cynsueell

2004 Lexus 430 is jerking (thunking) on front driver side just before coming to a complete stop. Brakes have been checked by about 6 mechanics and no one can find anything wrong. Lexus mechanic had me replace timing chain (car has 119,000 miles). He also replaced the motor mounts and replaced one sensor and cleaned others . Have now spent thousands of dollars and car still jerking. Nothing showing up on diagnostics. Any ideas on what if causing this? Appreciate any suggestions

mmarshall

Welcome to CL.

If it is a shuddering type of jerk just before a stop, it might be the automatic transmission's torque-converter lock-up mechanism (which is only supposed to work in the higher gears, as the car is moving) unlocking too late and allowing the car to slow down too much before it de-couples.

We also have a forum, BTW, for service-questions on this specific generation of LS....and a general maintenance forum.

https://www.clublexus.com/forums/ls-...2001-2006-158/

https://www.clublexus.com/forums/maintenance-11/

Tom57

I see it's a 2004, the year of the LS transmission recall. Check with your dealer to verify that the TSB for the car has been performed.

Johnhav430

Lexus replaced the timing belt, right?

Any effect from new motor mounts? What is this jerk like, I mean on the car, not the Lexus tech?

Is it there when you roll up to a stop in neutral?

rkw77080

Also try going in reverse to see if the same symptom occurs. This sounds like a brake problem, but can also be a transmission or suspension problem.

tallcaguy

Did the problem start suddenly or get progressively worse? It's interesting that you say it's just one side.

Agree w/ rkw that it sounds like brakes but those have been checked. Just visual? Have the pads been removed or replaced? If just one side, maybe a tie rod end? Thunk is the word I'd use for bad LCA's but you'd hear it over bumps, turning, etc.

I have an 04. Before the TSB, the 1-2 downshift (and upshift) at low speed was abrupt but felt it in the whole car (not just one side).

Sorry to hear it's cost so much money!

Tom57

This is why he should verify whether the TSB on the '04 trans has been done -- at least 'check the box' and eliminate it from consideration. The '04 pre-TSB was known to have hard downshift symptoms.

tallcaguy

Good point. I commented because the hard shifts at low speed affected my whole car. The OP describes the problem as coming specifically from the front drivers side. You're right about checking off all the boxes. It's a good approach.

rkw77080

Here's the TSB everyone is talking about... It's hard to imagine that the Lexus mechanics did not check this TSB prior to recommending the replacement of timing chain (typo?), motor mounts, and sensors.

Tom57

Yes, it would be amazing if the Lexus tech didn't check the '04 for the trans TSB ... but it's a really old TSB now, and as we've come to know rkw, strange things do happen! Look at Blue103's "discovery" that an '04 for sale is due for a transmission replacement (post 6) > https://www.clublexus.com/forums/ls-...-04-ls430.html

JffGRY706

so by looking at the TSB, if it had been done there would be a sticker affixed under the hood of my car. I just checked and there is no sticker in the place indicated so I am guessing it has not been done. my car seems okay to me except when in bumper to bumper slow moving traffic. vin # JTHBN36F750177304 man. date Aug 2004. also when I had my timing belt replaced the dealer did not put a sticker on for that either. would the TSB show up on the MYLEXUS site had it been done? thanks Tom and Rick, you should both be promoted to moderator status in my opinion

Johnhav430

Do dealerships put the sticker on when timing belts are done (indies do)? If that is part of the procedure, and they did not, it would make me wonder if they actually did the work. I think we have proven that dealer services do appear on Lexus Drivers, and anything added or edited do not, except for the login that put the entry in.

The sticker imho serves a purpose. Imagine if the factory forgot to put the warning 25,000 volts sticker next to HID headlamps.

Tom57

Suggest that you call your Lexus dealer and ask for the service manager. Provide your VIN and ask if the vehicle history reflects the '04 transmission TSB being performed. Also, given the date of manufacture of your LS, it may be after the date range for the trans TSB.

L dealers have their own timing belt stickers (different than the one provided in the Aisin timing belt / water pump kit). It seems some (lazy) Lexus techs fail to affix the sticker. Attached are samples of Lexus dealer installed timing belt stickers and their prominent location.

**Thanks for your vote of confidence. Pleased to help.

tallcaguy

Thanks to Tom and Rick. Your help is much appreciated.