Make%3AVolvo&hash=item288ada6241:g:aFAAAOSw1V9ePQt4

FYI, I got that one and have put approx 80k miles on it. It has leaked from day 1. It doesn't leak a lot, just enough to make my van undercarriage a bit nasty from the mixture of dust and ATF. If I had to guess, I'd say it leaks about 1 cup every 5k miles. It has functioned well, but I despise leaks. if I had to do it again I'd probably just pay the $180 or whatever for a quality part. Tim

[Javier]

Update to now 7/13 /21 and my od solenoid is leaking the one I paid $180 for wow wtf. 🤬 I suppose I will try the volvo one. Seller will not claim warranty on part.

[MarkH]

To replace my non-functioning overdrive solenoid, I got one of those blanking plates off Amazon or Ebay that keeps the overdrive engaged all the time. It leaked when I first installed it. It turned out that the supplied o-ring was too thin and barely protruded above its groove. I replaced it with a thicker o-ring and it's been fine since.

[ssocal87]

Hi Tim - I'm trying to follow this, but for an 87 4WD. My OD takes a very long time to engage, about almost 6-8 miles in 80 degree temp, and I disconnected the water thermo switch to no avail. This started after I changed the thermostat to a lower temp (170 I believe). I read on your post to "jump" with relay wires, but not too sure and wanted to get more details on that. The 7.5 amp fuse is good, checked wiring; non damaged. As for why I changed the t-stat, I had issues with overheating, and on a hot day, it gets hot, but seems to not go over too much 1/2 way up now, so I hope I am good. Fan clutch is working well, radiator is good.

Overall- just can't seem to get past this OD issue. Thanks, Tim for all your help and prior.



The OD (Over Drive) circuit on a 2wd van is incredibly simple and easy to troubleshoot. I realize you have already disconnected the water thermo switch but for the sake of anybody else chasing this problem I'm going to explain things in detail (so disregard the parts you have already checked). Here's a diagram showing the OD circuit on a 2wd van:
http://i8.photobucket.com/albums/a23/timsrv/TVT%20pics/Drive%20Train/2wdodcircuit.jpg

The water thermo switch is a likely problem. It's on the side of the engine next to the distributor.
http://i8.photobucket.com/albums/a23/timsrv/TVT%20pics/cooling%20system/CoolantTempSender-1.jpg

I'm not really sure why Toyota saw the need for this switch. It might be more relevant on the 4wd vans with the transmission ECU, but on the 2wd vans it's just a simple temp switch that limits OD operation. That switch's only job is to prevent OD operation below 131 deg F engine coolant temp. When your vehicle is warm, this switch should be "open" (no continuity). When your van is cold it should be "closed" (continuity). If you don't have an ohmmeter, just disconnect the sensor and the OD should work all the time (even when cold). If the problem doesn't change with this disconnected, then that sensor is probably okay and your problem is somewhere else.......maybe the relay or the solenoid. The relay is mounted under the front of your center console box between the shifter and the emergency brake. Be sure and check the wires there making sure none of them got disconnected, damaged or pinched. The solenoid (which hardly ever fails) is mounted on the side of the transmission.


For a location of these components and more troubleshooting info CLICK HERE (http://www.toyotavans.org/community/tips/manual/014_AUTOMATICTRANSMISSION.PDF) and scroll down to AT-14 to AT-18. Also, here's a link to another forum post regarding the OD system: http://www.toyotavantech.com/forum/showthread.php?330-Overdrive-issues. Tim

[timsrv]

If it engages eventually and your water switch is disconnected, then it sounds like a failing (sticky) solenoid. If that's the case jumping the relay would not help. I had one that was doing that so I changed the transmission fluid. That helped, but the solenoid eventually got bad again. I then replaced the solenoid and that fixed it, but the transmission already had 270k miles on it and it failed shortly after.

If you never need to disable the OD and you want to bypass, the best way is to put one of those bypass devices in place of the solenoid. They are inexpensive and there are no moving parts to fail. Installation is easy, just 2 screws. Tim

[ssocal87]

Thanks, Tim. I'll try the tranny fluid change first, as I try to locate the part for the solenoid mod. I think I read it's a Volvo part?
I hope changing the T-Stat didn't cause any of this!

[timsrv]

https://www.ebay.com/itm/362007789161?fits=Make%3AVolvo&hash=item5449587e69:g:iRMAAOSwiONYM3Ab

Changing to a lower temp T-stat shouldn't have anything to do with your OD troubles, but based on past experience I would not recommend anything other than a genuine Toyota T-stat. I'm not sure what reason you'd have to go to a 170°, but keep in mind these engines were designed to run with a 180° T-stat. If you're having trouble overheating, going with a lower t-stat won't fix......it will only prolong the inevitable. If it's overheating you should figure out why and take care of the root cause. Tim

[ssocal87]

Hi Tim,

I finally got to putting a solenoid bypass. I drove it, but it still seemed to not make a difference, and did not go into overdrive. Is there something I’m missing to do? It’s a 4wd auto.

I did not cut off the solenoid wire or solenoid itself, I wrapped it up and zip tied it attached to the frame. Any thoughts?

thanks!



If it engages eventually and your water switch is disconnected, then it sounds like a failing (sticky) solenoid. If that's the case jumping the relay would not help. I had one that was doing that so I changed the transmission fluid. That helped, but the solenoid eventually got bad again. I then replaced the solenoid and that fixed it, but the transmission already had 270k miles on it and it failed shortly after.

If you never need to disable the OD and you want to bypass, the best way is to put one of those bypass devices in place of the solenoid. They are inexpensive and there are no moving parts to fail. Installation is easy, just 2 screws. Tim

[timsrv]

When you take off you should hear/feel when each shift point occurs. If you have an RPM gauge it's even easier to detect. Are you counting 3 gears or 4? If only 3, does the transmission ever shift down to a lower gear when you floor it? If the other shift points are late and it doesn't downshift, then perhaps it's a problem with the "kick-down cable"??? If your other shift points are normal and the kick-down works, then it's most likely an internal problem inside the transmission.

[ssocal87]

Thanks. Yes, it shifts and seems to be stuck in 3rd. When I floor it, it does kick down to a lower gear.
With the solenoid bypass does the temp have any bearing on the shifting?

[timsrv]

No. With the solenoid bypassed there is no electrical control for OD. It's a matter of hydraulic pressure and where it's allowed to flow. My guess it's a stuck valve in the valve body. Tim

[Elazzzer]

Hello everyone!

Long time reader, first time writer here. Im forever grateful to this forum for all the helpful information Ive been able to discover. Ive been having issues with the overdrive not engaging in my 86 2WD automatic. I disconnected the Water Thermo switch, I swapped out overdrive relays and checked the wiring, I flushed transmission fluid and I checked my fuses. I swapped out solenoid with one from the junkyard and I had overdrive for a bit after doing that but it went out again. I would have to press the OD button on and off when 4th gear was suppose to engage on the highway and that was working for a bit before going out. Anyways! Im at the point where Im going to get the overdrive solenoid cut like the bypass plates they sell on eBay and IPD. My question is, do I leave the cable plugged in after I attach the bypassed solenoid or do I cut the cable? Thanks in advance

[Elazzzer]

Well I ended up going at the overdrive solenoid with a Dremel and recreated Tims pic of the modified solenoid. Van has regained overdrive and it’s ready for the road again! Thank you Tim and the rest of the gang for showing me the way! So now do I reconnect the water Thermo switch or do I just leave it disconnected?

[timsrv]

Thank you for the feedback :). Plugged/unplugged doesn't matter now. OD will work regardless.....Tim