Hello,

I have a 2007 Lexus IS350 with 72k miles. I changed the alternator yesterday after it failed, and now my car will not start. I have found several replies in various threads of others experiencing this same issue after changing their alternator, but have not been able to find any solutions. The dash lights up, but nav screen area does not. I can unlock the car with the key fob, but not unlock. Power seats, Nav screen area, etc do not work even though battery has been re-charged and is good. The car will not even attempt to turn over. I get a message on the dash that says "decompress brake before starting engine." Other than that no other messages. I attempted to read codes with a code-reader but I do not believe my car will switch itself into the "on" position so the OBDII reader cannot recognize my vehicle.

I have checked all fuses and power harnesses that were connect to new alternator to ensure they were put back on correctly. Has anybody else experienced this and have any solutions on how to fix it? Any ideas as to what would have happened by changing the alternator to cause these issues?

 

So you have power and the car wont turn over?
You sure your batt is good?
Check your batt connection! Make sure they are not corroded and on tight. My neg battery term.was not on tight enough and realized it when my car didnt start. I also replaced my alt and had no issues when I put it back.
I'd get a new connection from the alt and make sure it's connected properly.

 

Yes the battery is good. I had it checked and re-charged after the old alternator ran it down. I have also checked the connections on the battery as well as the connections onto the new alternator. They are all fine. It acts as if the car is in some sort of safe mode, where some items work and others do not. For example the car will unlock with the fob but not lock. The dash lights up just fine but not the nav screen etc. The only thing I can think to try at this point is re-connecting the old alternator and seeing if the car will then start to rule out a problem with the new alternator.

 

I would have your batt tested, they can tell you if a cell is bad. You could have bad cables too, it is a possibility.
You know that the batt starts the car ONLY, right? I'm not trying to be sarcastic but it seems pretty simple too me. Your stating the car wont even turn or start, correct? So there's no spark at all! That's a connection or batt problem. Maybe someone can explain it better or I'm not correct?

 

check break fuse and switch .

 

I have to ask...did you disconnect the battery during the ALT removal and install?

 

Were you able to figure it out I'm having the exact same problem?

 

I'm having the same problem with my is250. Anybody find a solution

 

U figure it out? I'm having same problem with mine as well. Been trying different fuses n relays but no luck

 

To the broken followers - Does the start stop button turn green when the brake is depressed?

If not, depress /push harder until it does.
And how are these fuses being verified? Most need to be physically extracted for visual verification. Others are breakers and should reset when cool but you need an ohm meter to test these.

There are several fuse panels A) by the battery, B) left fender under the cover, C) cockpit by OBDII port and likely others I am not aware of...

 

Light stays orange. Key fob is good battery is good. Dash and everything works just won't crank over. Brake is very stiff can't really push it down. dash says depress brake. So I can't depress my brake to start the car I tried pumping alot no luck. Not sure why changing my alternator would affect my brakes. Vacuum?

 

Over time the vacuum from the brake booster leaks out and/or several activations of the pedal use up the stored volume.

Reach under the dash and manually depress the switch(s) associated with the brake pedal or get both feet on that pedal and get it to move 3/4"... This MUST be ruled out as if it it just a matter of switch activation well there is nothing electrically wrong with the car.

Now you simply need a check valve or worst case is a new brake booster if it won't last for say 3 to 5 days.

 

Mine happen to be the fusible link. I got it started but it need s to be replaced trying to remove it now and find a replacement

 

the same happens to my is250. I forgot to disconnect the battery and I spark happened when I was trying to disconnect the battery. Can someone guide me what to check?.
The car lights are on but it wont crank the dashboard says depressed the brake pedal, the car sit power wont work