Where is the cam sensor on a 1991 lexus ls400. It was rinning fine then when i changed the battery it only starts when he wants to.

You change no parts

The only parts that get replaced, are
those that fail a test

Have a repair shop take over & find a problem
thru proper testing vs: a wish & hope strategy
on a guess, by replacing good parts

NO JUST FILL GEARBOX LEVEL AND CHECK AGAIN AFTER RUNNING ENGINE

Time for a rebuild

You never change fluid in a trans that
already slips,it will get worse,you done

Its a hot start issue.

Can be related to low fuel pressure or problem with crank sensor.

Also it can be weak battery or starter.

But possibilities are to be inspected to confirm what exactly it is.------

To troubleshoot and confirm the issue,i suggest you refer few solved help links with similar types of problem like yours:------

Click the link below:------

1991 Toyota Trecel: Engine Starts fine but dies when gets Warm?

http://whatisbyme.blogspot.in/2012/05/1991-toyota-trecel-engine-starts-fine.html

-------------

1994 Toyota Pickup: Starts fine but dies in few seconds?

http://howtobyme.blogspot.in/2012/05/1994-toyota-pickup-starts-fine-but-dies.html

------------

1995 Lexus LS400: Running Hot?

http://whatisbyme.blogspot.in/2012/05/1995-lexus-ls400-running-hot.html

------------

2002 Toyota Camry: Puff of Blue or White Smoke while Starting?

http://whatisbyme.blogspot.in/2012/05/2002-toyota-camry-puff-of-blue-or-white.html

------------

Multiple problems on car: Car runs hot, A/C blows hot and car starts surging?

http://schematicsdiagram.blogspot.in/2012/04/multiple-problems-on-car-car-runs-hotac.html

--------------

Delay starting on Toyota Prius?

http://schematicsdiagram.blogspot.in/2012/02/delay-starting-on-toyota-prius.html

-----------

Honda car will not start intermittently?

http://technoanswers.blogspot.in/2012/02/honda-car-will-not-start-intermittently.html

--------------

Vehicle Starts, Runs and Loses Power

http://whoisbyme.blogspot.in/2012/07/vehicle-startsruns-and-loses-power.html

--------------

Intermittent starting issues on Volvo 760?

http://schematicsdiagram.blogspot.in/2012/02/intermittent-starting-issues-on-volvo.html

-----------

Car starts and cuts off immediately?

http://repairhelpcenter.blogspot.com/2012/01/car-starts-and-cuts-off-immediately.html

-----------

Car won't start when cold?

http://schematicsdiagram.blogspot.com/2011/12/car-wont-start-when-cold.html

===========

These details will help.

Thanks.

Its a hot start issue.

Can be related to low fuel pressure or problem with crank sensor.

Also it can be weak battery or starter.

But possibilities are to be inspected to confirm what exactly it is.------

To troubleshoot and confirm the issue,i suggest you refer few solved help links with similar types of problem like yours:------

Click the link below:------

1991 Toyota Trecel: Engine Starts fine but dies when gets Warm?

http://whatisbyme.blogspot.in/2012/05/1991-toyota-trecel-engine-starts-fine.html

-------------

1994 Toyota Pickup: Starts fine but dies in few seconds?

http://howtobyme.blogspot.in/2012/05/1994-toyota-pickup-starts-fine-but-dies.html

------------

1995 Lexus LS400: Running Hot?

http://whatisbyme.blogspot.in/2012/05/1995-lexus-ls400-running-hot.html

------------

2002 Toyota Camry: Puff of Blue or White Smoke while Starting?

http://whatisbyme.blogspot.in/2012/05/2002-toyota-camry-puff-of-blue-or-white.html

------------

Multiple problems on car: Car runs hot, A/C blows hot and car starts surging?

http://schematicsdiagram.blogspot.in/2012/04/multiple-problems-on-car-car-runs-hotac.html

--------------

Delay starting on Toyota Prius?

http://schematicsdiagram.blogspot.in/2012/02/delay-starting-on-toyota-prius.html

-----------

Honda car will not start intermittently?

http://technoanswers.blogspot.in/2012/02/honda-car-will-not-start-intermittently.html

--------------

Vehicle Starts, Runs and Loses Power

http://whoisbyme.blogspot.in/2012/07/vehicle-startsruns-and-loses-power.html

--------------

Intermittent starting issues on Volvo 760?

http://schematicsdiagram.blogspot.in/2012/02/intermittent-starting-issues-on-volvo.html

-----------

Car starts and cuts off immediately?

http://repairhelpcenter.blogspot.com/2012/01/car-starts-and-cuts-off-immediately.html

-----------

Car won't start when cold?

http://schematicsdiagram.blogspot.com/2011/12/car-wont-start-when-cold.html

===========

These details will help.

Thanks.

It can be the issue with weak battery or faulty battery or if battery is ok,then its faulty starter causing the issue.
From start to end troubleshooting these problem i suggest you to click the link below and follow its procedure:-----

What to Do When Car Turns Over But Won't Start?
http://technoanswers.blogspot.com/2012/11/what-to-do-when-car-turns-over-but-wont.html


-----------
Car starting issues?

http://technoanswers.blogspot.in/2012/02/car-starting-issues.html
------------
Car Starting Problemshttp://whoisbyme.blogspot.in/2012/06/car-starting-problems.html

--------

1991 Toyota Trecel: Engine Starts fine but dies when gets Warm?http://whatisbyme.blogspot.in/2012/05/1991-toyota-trecel-engine-starts-fine.html
----------
1994 Toyota Pickup: Starts fine but dies in few seconds?http://howtobyme.blogspot.in/2012/05/1994-toyota-pickup-starts-fine-but-dies.html

---------
1999 Chrysler Cirrus: 8 IGN Fuel Starter Fuse Blows?http://whatisbyme.blogspot.in/2012/06/1999-chrysler-cirrus-8-ign-fuel-starter.html

-----------
2001 Toyota Camry: No start After replacing Battery?http://whatisbyme.blogspot.in/2012/05/2001-toyota-camry-no-start-after.html
----------
1989 Toyota Pickup Truck: Turns over but not start?http://whatisbyme.blogspot.in/2012/05/1989-toyota-pickup-truck-turns-over-but.html--------------
Car dead and will not Start?http://whatisbyme.blogspot.in/2012/05/car-dead-and-will-not-start.html
--------1995 Lexus LS400: Running Hot?http://whatisbyme.blogspot.in/2012/05/1995-lexus-ls400-running-hot.html

----------
2001 Toyota Prius will not start?http://whatisbyme.blogspot.in/2012/05/2001-toyota-prius-will-not-start.html
---------1996 Jeep Grand Cherokee: Engine will not start?http://repairhelpcenter.blogspot.in/2012/06/1996-jeep-grand-cherokee-engine-will.html-------------Mitsubishi will not starthttp://www.howtorepairguide.com
---------
These will help.
Thanks.

Either the temperature sensor on the radiator, or the relay is bad.
Pull a wire off the temperature sensor on the radiator.
If it stops the fans, then the sensor is bad and the relay ok.

check/change the crank sensor and check your ignition module

Clean, inspect and, or, Replace your crank sensor or, crank sensor wiring A loose crank sensor bracket or, a start relay has caused this before

cable and battery needs to be replaced you lost your ground and battery shorted out this will fix ut problem