u0100 help with troubleshooting

No problem! I genuinely appreciate you working with me in the right direction.

I especially appreciate the CAN network readings you took at the DLC. It helps my diagnostic approach to know how stuff like bad grounds changes readings on the network. I can explain why both lines were at 0V, but not so sure I can explain the zero ohms... Anyone following along is welcome to make suggestions!

Tyler wrote: Gotcha. The no crank symptom confirms a likely PCM issue. The U0100 code suggests that the high speed LAN is operational, but we don't know that yet.

Got a multimeter? There's a few quick checks you can do to give us a better diagnostic direction. First, turn the ignition on and find a 5V reference sensor under the hood. Something easily accessible. Pretty sure the MAP is right there behind the throttle body? Disconnect it. Connect your multimeter to B- and gently probe all three pins. At least one should have 5V.

You can also check for network integrity and activity at the Data Link Connector. First, leave the key off for two minutes. Find pins 6 and 14 at the DLC.

Switch the multimeter to ohms and gently probe 6 and 14 at the same time. What is the reading? We want to see around 60 ohms.

While at the DLC, turn the ingition on and switch the multimeter to voltage. Connect the meter to B- and check pins 6 and 14 separately for voltage. What are the readings?

I'm sorry for bringing up such an old post but I'm having the same issues and I really could use some help.. I just finished a big project on my 2014 Camaro SS and now its throwing codes U0100 and P0231. I've had my battery tested, I've re grounded all my grounds, checked my fuses, and reconnected my ECM twice and still having issues. The car will start and even sounds good (Appears to run Lean), But i'm getting the codes and a loss of power steering, Also the majority of my readings (RPM etc) aren't pulling up or being read on HP tuners... I check the voltage on my MAP sensor and its reading around 4.7 ish volts, BUT I just checked ohms between pins 6 and 14 and its ranging from -75 to -85 ohms (I'm guessing this is an issue?) Again sorry for bringing up and old post but i've been throwing myself at this for over a week with no avail, I just wanna drive my finished project

Could you tell us the project you just finished?was everything in tact beforehand?were you able to log normally before?

this looks like a job for bob can bus fault finder lol

3 Gens wrote: Could you tell us the project you just finished?was everything in tact beforehand?were you able to log normally before?

Sure thing, So i installed a new cam, New heads, new intake manifold, A new fuel pump, new torque converter and a flex fuel sensor. I also uploaded a new tune via HP tuners.. And no i had 0 issues prior.

chief eaglebear wrote: this looks like a job for bob can bus fault finder lol

Not quite sure what that is

Check out aes wave it is a Can bus fault Finder but wait till someone more experienced chimes in thanks

when you installed the flex fuel sensor did you connect it correct?
www.camaro5.com/forums/showthread.php?t=497750
also there are many grounds that were attached to the motor did you return all of them in the same manner. these cars are vary finicky.

also your fuses for your fuel pump

3 Gens wrote: when you installed the flex fuel sensor did you connect it correct?
www.camaro5.com/forums/showthread.php?t=497750
also there are many grounds that were attached to the motor did you return all of them in the same manner. these cars are vary finicky.

Yes, one of the few readings that are actually working on hp tuners is alcohol content so I know its hooked up properly.

And I have checked all fuel related fuses, (all fuses actually), I even swapped out my fpms relay. I've regrounded EVERY single possible ground.. im going crazy trying to figure this out..

everything i can find shows ground issues.
www.camaro5.com/forums/showthread.php?t=417367

www.camaro5.com/forums/showthread.php?t=402656

www.camaro5.com/forums/showthread.php?t=367987&page=2

Dylan1214 wrote: But i'm getting the codes and a loss of power steering, Also the majority of my readings (RPM etc) aren't pulling up or being read on HP tuners...

Are these symptoms constant or intermittent?

I check the voltage on my MAP sensor and its reading around 4.7 ish volts, BUT I just checked ohms between pins 6 and 14 and its ranging from -75 to -85 ohms (I'm guessing this is an issue?)

When was the HSLAN resistance reading taken, exactly? Abnormal readings like that may be normal if you took the reading with the engine running or the key on.

Also, which pin were you on when you measured MAP voltage? Engine off or running?

Again sorry for bringing up and old post but i've been throwing myself at this for over a week with no avail, I just wanna drive my finished project

No worries! In the future it'd probably be better to start a new thread so anyone else searching for fixes in the future will have an easier time finding it. But for now, let's fix your project.

When was the HSLAN resistance reading taken, exactly? Abnormal readings like that may be normal if you took the reading with the engine running or the key on.
Also, which pin were you on when you measured MAP voltage? Engine off or running?

So I get that reading (-750 - -850 ) when I check right after opening my door with motor off and key out, However I check again a couple mins later with door still open, key and motor off and it reads 002

And I checked the first pin of my map sensor which currently reads 4.93 volts

Dylan1214 wrote: So I get that reading (-750 - -850 ) when I check right after opening my door with motor off and key out, However I check again a couple mins later with door still open, key and motor off and it reads 002

Interesting. Is the ECM easily accessible? If so, leave your DMM connected across pins 6 and 14, and unplug all three connectors. Key out, door closed, wait a couple minutes and recheck the meter. Hopefully, it'll be close to 120 ohms.

UPDATE: I re uploaded a new tune hoping the old one had an issue.. I no longer have the u0100 code, Now i have P069E (Fuel Pump Control Module Requested MIL Illumination (SES, Pending, Current, History) and P0603 - Internal Control Module Keep Alive Memory (KAM) Error (Pending, Current)

At this point i'm thinking it has to be a bad pcm or fpcm

Interesting. Is the ECM easily accessible? If so, leave your DMM connected across pins 6 and 14, and unplug all three connectors. Key out, door closed, wait a couple minutes and recheck the meter. Hopefully, it'll be close to 120 ohms.

It only has 2 harness leading into it (E-38 ECM) but its reading 004 ohm

Dylan1214 wrote: It only has 2 harness leading into it (E-38 ECM) but its reading 004 ohm

Really? :blink: I need to be clear about this. You're connected across pins 6 and 14 at the DLC, with the key off and doors shut after a couple minutes?

If so, the CAN lines are still shorted to each other. Even if you have a PCM problem, replacing it won't fix this condition. :silly:

Tyler wrote:

Dylan1214 wrote: It only has 2 harness leading into it (E-38 ECM) but its reading 004 ohm

Really? :blink: I need to be clear about this. You're connected across pins 6 and 14 at the DLC, with the key off and doors shut after a couple minutes?

If so, the CAN lines are still shorted to each other. Even if you have a PCM problem, replacing it won't fix this condition. :silly:

Yes this is the case.

Tyler I learned something new a few weeks ago when looking into a Bosch ADS625 purchase. The battery voltage reading. IF you're taking a scan reading from the OBD II port and have less than 12volts you can get erroneous network and other codes.


Would it be possible in this situation? The only reason I ask is I haven't seen it brought up. Also in this thread from the OP and the 2nd post added in when speaking of taking measurements from the mentioned pin numbers on the port is it those pin #'s counting from the right or left.

You do this stuff probably blindfolded but I'm still learning the small details so my brain needs to be massaged with this info

Been a good read so far and how it's showing that heat is a enemy on these vehicles. To much stuff packed in such a small compartment. My 04 Tahoe hasn't had these brittle wire / heat related issues yet, knock on wood. I'll run it until the body is like a Flintstones car just for the simple fact I get free oil changes as long as I own the vehicle. Only 124k miles on it so far.

If we have to change the engine later we can do that and still keep getting the free oil changes.

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Dtnel wrote: Tyler I learned something new a few weeks ago when looking into a Bosch ADS625 purchase. The battery voltage reading. IF you're taking a scan reading from the OBD II port and have less than 12volts you can get erroneous network and other codes.

Would it be possible in this situation? The only reason I ask is I haven't seen it brought up.

Definitely possible! But in my experience, the battery voltage needs to be lower than that to cause network issues. Less than 11, closer to 10 usually. If the OP wanted to rule this out, we could have him attach a charger or jumper pack? But, with all the accessories piled on newer cars, I figure the battery voltage will almost always go below 12V KOEO. :silly:

Also in this thread from the OP and the 2nd post added in when speaking of taking measurements from the mentioned pin numbers on the port is it those pin #'s counting from the right or left.

It's not necessarily right or left, but just facing the connector itself. I usually remember by finding pins four and five, middle of the 'fat' half of the connector. :lol: 16 is always at the skinny end of the other half. From there, I count out the pins I want.

You do this stuff probably blindfolded but I'm still learning the small details so my brain needs to be massaged with this info

Nah, not blindfolded. :silly: I actually use the scope far more often for network stuff, but I'm trying to get more comfy with the DVOM for this type of testing, because that's what our members usually have available to them.

Yes this is the case.

Weird. :blink: I can't figure why this network would be shorted together after your repairs. Is the ABS module accessible? That's the next module on that leg of the the HSLAN that's not dependent on vehicle options. Disconnect it and recheck your reading at the DLC.