1990 Toyota Pickup Not Shifting To 4th Gear On Freeway Right After Cold Starts
 

Hello everyone,

I have a great 1990 Toyota truck pickup (automatic transmission) that my grandfather gave me. It runs great, but I've always had a problem shifting into higher gears when approaching speeds in excess of 50+ MPH on the freeway right after a cold start.

When getting on the freeway, I notice the engine reving at really high RPMs at about 50 MPH. It almost feels if I continue accelerating past 50+ MPH the engine would blow up because it didn't sound right.

I started counting how many shifts happen between 0 MPH and 65 MPH, and I can count 1st -to> 2nd gear is OK, 2nd -to> 3rd gear OK, but I can't hear the truck shifting into into 4th gear.

I took the truck to a local transmission mechanic and he said it was a bad "kickdown cable". He showed me the part on my truck (pic below) and pulled the "rubber boot" off the mount and showed me RUST inside the cable.

https://lh3.googleusercontent.com/-O...2520Markup.png
https://lh5.googleusercontent.com/-_...0/IMAG0526.jpg


https://lh4.googleusercontent.com/-q...0/IMAG0524.jpg

https://lh4.googleusercontent.com/-D...0/IMAG0518.jpg


The mechanic shot some WD40 down the cable and pulled on the inner cable to loosen it up. It seems to help.

Whenever the truck doesn't shift into 4th gear, I always get off at the next freeway exit, squirt WD40 down the cable and pull on the wire to loosen it up. When I get back on the freeway, it usually shifts into 4th gear (with "a little care").

By "a little care" I mean, when I feel it is about time to shift into 4th gear, I slightly back off the gas petal, then tap the petal forward to accelerate again, and the truck will usually shift into 4th gear. This same procedure will not work without pre-lubricating the cable with WD40 from a cold start.

I have a few questions, and I thought I'd ask the experts here ...

• Would a rusty kickdown cable (throttle cable) be the primary cause of this issue?
• Where can I get a kickdown cable like this?
• How much would a kickdown cable cost (about $70)?
• How difficult is it to replace the kickdown cable? Given the Onsite Repair manual for 1993 (slightly newer than my 1990) here: http://www.ncttora.com/fsm/1993/auto...10onvehicl.pdf
• How much would a reasonable mechanic charge me to replace the kickdown cable?

Thank you for any help you can give me!

-Brian

My truck specifications are:

• Toyota 1990
• Extra Long XCAB Deluxe
• 4 Speed Automatic (Not absolutely sure - VIN decode describes 4 speed)

Truck Sticker Information:
https://lh4.googleusercontent.com/-Z...2520Public.jpg

https://lh3.googleusercontent.com/-D...2520Public.jpg

I think re-lubing the kick don cable is something you can do yourself, even if you have very limited machanial skills. I would suggest you completely remove the cable. Go to a bicycle shop and get some dry slide. It is a graphite lube. Hang the cable verticle on something, and squirt the dry slide down down in the cable, move it back and forth, squirt some more until the cable is completely lubed from one end to the other. You will most likely want to use some penetrating fluid first to brake up all the rust. Hope it helps.

let me ask....do you run a thermostat?

I too have the automatic and yes, it needs to be at operating temp before it does it's final shift. when I was monkeying around with my truck and ran it a few days without a thermostat, I could barely get above 50mph and would drive all the way to work (18 miles) without it ever getting into it's final gear. thermostat back in, runs fine.

They won't shift into overdrive until they are warmed up, so it might be normal.
Get a new mechanic. It's not shift down cable, it's a line pressure cable.
When you stop to lube it you're probably just letting it warm up enough to shift into overdrive.

I'd take it in to get the tranny flushed and put a new filter into it. Sounds more like a filter issue to me.

But that's me.

Bingo! Toyota engineers programed it to do that.

it definately doesn't sound like a filter issue... Its working perfectly fine... my 09 corolla does the same thing

My 99' 4runner does the same thing, competely normal... it has to warm up before it shifts.
Also, the torque converter doesn't lock up until it's warm either.

Normal. [/thread]

Now if it never shifts into or drops out of overdrive AFTER reaching operating temp, that is NOT normal and it could be a number of things. Thermostat, coolant temp sensor, throttle position sensor, and trans temp sensor can all cause it to intermittently kick in/out of overdrive after reaching operating temp. Ask me how I know.

The next time you go to drive it on a cold morning, let it run for a few minutes before leaving the driveway. If it shifts just fine, then there's your answer. Your mechanic sounds like the kind of guy who tries to get people with blinker fluid. My Durango does the same thing. And in Colorado I can drive for a while in the winter before it warms up enough to make its final shift.

this same thing use to drive me crazy till i changed the thermostat. I guess these toyotas need to warm up a bit till they can shift

I know this thread is old, but here's my two cents for those (such as myself) who might be reading this later.

I am experiencing the same problem in my 89 Pickup, Base Model, 2WD, 2.4 FI. In my case, I know that the kickdown cable is sticking, likely due to rust at the bottom end. The truck has been sitting in my driveway for 5 years without being driven, though started up every month or so and run up and down the driveway so as to prevent total deterioration.

I recently did a ton of work, and put it back on the road. I've been pouring oil down the cable, working it in, and pouring more oil. It appears that the bottom end of the cable connects to the top of the transmission and is hard to get to.

The cable is now sticking intermittently, and I'm hoping that with some time and engine heat, it will unstick. But when it's stuck, the shift points are very high, and the transmission won't go into overdrive at all as the transmission thinks I'm flooring it.

I don't know what such a cable DOES cost, but it SHOULD cost about $25. But unless it's broken, I'd recommend going with oil or some kind of lubricant. If you can scrub the end with steel wool, that would probably be a good thing too. Just try to keep steel wool particles out of the cable housing.

Sorry Murcielago, that's not your problem. The line pressure cable (attached to the throttle) determines how hard the transmission shifts, not where it shifts. http://www.autoshop101.com/forms/AT24.pdf The throttle position, to the extent it determines shift points, is determined by the TPS.

If your line pressure cable is crapped up, of course, you should replace it. About $80.

@SCOPE103

What do you mean by how "hard" the transmission shifts? A shift is merely a change of gear ratios, and is always the same (i.e. you are either in the lower or the higher gear; there's no in-between), though it can occur at different RPMs and travel speeds depending on conditions. One (of several) ways that the transmission determines conditions is the cable mentioned. If you floor it, that cable communicates that information to the transmission which then downshifts as long as that would not cause the engine RPMs to exceed the max. Conversely, when you take your foot off the gas, it upshifts based on the same logic. The cable thus helps to determine the shift point. If it's stuck in the full-throttle position, shift points will be higher than they would be otherwise.

And that's precisely what my own occasionally sticking (in full throttle position) cable is doing to the transmission.

Did you read the link to the Toyota publication?

Automatic transmissions aren't just manual transmissions with a robot working the clutch and shifter. They use multiple brake bands and clutches to actually change the gear ratios; the force with which they are applied determines how "hard" the shift is (also called 'shift-shock'). If you want to compare it to a manual transmission, think of how you work the clutch: at low rpm and speed you let it out gently, but at high rpm (if you shifted there, like you do with an automatic) you'd let it out faster.

In the long-ago days (before 1975 or so), non-electronic transmissions did use the throttle position to determine shift points (as well shift effort, through setting the line pressure). Not so in an electronic transmission; the TPS guides the ECM, which does the shifting through solenoids. The throttle cable has nothing to do with shift points.

@Scope103,

I'm sure that what you say is true for more modern transmissions. My own truck is an '89, and the initial question came from someone with a '90.

On my throttle body, there are TWO cables. One connects the butterfly valve to the gas pedal inside the cabin. The other one runs from the butterfly valve to the transmission. On my truck, it behaves as described above, e.g., when the cable to the transmission is stuck (which corresponds to the gas pedal "floored"), the shift points happen at higher RPMs, and the overdrive fails to engage. When the cable is working, the transmission shifts at lower RPMs, and the overdrive does kick in at higher speeds. (>~45 MPH).

Perhaps you are referring to later models with more sophisticated transmissions? If the transmission functioned solely based on the TPS, why have the cable that I described there at all? Would the transmission work fine if I were to disconnect that cable?

I'd be curious if you have a reason for the existence of that cable that doesn't require me to read 34 pages of a Toyota training manual. (And I'm not trying to be sarcastic, seriously.) Thanks.

I have replaced the thermostat twice and still having the same problem

Can you elaborate for me? I have this problem with a warm engine. All the gears shift smoothly though. So I don't think (hope) I don't have a transmission issue. I started driving it today with the overdrive button on the shifter pushed in and it seemed to help a bit, but I think it could still do better.

+1 exactly what I was thinking.