check engine light

[MARSHALL WISE]

I recently purchased a 98 ls400 with 65,000 miles.  After about a week the check engine light came on. I took it to JM Lexus and they told me I needed to rebuild my transmission and replace the ECM,costing $4,000 +.  A week later, the check engine light disappears.  Shifts smooth as silk-problem solved!  Then the light reappears a week later and the shifting is a bit rougher.  I took it to an independent transmission shop and said to ignore the check engine light because the light comes on and off for no apparent reason.

Has anyone else have the same issues? If so, what do u recommend.

Edited October 4, 2019 by MARSHALL WISE
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[vissine]

What was the code of the engine light? Rebuilding transmission at 65,000 miles is none sense.

[MARSHALL WISE]

I will send you the codes in about a week. Thanks, M

[sha4000]

If it's the speed sensor that's a known issue that Lexus put a TSB out for years ago. I was able to get a new ECU for free in 2014.

[MARSHALL WISE]

Here is the code: P0763 electric shift solenoid. Mechanic told me that older, low mileage cars fluids begins to dry and become sticky due to lack of driving. 

Mechanic also does not recommend a tranny flush. Could cause more problems.  Question, would replacing the filter help, drain 1/2 the tranny fluid and replace with a transmission additive. Or just leave well enough alone.

Your Thoughts

[vissine]

If you have option to use gasket for transmission pan, by all mean, use it. I personally hate the RTV.

[sha4000]

On 10/18/2019 at 5:47 PM, MARSHALL WISE said:

Here is the code: P0763 electric shift solenoid. Mechanic told me that older, low mileage cars fluids begins to dry and become sticky due to lack of driving. 

Mechanic also does not recommend a tranny flush. Could cause more problems.  Question, would replacing the filter help, drain 1/2 the tranny fluid and replace with a transmission additive. Or just leave well enough alone.

Your Thoughts

If you are going to change the fluid and filter I would just change that filter so you don't have to pay to remove the transmission pan twice if the code is still there. Check out this thread it's a GS but uses the same tranny. Also i'm attaching some files to guide you if you want to change the solenoid.

https://www.clublexus.com/forums/gs-2nd-gen-1998-2005/399802-p0763-shift-solenoid-fixed.htmlat-8.pdf

[vissine]

If the code goes away after changing fluid, then it is dirty fluid and you need to change it for a few times when the code comes back.