Would replacing the computer also reset the immobilizer?

Tiny
DAWNHOOVER
  • MEMBER
  • 2000 LEXUS RX 300
  • 2WD
  • AUTOMATIC
  • 154,000 MILES
I'm pretty sure the immobilizer is activated in my car. Also, it was running weird before that. Shifting weird, bad gas mileage, idling high, not downshifting properly. So, I think the computer is bad. Would replacing the computer also reset the immobilizer? Keep in mind one day the car was running okay and the next after being parked the crazy Shifting issues started.
Monday, July 3rd, 2023 AT 3:10 PM

8 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 50,584 POSTS
The PCM and BCM work together with the immobilizer, I would run a CAN scan which is easy to do to see what codes come up before replacing anything. You can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

Here is how to replace the PCM and BCM in case you need it, you can get a preprogrammed unit by searching Google or Ebay. Check out the images (below). Please let us know how it goes
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Tuesday, July 4th, 2023 AT 10:52 AM
Tiny
DAWNHOOVER
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  • 30 POSTS
My friend has a scanner, and it always says different things when he plugs it in, and it keeps saying can't connect to ECU.
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Tuesday, July 4th, 2023 AT 9:10 PM
Tiny
KEN L
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Okay, let's check the OBD fuse 7.5 amp in the fuse panel inside the car. Here is a guide to help you check it for power when the key is on, also please plug the scanner into a different car to make sure it works.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Please let us know how it goes.
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Wednesday, July 5th, 2023 AT 12:23 PM
Tiny
DAWNHOOVER
  • MEMBER
  • 30 POSTS
The OBD is working and the scanner is also. I'm ordering a new ecu that will be programed to my VIN. Will that help with the immobilizer issue?
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Friday, July 7th, 2023 AT 12:01 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 50,584 POSTS
Yes, it should, the PCM and BCM work together with the immobilizer. Can I ask if you have checked the fuses? Please check them with the systems on.

This guide can help:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Please let me know what happens.
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Saturday, July 8th, 2023 AT 10:53 AM
Tiny
DAWNHOOVER
  • MEMBER
  • 30 POSTS
The fuses are good. We just started the car with the scanner plugged in and it stays running until we unplug it. Will a bad ECU do that? This is the scanner he has.
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Saturday, July 8th, 2023 AT 5:40 PM
Tiny
DAWNHOOVER
  • MEMBER
  • 30 POSTS
I found the problem, one of my ground wires was not bolted to anything. Hooked it up and she started right up, no more check engine light or trac off light. She runs like a new car. Should last me a while it's 23 years old but she's in great shape and only has 130,000 miles. Thank you so much for your help.
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Sunday, July 9th, 2023 AT 6:13 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Glad you could get it fixed, thanks for letting us know. Please use 2CarPros anytime we are here to help.
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Monday, July 10th, 2023 AT 9:56 AM

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