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Transmission?

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I own 1991 LS 400 (160k miles).

Three times this week I experienced that rpm went up to 3k when driving at only 20 or 30mgh.

It happened last week too while I was driving a freeway.

Scared to death, I went to a repair shop right after, and let them check.

They told me when they tested, it went fine.

But suggested to change transmission fluid, so I changed it.

However, since I had the same problem this week a couples of times,

I am considering to try a different repair shop.

Before I go, I'd like to pull the transmission diagnostic codes and see if that tells me anything first.

I checked the owner's manual and found it does not tell me anything how to pull the codes.

Do you guys know how to?

And, if I have to change the transmission, I found I can buy a rebuild one for $1300 with one year warranty, or $2000 with two year warranty, or a junk tranny from $400 to $1200. I bought this car one year ago for $3900. I am not sure it is worth to fix this by paying around $2000 (including labor).

I would like to hear you guy's opinion on this.

Thank you in advance.

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I own 1991 LS 400 (160k miles).

Three times this week I experienced that rpm went up to 3k when driving at only 20 or 30mgh.

It happened last week too while I was driving a freeway.

Scared to death, I went to a repair shop right after, and let them check.

They told me when they tested, it went fine.

But suggested to change transmission fluid, so I changed it.

However, since I had the same problem this week a couples of times,

I am considering to try a different repair shop.

Before I go, I'd like to pull the transmission diagnostic codes and see if that tells me anything first.

I checked the owner's manual and found it does not tell me anything how to pull the codes.

Do you guys know how to?

And, if I have to change the transmission, I found I can buy a rebuild one for $1300 with one year warranty, or $2000 with two year warranty, or a junk tranny from $400 to $1200. I bought this car one year ago for $3900. I am not sure it is worth to fix this by paying around $2000 (including labor).

I would like to hear you guy's opinion on this.

Thank you in advance.

Welcome to the LOC! :cheers:

Absolutely pull any DTC's before anything! Here's how:

http://www.lexls.com...odereading.html

Common prob is a shift solenoid gone. Also check that your fluid level is correct.

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I really doubt that your transmission needs replacing. Most likely an selonoid or something relitivly small. Once you pull the codes post them back up and let us know.

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Okay. I will try to pull the codes first. Thank you guys.

Welcome to the club, and follow their advice, they are two of the best,

fill out your profile so we can get to know you...

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You say the engine intermittantly revs up to around 3K RPM but I cannot understand why you think this is being caused by a faulty transmission unless the transmission is shifting into 1st suddenly and increasing the engine RPM but if this was the case you would also feel the engine breaking effect.

The only way to be sure is to wait until the fault shows up again then slip the shift in neutral when it happens and see if the RPM stays the same if it does it is the engine not the transmission causing the problem.

I certainly wouldn't consider throwing money in to a possible cause only to find you still have the same problem.

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I pulled the diagnostic code and it says, 25 and 28.

25 - Air-fuel ratio lean malfunction

28 - Main oxygen sensor signal (on right bank)

Is it possible that oxygen sensor problem can cause this symptom?

My O/D light was continuously blinking without ceasing.

Does this mean that my transmission is probably not a cause?

Thank you guys in advance!

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Although I have never had the O/D light blink, I experienced similar symptoms when one of the wires in the left trunk hinge was broken only the "R" light illuminated when the brake pedal was depressed. Also before the engine is up to temperature, you often see the same hanging RPM'sThe transmissions on these cars hardly ever fail so I doubt you have a major issue.

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Although I have never had the O/D light blink, I experienced similar symptoms when one of the wires in the left trunk hinge was broken only the "R" light illuminated when the brake pedal was depressed. Also before the engine is up to temperature, you often see the same hanging RPM'sThe transmissions on these cars hardly ever fail so I doubt you have a major issue.

When I press the break pedal, my "R" light is also on now. And "open trunk" signal is always on. But how is these "R" light and "open trunk" signal related to the symptoms I experienced?

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Although I have never had the O/D light blink, I experienced similar symptoms when one of the wires in the left trunk hinge was broken only the "R" light illuminated when the brake pedal was depressed. Also before the engine is up to temperature, you often see the same hanging RPM'sThe transmissions on these cars hardly ever fail so I doubt you have a major issue.

When I press the break pedal, my "R" light is also on now. And "open trunk" signal is always on. But how is these "R" light and "open trunk" signal related to the symptoms I experienced?

Always helps to list all of your symptoms in your initial post. Sounds now like the trunk harness indeed as VB has suggested. If you do a search you'll find many links for this prob. Here's one:

http://us.lexusownersclub.com/forums/index.php?showtopic=17013&hl=Trunk+hinge+wiring+harness

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Always helps to list all of your symptoms in your initial post. Sounds now like the trunk harness indeed as VB has suggested. If you do a search you'll find many links for this prob. Here's one:

http://us.lexusownersclub.com/forums/index.php?showtopic=17013&hl=Trunk+hinge+wiring+harness

It never came up to me that the R light, "open trunk" signal, and the transmission is all related. thank you guys. I will explore further. You guys are gre8!

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Yup, exactly your problem and luckily for yoy, an easy and free fix.Carefully pry the wire pack out of the left trunk hinge. It will take you awhile to unwrap all the tape but when you are done, you will see a broken white (I think) wire). I used 2 crimp style connectors and fused in a short piece of wire. Tape it back up and everything should be fine. The first time I did this, I pushed all the wires carefully back into the hinge but it continued to flex and broke again. Now I just leave the curved part of the wire pack loose.

As far as the clogged transmission filter, I doubt it. Try this fix first. Should take under an hour.

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The first time I did this, I pushed all the wires carefully back into the hinge but it continued to flex and broke again. Now I just leave the curved part of the wire pack loose.

Yeah leave it loose and give it some extra length. Two more things that I'm not sure are covered in other threads or not. If you leave that section loose, make sure when you're loading up the trunk that nothing snags those wires while travelling or when removing your load. The other is to inspect all the other wires and do a pre-emptive repair for the rest to allow for more flex. That bundle is so tight that inevitably another might break. I did the whole batch and have never had a prob since.

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exactly. When the wire(s) break, it causes all kinds of shifting problems. Problems which have sent many a Lexus owner to their friendly local dealer who proceeds to bend them over sharply. Easy fix on your own, expensive fix at the dealer.

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