Harsh Gear Engagement

[ambermarine]

Hi fellow Lexuns

I have just sorted out a problem that may occur in the future to all of you ,so I will pass on the info .

Earlier this year I started to experience a thud at the moment drive was engaged both in forward and reverse and there was more torque than usual when engaged as if the revs were twice as high as tickover.The mystifying part of this scenario was that there was no problem when the transmission was cold.I studied the forums both here and in the USA and all trails LED to the no 4 Solenoid (Shift Smoother) being at fault.What further complicated the diagnosis was the codes for a fault on the solenoid only show if it as failed and not if it is sticking.

I had determined this was the fault and had sourced a Solenoid at £180 but not purchased and arranged a lift so we could get under the car and replace it.

I then took another look at Club lexus at a topic showing how to adjust the harshness /softness of gear changes.

This is pictorial and involved adjusting the cable linkage from the gearbox that is connected to the accelerator, cruise control and throttle on the top of the engine under the black plastic plate next to the Throttle body.

When I removed the plate after warming up the transmission I immediatly noticed the cable that controls the valve in the gearbox was stuck in the out position.

This would increase the flow of fluid through the accumulater valve resulting in the thud I had been experiencing .I pushed the cable back in to its normal position and the thud disappeared.The cause of the cable sticking was dried out cable inner and sheath a quick burst of silicone spray and problem was solved.

As a general rule there would be no need to remove this plate and after 22 years the factory lubrication had dried out and there is oxidisation of the alloy bracket taking place which produces dust that had collected on the cable inner.

It is the removal of two 10mm captive bolts and one black non captive domed fastener on the plate to check this potential problem that could save you a lot of time and money.

[mikeyv]

I was only saying to my brother in law yesterday how smooth and almost imperceptible the gearchanges are on the LS, especially compared to an old Marina we had both driven years ago.

I imagine that even the slightest fault would be immediately noticeable.

Thanks for the tip, hopefully I'll never need it.

[ROYT]

Good info, great potential money saver1

[abs66]

Excellent tip thankyou.

Do you happen to have a link to the pictorial you mentioned please.

Cheers

Pete

[ambermarine]

Excellent tip thankyou.

Do you happen to have a link to the pictorial you mentioned please.

Cheers

Pete

Yes, but I cannot get it to paste so the only way on to the topic. Goto clublexus.com LS400 forum, type in the search box,

" softer gear changes" ,this will bring up a discussion on the subject but on the 2nd page , revert to page one and the topic starts at the top.

These damn computers what would we do without them.

[steve2006]

Excellent diagnosis and thank you for sharing it.

The correct cable adjustment is critical as you say in ensuring a smooth gear change and at the correct time.

I managed to misadjust mine after a starter motor rebuild but in my case it caused the transmission to shift up through the gears very quickly so at around 20 MPH it was hitting 4th ( overdrive) infact it was so fast you could count from 1 to 4 and feel the changes that quickly. Correct adjustment immediately sorted the problem.

[abs66]

Thanks for the directions, I will bookmark it when I find it.