OBD-2 port not powered; is there a blown fuse?
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VStar650CL
- Technical Expert
- Posts: 8391
- Joined: Thu Nov 12, 2020 1:25 pm
- Car: 2013 Nissan Altima 2.5 SL
2004 Nissan Altima 2.5 S
Re: OBD-2 port not powered; is there a blown fuse?
Could be the same thing, or it could be an ECM with a bad CAN driver or other CAN issue. If the car is a no-start, check the ECM relay. You might want to try a high-end scanner that can detect the tranny, ABS, BCM, IPDM, and other systems that should be present. If you get nothing, then some device is killing the whole bus and not just the ECM. On Nissans with the TCM inside the tranny, the TCM's are notorious for crashing the whole bus when they malfunction.
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raven69david
- Posts: 74
- Joined: Sat Feb 29, 2020 9:28 pm
- Car: 2002 Infiniti Q45
Re: OBD-2 port not powered; is there a blown fuse?
The car starts but idles rough. If you press the gas pedal, it shuts off. I’m trying to get someone with a good scanner to try and connect to the car but haven’t been able to get anyone to come to my house to scan it.VStar650CL wrote: ↑Sat Jan 01, 2022 11:14 pmCould be the same thing, or it could be an ECM with a bad CAN driver or other CAN issue. If the car is a no-start, check the ECM relay. You might want to try a high-end scanner that can detect the tranny, ABS, BCM, IPDM, and other systems that should be present. If you get nothing, then some device is killing the whole bus and not just the ECM. On Nissans with the TCM inside the tranny, the TCM's are notorious for crashing the whole bus when they malfunction.
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VStar650CL
- Technical Expert
- Posts: 8391
- Joined: Thu Nov 12, 2020 1:25 pm
- Car: 2013 Nissan Altima 2.5 SL
2004 Nissan Altima 2.5 S
Re: OBD-2 port not powered; is there a blown fuse?
If it starts and runs at all then the ECM is alive, so you need to find out why it won't talk. The first thing to check is fuses and power to the DLC port.
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raven69david
- Posts: 74
- Joined: Sat Feb 29, 2020 9:28 pm
- Car: 2002 Infiniti Q45
Re: OBD-2 port not powered; is there a blown fuse?
The DLC has power as it powers the Carly unit. I checked the pins and even removed it to make sure it was making a good connection and it was fine. The pins aren’t bent and I’ve checked all the fuses to make sure they’re not blown in the main fuse box and IPDM.VStar650CL wrote: ↑Sun Jan 02, 2022 8:17 amIf it starts and runs at all then the ECM is alive, so you need to find out why it won't talk. The first thing to check is fuses and power to the DLC port.
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VStar650CL
- Technical Expert
- Posts: 8391
- Joined: Thu Nov 12, 2020 1:25 pm
- Car: 2013 Nissan Altima 2.5 SL
2004 Nissan Altima 2.5 S
Re: OBD-2 port not powered; is there a blown fuse?
Most scanners need both ignition and B+ on the DLC. If they only have B+ they'll wake up but won't read anything. Check ignition power at the DLC before assuming the "wake up" means anything.
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raven69david
- Posts: 74
- Joined: Sat Feb 29, 2020 9:28 pm
- Car: 2002 Infiniti Q45
Re: OBD-2 port not powered; is there a blown fuse?
Thank you for all your help and suggestions. You’re awesome.VStar650CL wrote: ↑Sun Jan 02, 2022 9:58 amMost scanners need both ignition and B+ on the DLC. If they only have B+ they'll wake up but won't read anything. Check ignition power at the DLC before assuming the "wake up" means anything.
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