V1 OBD2 Fun Time

[PHENDERSON]

I finally have a running engine after 3 years. Well it barely idles. It has stage 2 cams and a bunch of other stuff. I have HP Tuners but unfortunately im getting no data from my obd2 port so it cant be tuned. The display cluster turns on but the tach and other meters dont work. Everything else electrical works.

Checked fuses and didn't see any blown. Are there any under the passenger foot rest?

Checked the obd2 with a volt meter and im getting nothing for voltage or resistance between any pins car on or off.

Any ideas where to start next? Im not good at reading wiring diagrams.

Hypothetically, could you just run wires directly from specific pins to the obd port temporarily to tune the vehicle?

Thanks,
Paul

 

[Gtstorey]

The running bad could be a result of the high speed data network not communicating correctly so you need to fix it right instead of trying to shortcut things.

Here is a troubleshooting guide fire the network

https://resources.aeswave.com/ATG-05_Network-Diagnostics-and-Module-Programming.pdf#:~:text=High%20speed%20GMLAN%20uses%20two%20120%20Ohm%20termination,be%20less%20stable%2C%20and%20communication%20errors%20may%20occur

.

 

[PHENDERSON]

Oh, the first time I ran the engine I did get obd data but no gauge clusters worked.

 

[Blizzard25]

The running bad could be a result of the high speed data network not communicating correctly so you need to fix it right instead of trying to shortcut things.

Here is a troubleshooting guide fire the network

https://resources.aeswave.com/ATG-05_Network-Diagnostics-and-Module-Programming.pdf#:~:text=High%20speed%20GMLAN%20uses%20two%20120%20Ohm%20termination,be%20less%20stable%2C%20and%20communication%20errors%20may%20occur

.

If the network wasn't terminated the bus would likely be noisy, not non-existent. Non-existent is usually when you have either a disconnected ground or a wire that's causing a connection making too many resistance points.

CAN (and GMLAN) are essentially differential transmission lines, they act as antennas if they aren't terminated. They're also twisted pair references so they need a shared reference ground.

OP since you have HP Tuners, are you just unable to flash and log, or have you tried running an infolog to get your bus information and vehicle ID? Since you mentioned no voltage from OBD it probably won't turn up anything, but I'm curious.

 

[Gtstorey]

When I removed my terminating resistor by swapping in the Saturn Vue EPS, the symptoms I had sounded very similar. Running roughly, and at best intermittent connection with HPT and Tech 2. Not sure about the gauges, but I don't think they behaved to well either.

But now that I have reread the first post, it sounds like you aren't even getting 12v power at the obd2 port. "getting nothing for voltage or resistance between any pins". But you are going to have to get beyond "Im not good at reading wiring diagrams." Figure out the correct 12v power pin at the obd2 plug and check for voltage between it and a known good ground, even if you have to run another wire directly to the negative terminal on the battery. If you get 12V on the power supply, check for continuity to a known good ground for the ground pin of the obd2 connector.

Randomly checking for voltage/resistance between pins isn't going to get you anywhere.

 

[PHENDERSON]

I don't know if it's related but with a new voltmeter I'm reading voltage.

 

[Gtstorey]

I don't know if it's related but with a new voltmeter I'm reading voltage.

What does "reading voltage" mean? What pins? What voltage? Electrical trouble shooting is all about details.

Most of the 16 pins in the OBD2 connector are unused.