VOLVO A40D having issues with the gear shift

[alexbridge]

The truck makes perfectly fine the changes to 1-2, 2-3 but the problem comes changing 3rd to 4th it comes back to 2. We don´t have any power problems, the truck starts and run, the only issue is when it gear shift change 3 to 4. We hired the Volvo technics and they have been checking any leaks, changed oil and filters, they told us that the problem was with the computer and we changed it but it remain the same. The last thing they told us was that the problem was with the brake pump, so we will change it to see if this is the real issue. Any of you guys have knows what we can do to fix the issue?

 

[funwithfuel]

So, are you able to observe any stored errors in the display? When it fails to upshift, do you get a red central warning on the dash? Is there any indicator for "door open" or "bed up" shown on the display. These are software limitations that should keep you in second or third.
If you don't see any warnings, then we better check pressures. It's a bit difficult to rig the hoses and gauges up into the cab with you. We are concerned with clutch K1 and brake B1. You will see in the attachments where the ports are located, and what pressure you should expect to see.

 

[funwithfuel]

Here's the rest. Hope this helps. Now if you go into 4th but the apply pressures are significantly low, you could have a failed brake apply seal. If you see no blip in pressures, then the solenoid might be faulty.

 

[alexbridge]

The transmission and the pressures are within the ranges. The internal coils of the clutches are working well and were tested with the scanner. What does not have pressure is the brake pump and it shows a red light when speeding up in the shape of a triangle and it does not advance and the parking sensor also appears because it has the connected sensor that goes behind the cabin, which is the one for the service brakes that not even the markers on the dashboard indicate pressure

 

[alexbridge]

We changed the brake pump and the red light and the parking light doesn´t appears anymore. But the problem with gear shift change 3 to 4 keep happening. Anyone knows what else can it be?

 

[funwithfuel]

You still have no 3-4 shift. But, you no longer have the central warning and red triangle?

 

[alexbridge]

That´s correct still no have 3-4 **** and don´t longer have the central warning and red triangle since we changed the brake pump

 

[funwithfuel]

Then follow through with pressure test against K1 & B1. If you have apply pressure but no gear, then you have a mechanical failure , internal. If you're lacking the brake apply, look at the corresponding solenoid.

 

[alexbridge]

Now the shift goes from 2C to 3L and goes back, yesterday it goes to 2C-2L-3C and goes back to 2C.

 

[funwithfuel]

So it's recognizing 3C is not applying and kicking back to 2. So instead of focusing on 4th, we should be looking at 3rd.

 

[alexbridge]

What do you recommend to do?

 

[funwithfuel]

Measure brake B3. It's obvious you have K1 because it moves. B3 gives you 3rd. Make sure your apply pressure comes up, if not, look at solenoid for B3

 

[funwithfuel]

See previously attached pdf to find corresponding test port

 

[alexbridge]

We already checked the solenoids and there´s no failure. What else can it be?

 

[funwithfuel]

If you have clutch apply pressures where they're supposed to be at the range shown, then you have a mechanical problem. It's imperative to verify the solenoid are delivering fluid upon command. Again, no need to waste time with K1 Focus on B3.
Have You sampled the oil off the drain?

 

[alexbridge]

We've changed the transmission oil and filters, when we drain the oil there were no signs of transmission wear, so we think that the problem isn't on the transmission, i think is electric but we don't know where.

 

[alexbridge]

New update, there's no pressure on B2-B3. We don't longer have failure on brake sensor, box sensor, engine slope direction sensor and terrain slope regulation sensor. It could be the seals that go on the brake pistons of the transmission that the pressure is leaking there, but they have to check K1 and B1,B2,B3 with another pressure gauge. Does the pressure has to be checked with the computer or with the manometer?
If we don't have pressure on B2-B3, why the truck is going foward? When it is going foward appears on the screen found arrows. I will post a video of how the wheel is turning it gets in the 3C but it comes back to 2C, Can it be a problem with H and L?

 

[alexbridge]

volvo a40d - Google Drive

drive.google.com

this is the video and picture of the tests they are making

 

[funwithfuel]

You haven't even come close to low/hi shift. The lack of B3 says either the solenoid is plugged, stuck or simply malfunctioning or, the brake is broken. If the brake can't apply, you lose forward momentum. The fact your moving forward at all says K1 is ok. You're just lacking a brake. Whether electric or hydraulic remains to be determined. I seem to remember 2 to 3 shift failure to be quite common, not as common as a grenaded dropbox, but close.

 

[alexbridge]

So what we should do next?