C5 comm problems
C5 comm problems Alright, so I hope you guys can help me out because I'm just out of ideas on what to do with this problem.
Problem: After installing a HCI on my 2002 C5 corvette M6, I go to my local tuner, Newtech in northern California for a tune. After trying to connect his to Hp tuners to my OBD2 port, it can't detect the pcm or vcm.
What I know: The OBD2 port has power (powers the code readers), Code readers read codes just fine, and the 5 wires behind OBD Port are in good condition.
PCM was bench tuned after my first visit to the tuner, car runs fine without any dash lights or anything right now.(PCM isn't fried)
Fuses for the ALDL, BCM, PCM, and both cigarette lighter fuses are fine.
There are no codes in the DIC.
I tried a new battery just in case the old battery had a bad cell or something, no help.
Only thing that I can think of is that it has a short in the one of the two connectors next to the BCM or the dark green #58 wire on the PCM is somehow messed up or not connected.
Let me know what you think, any help is appreciated.
TECH Fanatic
Joined: Jan 2018
Posts: 1,059
Likes: 198
You should ask your first tuner if they locked the PCM.
If that's not the problem, then consider replacing the PCM. There's an ebay vendor named spareecm selling 0411 PCMs for about $90 (I have one on my desk as I write this), or you can get them cheaper from a junk yard.
If that doesn't fix it, then you have a wiring problem.
Or maybe check the wiring first... there are really only 4 wires that you need to talk to the PCM through the OBD2 port:
http://www.gmtruckcentral.com/articl...h-harness.html
My guess, based on the fact that everything else works, is that your PCM was locked by the previous tuner, but that's just a guess.
If that's not the problem, then consider replacing the PCM. There's an ebay vendor named spareecm selling 0411 PCMs for about $90 (I have one on my desk as I write this), or you can get them cheaper from a junk yard.
If that doesn't fix it, then you have a wiring problem.
Or maybe check the wiring first... there are really only 4 wires that you need to talk to the PCM through the OBD2 port:
http://www.gmtruckcentral.com/articl...h-harness.html
My guess, based on the fact that everything else works, is that your PCM was locked by the previous tuner, but that's just a guess.
The pcm was already bench tuned with his hp tuners device. Concluding that the pcm is fine and unlocked.
i did some research on the five wires on the obd2 port, why is one of the five wires attached to the stereo system?
i did some research on the five wires on the obd2 port, why is one of the five wires attached to the stereo system?
when I run into something like this I suspect something in the Data stream that's messing things up.
find the serial data bus and disconnect wires one at a time until you get the PCM to communicate
Radios are a known trouble spot so start there first
find the serial data bus and disconnect wires one at a time until you get the PCM to communicate
Radios are a known trouble spot so start there first
Update: checked the voltage for battery vs DIC reads and the battery reads 12.2-12.3 while the DIC reads 11.6-11.9. Is this a ignition switch problem?
also checked the OBD 2 port pin 16 for power and it read 11.8-11.7, but how do i check the other 4 pins? Is it in ohms for resistance or volts for reference?
also checked the OBD 2 port pin 16 for power and it read 11.8-11.7, but how do i check the other 4 pins? Is it in ohms for resistance or volts for reference?
TECH Fanatic
Joined: Jan 2018
Posts: 1,059
Likes: 198
You would not be the first person to be stung by this: https://forum.hptuners.com/showthrea...er-lock-bypass
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