transmission diagnosis How is it done?

frangijon · October 28

Hello, I need your help. My 1995 Lexus S 400 does not have an Overdrive light on the gauges. I need to do a guide not for my transmission. Can someone explain to me how to do it correctly? I have performed the engine diagnosis with code 21 and 28, but I do not know how to perform the transmission diagnosis. Can someone help me? Thank you.

BigBoomer · October 28

http://www.lexls.com/tutorials/intro/codereading.html

It also gives you the Transmission codes (if any).
"For transmission codes, you count the blinks on the "O/D OFF" light. "

frangijon · October 28

Thanks BigBoomer

When I perform the dianosis the o/d off light does not light up or blink, that's why my question,

frangijon · October 28

I bought the car with a faulty gearbox and I can't move it. To get the fault codes for the transmission, do I plug in the cable, press this button and turn on the ignition?

Malc1 · October 28

To the top right hand( or maybe the left on your car ) side of the gear selector do you have the “ override” button to press that I have in my 95 car ?

that simply releases all the gears for me ……. I’ve only used it once tho

Malc

frangijon · October 28

Thanks for your help, do you mean the red arrow button below?

thanks

Malc1 · October 28

Yes that’s the one I pressed when one day my gears just seized …… first time ever …… I was in shock …….. instantly freed it all up and she then drove fine with normal gear use ……. about 3/4 years ago

Have you tried that ?

Malc

GMB · October 28

A good spray with WD40 might help?

VFR · October 28

46 minutes ago, GMB said:

A good spray with WD40 might help?

A good clean you mean (?) yes that thought crossed my mind as soon as I that mess.

Razor61 · October 29

17 hours ago, frangijon said:

When I perform the diagnosis the o/d off light does not light up or blink, that's why my question,

Hasta donde yo sé, su modelo LS400 Serie 2 o MK3 no tiene un botón de 'overdrive' y por lo tanto no tiene una luz de 'overdrive'.
Para los códigos de transmisión/caja de cambios necesitará Toyota Techstream o un equipo de diagnóstico compatible.

89-94 LS400

Malc1 · October 29

Paul or anyone ……. have you ever had to use that button I referred to ?

Malc

Razor61 · October 29

43 minutes ago, Malc1 said:

Paul or anyone ……. have you ever had to use that button I referred to ?

Malc

Do you mean the button in the picture, Shift Lock Override? If that's the button you mean, I do use it now and again on the drive to move the car back without starting the engine.

Razor61 · October 29

.

Malc1 · October 29

How’s it all going Francisco ?

Malc

frangijon · October 29

Thank you very much, my 1995 LS 400 does not have an overdrive button, so I understand why it did not have a light on the dashboard, now I understand why I cannot diagnose the transmission, so I can buy the Toyota Techstream software, but how does the car communicate with Toyota Techstream, the diagnostic plug is the old one

frangijon · October 29

16 hours ago, Malc1 said:

Sí, ese es el que presioné cuando un día mis cambios se trabaron... la primera vez... estaba en shock... al instante lo liberé todo y luego funcionó bien con el uso normal de los cambios... hace aproximadamente 3 o 4 años.

¿Has probado eso?

Malc

Hi, I'm working outside my house when I get home on Saturday I'll try, but I'm afraid that button is not the solution, when I can try it I'll let you know, thanks

Razor61 · October 29

1 hour ago, frangijon said:

but how does the car communicate with Toyota Techstream, the diagnostic plug is the old one

Eso será un problema, el sistema OBD1 y tal vez solo un concesionario Lexus/Toyota tenga el equipo correcto para comunicarse.

BigBoomer · October 29

Francisco, does the engine start and run? To be able to move the gear selector requires having the engine running.
The only way to move the selector with the engine not running is to press the ShiftLock Override which will allow you to put it in Neutral so you can push or tow the car.
The 95 is a Mk3 LS400 (95-97) so won't have the OverDrive button on the selector or the O/D Off indicator.

That is a TEC (ODB1) port (unique to Toyota) and getting a connector & code reader for those is very difficult.
Only a Lexus/Toyota dealer will be able to connect to that port as you need an ODB1 scanner as well as the adapter for that port. ☹️

frangijon · October 29

5 hours ago, Razor61 said:

Eso será un problema, el sistema OBD1 y tal vez solo un concesionario Lexus/Toyota tenga el equipo correcto para comunicarse.

The big problem is the automatic transmission failure. I can't go to the Toyota workshop for diagnosis.

frangijon · October 29

5 hours ago, BigBoomer said:

Francisco, ¿el motor arranca y funciona? Para poder mover el selector de marchas es necesario tener el motor en marcha.
La única forma de mover el selector con el motor apagado es pulsar el ShiftLock Override, que te permitirá ponerlo en punto muerto para poder empujar o remolcar el coche.
El 95 es un LS400 Mk3 (95-97), por lo que no tendrá el botón OverDrive en el selector ni el indicador O/D Off.

Ese es un puerto TEC (ODB1) (exclusivo de Toyota) y conseguir un conector y un lector de códigos para ellos es muy difícil.
Solo un concesionario Lexus/Toyota podrá conectarlo a ese puerto, ya que necesita un escáner ODB1 y el adaptador para ese puerto. ☹️

The Lexus starts perfectly, I have the results of the engine diagnosis, code 21 and code 28 lamba probes, the car only runs in reverse, forward, it does not run, you insert speed D (direct) the revs go up but it does not run

Maybe this interface is suitable for a modern diagnostic machine?connection to the engine and change to modern obd?

Malc1 · October 29

C’mon now, be adventurous, drive in reverse then to the Toyota Dealer for some analysis 🧐

Malc

2 hours ago, frangijon said:

The big problem is the automatic transmission failure. I can't go to the Toyota workshop for diagnosis.

Razor61 · October 30

9 hours ago, frangijon said:

The big problem is the automatic transmission failure. I can't go to the Toyota workshop for diagnosis.

I know there is, or was, a Toyota handheld scanner/code reader, maybe the Toyota/Lexus workshop still have one that will work and will let you use it?
I remember seeing one of these for sale a while ago, I’ll find more information about the scanner, part number etc., and post it here or message you.

Razor61 · October 30

Have a look at the link below, this is maybe what you need. It looks more of a 'monitoring' tool than a code reader but may read codes as well.
From what I can see. it is a module with Bluetooth, bare wires to wire into a diagnostics plug, TOYOBD1 software on a tablet to read the data from the car.

OBD1READ with Bare wires

BigBoomer · October 30

The above device may work (fingers crossed!!).

The problem with the adapters that you found Francisco is that the modern ODB2 readers do not know how to talk the Toyota specific version of ODB1, so whilst it may work for some codes, it will not work for others. They also will not give any more info than the flashing lights on the dashboard.

For the transmission problems, it sounds to me like it is either a problem with the shifter linkage, or more likely one of more of the transmission solenoids are broken.