Hey guys, I'm not new to Club Lexus (I lurk for help) but I am new to posting. I have a problem with my 2006 IS250 AWD. I have a compustar remote start system.

Let me give you guys a little information before I tell yall what's wrong. I walked out to my car after work and my keyless entry worked perfectly, I opened the door and sat down. That's when I push my brake pedal down and push the start button - no response. I automatically assumed it was a dead battery and popped my trunk open for my jump pack, that did not work either. I went ahead and cleaned the ground coming from the negative terminal to the body, now it would only crank but not start. This is when I replaced the battery with a new one from Autozone, now it was unresponsive. I had it towed home.

At home:
- Checked all fuses
- Cleaned all ground points
- Replaced alternator
- Verified fusible link was intact
- Replaced batteries on both fobs
- Replaced power supply module x5
- Replaced engine control module (switching back and forth)
- Cleaned up around terminals
- Made sure I was getting 12 volts from battery to fusible link

Previously, the push button start text was illuminated but is now no longer ( and neither the amber or green light on). The security light is not blinking and the wheel is not locked. Currently, the only thing that works is the interior and exterior lights (including brake lights), locking/unlocking from inside the car, moonlight open message, door open light, fuel door, power seats, and horn. OBDII port has power but can't read because I can't get it into acc mode. I think it has to do with the key system, it's acting like there's no key detected without the "no key detected" message. It's also not telling me to push the brake pedal down at all, but I'm ruling out a bad brake switch because my brake lights work. There's a good amount of owners on here who have dealt with the same issue but with no reply/answer, I'm hoping to change that.



A quick mention. At home, after replacing the power supply module I had the same crank no start condition, but after replacing the alternator I had no response anymore. When using remote start through my phone, it tells me tach sensing error.

Please yall just tryna get to school!

 

Throughout all of this, what is the PN of the power supply module replaced 5x?
What method was used to verify fuse health and why was the ECM replaced? Once the ecm was removed there is a pairing process needed to reunite ecm to immobilizer and if not done, i think it lands you here.
Look here or on youtube for ecm replacement hand-shaking. It's a 30 min process and you'll need a battery charger and a paper clip.

 

Hi there! I've seen you on every post here regarding this issue and I wanted to say thank you!

I verified fuse health with a multimeter and visual inspection.

The part number of the power supply module is 89670-53010. I replaced this part because some guy on the Prius forum had the exact same issues/symptoms as me, replacing this part fixed it for him. Sorry to clear things up, the power supply module wasn't replaced 5 times. But it was replaced 4 times, with an extra one sitting in a box. The first time I replaced it the car came to life immediately, crank but no start. Changed the alternator and hooked the battery back up, back to nothing. Anything after that I had no response.

The last thing that I've tried doing is replacing the ECM. I read on another post that a guy had solved his issue by replacing that part. I thought why not and replaced it anyway. I did try handshaking with a paperclip but had no success, I'll try again later today. I did it without having the battery charger attached, is having a battery charger attached during this process critical?

 

Yes, with the key on, battery voltage drops below threshold (11.75?) and it fails. Likely to reduce field theft if you don't have means to keep battery alive.

How is it so many things are being changed? Was the battery polarity reversed at any time?

 

It sounds like I've been doing the handshake incorrectly then, I've been doing it with the ignition off. Looks like my past efforts were a waste of time, but I can't get into accessory mode anyway.

I changed the alternator because I felt like it was on its way out. Battery polarity was never reversed, if so I think my fusible link would've popped first.

An update though, I got my push to start button text illuminated again (no amber or green though). Looks like I blew that fuse when probing with my multimeter. Double-checked all other fuses, all fuses are good once again. I am getting power to all four fuse boxes as well.

 

For fuse testing, grab a 12vDC incandescent test lamp. It places a mild load on the circuit and you probe both sides (well until 100% certain which bus rail is powered) then you do one side. Suspect there are others or some pin in a connector is not seated/conducting. Meaning, double check everything you've done.

Do an advanced search for
#2IS Electrical Troubleshooting

You should find other posts of mine with a node layout of what is powered and where it is.... When you see downstream items not powered, go upstream to the source. Hopefully you find the fuse or bum connector.