Selespeed problems won’t select 4th

[Jimmybob78]

Hi,
Wondering if someone can help me out with a selespeed problem.
It has decided it won't engage 4 th gear anymore, both on city and manual mode.
It had a new accumulator about 2 years ago (maybe 2000km ago).
Symptoms are a bit weird once I started looking into it.
I have noticed now I only get 2 changes before pump kicks in suggesting accumulator problem, but it doesn't have any other accumulator symptoms.
When I try to run the end of line calibration it gets either about a third or sometimes about halfway when it gives error plausibility repot engaging reverse gear. At the same time logs error for low pressure.
The pressure monitor shows pressure drop lowest 34.9
Pump sounds normal, have swapped relay with fan one. Have checked oil level and for leaks, have removed and cleaned all elect connections.
I tried another diagnostic called low speed and also high speed solinouid and low makes a noise but high does not.
I feel like it's an electrical wire or plug gremlin but would be good to narrow down which, or maybe someone has solved this issue before.
Also no error light illuminated on dash.

[Jimmybob78]

Watching the pressure as it does the calibration, the pressure slowly drops as it's changing gears etc until it drops below 35, then it stops and tries error. The pump does not kick in until it's below 35 causing calibration to stop... weird.

[bazzbazz]

1/ Two gear changes before pump primes is normal for an accumulator that is 2 years old

2/ The usual causes for your trouble with the car not going into 4th are -
    A/ Loose "Pinch Bolt" - Re-torque "Pinch Bolt" to 30nm
    B/ Worn Engagement or Selection Sensor - I would replace both at the same time

3/ As for your System running out of pressure during calibration it is usually caused by the pump being tired. Though the pump may run
    fine and bring the system up to pressure under normal operation, when it is put under constant operational load during calibration it
    simply can't keep up fast enough.
    It can also be caused by a faulty pressure sensor, but as it seems to be reading the pressure ok, I would consider replacing the pump
    with a new unit first. You could also remove the Pressure Sensor and give a good cleaning.

I would like to point out that as I am not there to physically diagnose the car myself the issues could be caused by a myriad of other possibilities, this is all just educated deduction & reasoning.

[Jimmybob78]

1/ Two gear changes before pump primes is normal for an accumulator that is 2 years old

2/ The usual causes for your trouble with the car not going into 4th are -
    A/ Loose "Pinch Bolt" - Re-torque "Pinch Bolt" to 30nm
    B/ Worn Engagement or Selection Sensor - I would replace both at the same time

3/ As for your System running out of pressure during calibration it is usually caused by the pump being tired. Though the pump may run
    fine and bring the system up to pressure under normal operation, when it is put under constant operational load during calibration it
    simply can't keep up fast enough.
    It can also be caused by a faulty pressure sensor, but as it seems to be reading the pressure ok, I would consider replacing the pump
    with a new unit first. You could also remove the Pressure Sensor and give a good cleaning.

I would like to point out that as I am not there to physically diagnose the car myself the issues could be caused by a myriad of other possibilities, this is all just educated deduction & reasoning.

Thanks for your reply! The pump seems to keep up with the calibtation fine. But there are times the calibration allows the pump to get the pressure up to max and the pump cuts out. The trouble I have is that the pump won't start until after the pressure drops below 35, and causing an error.
I will clean the pressure sensor for sure. Then replace sensors as you said. These seem to be 2 seperate issues .

[Mick A]

I've seen a few gearboxes over the years break a tooth on the pinion and this ends up stuck in the end casing and stops the selector shaft from getting full travel so it cannot select 4th gear.

It's a very easy job to remove the end casing and see if the piece of metal is there. Only an idea not saying this is the problem but you seem to know a bit about selespeeds so you shouldn't have a any drama checking this if need be.

Cheers.

Mick.

[bazzbazz]

Always worth checking, while he's there he can re-torque the pinch bolt. 

These seem to be 2 seperate issues .

Agreed