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OBD2 code U0129 - no communication?

Tiny
JHORDI
  • MEMBER
  • 2014 TOYOTA COROLLA
  • 2.4L
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 20,000 MILES
I accidentally touch the remote amp wire to ground on the amp and by doing that it shut off my radio and my auto windows do not operate. When I turn on the car it does not want to go into any gears, it just stays in parking.
Saturday, December 27th, 2014 AT 9:27 PM

36 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,892 POSTS
Hello,

Yes, it does sounds like you lost a fuse. here is a guide and the power distribution wiring diagrams to help you test the fuses and the fuse locations also there is an accessory relay I would check as well:

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

and

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Check out the diagrams (below)

Let us know what happens and please upload pictures or videos of the problem.

Cheers, Ken
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Monday, February 26th, 2018 AT 12:50 PM
Tiny
POWERMOTORSPORTS
  • MEMBER
  • 4 POSTS
  • 2004 TOYOTA COROLLA
Computer problem 4 cyl Front Wheel Drive Automatic

Car get flooded, change a new ECU, but OBD scanner cannot connect and get codes?
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Sunday, August 9th, 2020 AT 11:56 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,892 POSTS
There is an OBD fuse that I would check first, check out the wiring diagrams for the ALDL connector so you can see how the system works.

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

Check out the fuse panel and ALDL wiring diagrams (Below)

Let us know what happens and please upload pictures or videos of the problem.

Cheers, Ken
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Sunday, August 9th, 2020 AT 11:56 AM (Merged)
Tiny
POWERMOTORSPORTS
  • MEMBER
  • 4 POSTS
OBD fuse is OK, check the power of OBD port is also OK, since OBD is directly connected to ECU for memory, I wonder why it does not respond since it is already new ECU. Check the lline an everything is ok
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Sunday, August 9th, 2020 AT 11:56 AM (Merged)
Tiny
MMPRINCE4000
  • MECHANIC
  • 8,548 POSTS
If diagnostic port fuse is OK, then it could be a loose/kinked/pulled wire to link. Scanner should power up when connected to port regardless of position of ignition switch. Does the dash light up when the key is on?
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Sunday, August 9th, 2020 AT 11:56 AM (Merged)
Tiny
POWERMOTORSPORTS
  • MEMBER
  • 4 POSTS
OBD port has several pins that I checked, I only have some based on the service manual. Like Power, GND, Signal GND. All these are OK we have 12 volts supply and to the ignition switch but not coming out so I replaced the switch and the car came back to life thanks for your help I love this site.
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Sunday, August 9th, 2020 AT 11:56 AM (Merged)
Tiny
MMPRINCE4000
  • MECHANIC
  • 8,548 POSTS
Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help

Cheers
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Sunday, August 9th, 2020 AT 11:56 AM (Merged)
Tiny
NIXO22
  • MEMBER
  • 4 POSTS
Hello house, I just joined. I have the same ODB2 connection problem. I have a 2006 Toyota corolla and each time I tried connecting an ODB scanner to it, I always get an "error in connection". Where do I start from?
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Sunday, August 9th, 2020 AT 11:56 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,892 POSTS
Hello,

Have you looked a the OBD fuse? 7.5 amp.

Check out the diagrams and guide in my above post and get back to me.

Cheers, Ken
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Sunday, August 9th, 2020 AT 11:56 AM (Merged)
Tiny
NIXO22
  • MEMBER
  • 4 POSTS
Yes I did check the 7.5A fuse for OBD and the fuse was ok though I didn’t test with a test indicator to confirm. The metal strip in the fuse was still intact.
However the round illuminating light around the cigarette jack does not come on when I switch on my lights.
I have both the ABS and Brake check light on in the dash.
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Sunday, August 9th, 2020 AT 11:56 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,892 POSTS
There is a 30 amp fuse in the passengers fuse panel that powers all of the systems you have mentioned.

Use the post above to see how to find and test

Cheers, Ken
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Sunday, August 9th, 2020 AT 11:56 AM (Merged)
Tiny
NIXO22
  • MEMBER
  • 4 POSTS
Hi there, finally I was able to fix the Brake and ABS dash lights all by my self at $0 cost. I just checked the integrity of the connection from the 2 front ABS sensors to where they connect with the ABS unit. Both wires were sheared so I just did a thorough termination( had the two terminals of the battery taken out first before proceeding). Connected back the battery, started the car and BINGO all lights were off.

I think the very first things we should do when trying to troubleshoot such problems are to carry out visual inspections and look out for open lines.
Thanks for your wonderful suggestions.

Nixo.
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Sunday, August 9th, 2020 AT 11:56 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,892 POSTS
Nice work, we are here to help, please use 2CarPros anytime.

Cheers, Ken
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Sunday, August 9th, 2020 AT 11:56 AM (Merged)
Tiny
NIXO22
  • MEMBER
  • 4 POSTS
My OBD port is still a problem. Cannot communicate with an OBD II scanner.
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Sunday, August 9th, 2020 AT 11:56 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,892 POSTS
I know you said you checked the OBD fuse and it was good but does it have power?

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Please let us know what happens.

Cheers, Ken
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Sunday, August 9th, 2020 AT 11:56 AM (Merged)
Tiny
SCHO1RYAN
  • MEMBER
  • 5 POSTS
  • 2005 TOYOTA COROLLA
  • 1.8L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 200,000 MILES
Key on in ignition there is no check engine light coming on, fuel pump works, coils and injectors are getting power. With the no communication would this be an ECM problem?
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Friday, June 25th, 2021 AT 5:10 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,810 POSTS
Hi,

I'm not sure I understand what is happening. Is the problem that you cannot connect via the DLC? Is the vehicle running?

Let me know.
Joe
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Friday, June 25th, 2021 AT 5:10 PM (Merged)
Tiny
SCHO1RYAN
  • MEMBER
  • 5 POSTS
Correct the vehicle does not run. Originally I was chasing a fuel issue but when I went to check for any engine codes via obd2 port I was unable to connect (no communication). That’s when I noticed the check engine light never illuminates with the key in the on position. The problem is the vehicle doesn’t not run and I need to get it running.
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Friday, June 25th, 2021 AT 5:10 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,810 POSTS
Okay, lets start at the data link connector (DLC). If you look at pic 1 below, it shows the connector. Pin 5 (brown wire) goes to ground. Confirm there is continuity to ground via that pin. Also, check pin 4 for ground. Pin 4 is chassis ground and 5 is a signal ground.

Next, pin 16 is constant 12v. Check to make sure there is power. If there isn't, check the fuse identified in pic 2.

Let me know what you find.

Joe
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Friday, June 25th, 2021 AT 5:10 PM (Merged)
Tiny
SCHO1RYAN
  • MEMBER
  • 5 POSTS
Using a test light I confirmed pin 4 and 5 continuity to ground. Pin 16 also had constant 12v.
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Friday, June 25th, 2021 AT 5:10 PM (Merged)

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