Transmission shifting up and down

[ondra]

I have recently noticed, that at certain situations the transmission is hesitant and shifts up and down.

This happened twice on the way between Vancouver and Whistler: going around 80kph, light on gas pedal, light uphill, almost no load in the car (just me and some gear), shifted up and down around 4 times in 2 seconds (the slower gear was around 2200-2500 rpm, the higher at 2000 rpm). Couple more times it did only one cycle (shifts up and then as it realized there is not enough power shifts back down immediately).

And then I've noticed couple of times that I lightly depress the gas pedal and it immediately shifts down but I'd still thing the current gear was more than sufficient.

The car (1997, diesel, swb, low roof) has 52K, transmission fluid changed at 45K when I bought the car, inspected the fluid and looks completely clear. No other transmission issues noticed. I'm inclined to think that it's because I'm too light on gas pedal - hard to press it harder on the winding sea to sky hwy), but any thoughts appreciated!

Thanks a lot!

[thelazygreenfox]

What transmission fluid did you use? Do a search on fluids from my posts. lots of info.
TLWF

[ondra]

Not sure, transmission was flushed by Mardy. Any suggestions?

[ondra]

So I measured the level of the ATF after a 10 minute warmup, 10 minute drive and 5 minute idle (engine was at working temp halfway the drive, outside temp around 12C). Looks I might be running short on ATF? Or is this ok for such a short drive?

[ondra]

And this after another 20 minute drive.

IMG_20150501_162824~2.jpg

[ondra]

Sorry, tapatalk didn't add the picture, so here it goes. ATF levels look good to me. Talked to a local shop in Whistler and they suggested something around the gas pedal sensor - that it's giving the transmission wrong information about the load, gas pedal position etc.

[thelazygreenfox]

change trans fluid. Use diaqueen from can tire.

[ondra]

So I drove back to North Van from Whistler, keeping my eye on everything I could. Weird stuff happening almost immediately on the hwy (just a couple minutes of driving). Going slightly downhill at 80kph with light foot on gas (almost engine braking) and it changed to 3rd gear (2500rpm), accelerating went up to 3000 rpm and then finally changed up a gear. Gears very unstable when trying to maintain stable 60-100kph, 4th gear usually engaged usually way too early (around 60kph)

Just out of curiosity I tried to diagnose the throttle position sensor (TPS) - I have a couple OBD readers and some software, but they all failed to connect (will try further to find a working combination of reader/sw). So today I borrowed a voltmeter from my roommate and plugged it into the TPS directly (the far end of the cable going from TPS). Reference voltage 4.95V, adjustment value 0.85V, going up to 4.05V with pressing the gas pedal (went smoothly up). So I went for a drive - after yesterday I expected to see the signs rather sooner than later, but even a 30 minute drive didn't show a single weird behavior. Round the block, hwy, climbs, I tried everything I remembered having trouble with gears, now running as I would expect. Measured the TPS again - 0.85V to 4.05V going smoothly.

Maybe a loose cable that got set in place when plugging the voltmeter, haha, unlikely. But I guess I'll wait until it starts happening again.

change trans fluid. Use diaqueen from can tire.

Keeping this in mind. Is next on my list. Thanks!

[stever1000]

Did you find the problem?

[ondra]

Shifting good this weekend... Confused!

[ondra]

You know what? I just took it for a quick steep climb on Mountain Highway in North Van (engine was warm) and I noticed something. Going around 45-50 kph, 2300 rpm... Hard to explain, it was barely noticeable, but there were some slight quick dips in rpms (not more than 50 rpm for a split of a second), not accompanied with shifting, loss of power or anything else. If there's a lock up clutch in the torque converter, might that be it? Apart from that I kept my eye on the shifting the whole weekend and didn't notice anything like before. What do you think? Thanks for your time and effort!

[timgilbertson]

Mine does the exact same thing, so I'm interested if you find a solution. I was considering just changing the fluid to see if that helps.

[Big-Bird]

Did you happen to read this Tranny File on the forum?

http://www.delica.ca/manuals/L-400%20Ma ... otrans.pdf

It should offer some insight.

[ondra]

So a little update here. Still not fixed, working my way through it.

Brought it to Butch @ CVI. He adjusted TPS and things got better... for a bit. After driving a bit more it was back. Looks like it happens after an hour of driving or more. Sometimes when I press the gas pedal after coasting (flat or slightly downhill) it shifts into 4th (2000 RPM) and immediately shifts down to 3rd (2500 RPM) - but there was no lack of power. Sometimes when going uphill it tries to shift to 4th (or lock the clutch) but fails and returns to 3rd.

Butch advised me that another point of failure could be the temp sensors. "The two sensors are located on the left side of the engine. Big white sensors."

So I identified them as these...



Unfortunately the plug connectors are blocked/isolated from the other side, so I can't connect multimeter.



I unplugged both of them and tried to measure the plugs. The front one is completely silent, the rear one reads 10 V in one of the holes. I tried to measure the resistance of the sensor, but I failed, there's too little room around to connect everything properly.

1) Is 10V correct? I thought cars use either 5V or 12V.
2) Is there any reason the front plug has no power on purpose?
3) Is there any way of unscrewing the sensors without emptying the cooling system or without a major leak of coolant?

[Big-Bird]

According to the application charts the 1994-1996 L400 uses Tranny Model # V4AW3-7 (plus some 2 or 3 letter ID Tag) in both the V6 (gasser) and 4M40 (Turbo Diesel) models.

This tranmission has an oil temp sensor on the side of the valve body housing. If it misbehaves it can put your tranny into a false SAFE MODE and will change how the tranny shifts. This operates an indicator light on the dash when the heat gets too high. It may not light when the sensor isn't reading properly.

There are a few solenoids on the side of the valve body (sorry bud these are inside the transission oil pan area).

Delica Solenoid.JPG (42.65 KiB) Viewed 5185 times

There are some differences in gear ratios and speedo gear ratios but thats not important here.
If you wanna know the ID tags: (UI/UJ/UIL/UJL/LI/MG/MGL/ML) and each one is slightly different internally

The 10V you read is probably due to the way its wired through the tranny control box inside the dash. FYI the tranny control box located on the floor behind the plastic divider at your feet.

The control box is probably getting 12volts at the input side and then it sends a lower voltage to the sensor. I find using paper clips useful in the hard to reach areas such as the temp sensors. The paperclip wire can be inserted inbetween the silicone seal and the plastic jacketed wire. Just ensure the paperclip tips are only long enough to give you a multimeter contact point. If you give the wire too much of a 'tail' they might touch/ground and roast a circuit in the tranny brain.

If I had the wiring schematics I could probably tell you what the ohm readings are supposed to be but I can't find the file....used to have the master electrical manual all in PDF. Lost the stupid memory stick!

Have you checked your overdrive switch on the end of the shifter arm? They do have a common internal break point but when they break it usually prevents OD from activiating without holding the switch down. Does your work properly?