Power to the heaters must come from a switched source, not constant B+. I don't know any other way to explain this, it doesn't seem to be getting through.
Power to the heaters must come from a switched source, not constant B+. I don't know any other way to explain this, it doesn't seem to be getting through.
You were warned.Originally Posted by gtstorey
do an amp draw test on the system with everything off and if its excessive then unplugg the HEGOs and recheck. if the draw goes away then you know theyre wired incorrectly. If thats the case then follow the heaters circuits back to the issue. I know most people dont like electrical but, it seems fairly straight forward to me.
Amp draw isn't even really necessary at this point since we know the O2's are hot. I would check for one after repairs though. I would grab a volt meter or a test light for a quick test - unplug the extensions then see if power is present at the fuse with key off - after this back track to the switch. Willing to bet when it's all said and done we find the ecm isn't getting power everywhere and something's shorted...
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
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I swear electrical diagnostics will be the death of me. I dont understand electrical at all and its really frustrating.
Thanks for the help, Blindsquirrel and I apologize for how caveman my electrical diagnosing skills are. But I get what you are saying now. Power must come from a switch source not constant otherwise the o2 sensors will always be energized.
gtstorey yes I know I was warned, I did it on purpose to test lol
GHuggins, If the ground and power wires to the o2 sensors are flipped, wouldnt that cause the sensor to always be energized regardless of having the key on? Further more, if the signal high and low wires were flipped, wouldnt that also prevent the ecu from reading the signal? I checked all my fuses and they were all intact. If the extensions were wired incorrectly, it strikes me as odd that they would make the same mistake back to back. Although when I was checking power under the car, the harness plug would show power at the top right corner (iirc) but wouldnt show power in that same spot on the o2 sensor end of the harness extension. Correct me if im wrong but the extension should have the same wires in the same location at the o2 sensor plug end of the extensions as the harness plug does, right? If they were wired incorrectly on one end, I could just depin both harness extensions and move the wires to the correct spot.
There shouldn't be any of the 4 wires at any of the O2s that have power of any kind with the key off. It's not a mis-pinning issue, none of those wires should be hot. This is something wrong at the fuse box, or a whole mess of wires shorted to battery+, which is pretty unlikely. You need to find the fuse that powers the O2 heaters and figure out if it's constant or switched, and make sure pulling that fuse kills the power to the heater circuits (if they stay hot with the fuse out, they're getting power from somewhere they shouldn't).
Electrical is exactly like plumbing, but with invisible water. Wires are just pipes that flow electrons, relays are remote-operated valves, etc.
thanks for your help blindsquirrel. I left my car at my new house a few days ago and wont be able to mess with it until this Wednesday. I did come across something perplexing. My O2 sensors work when they are plugged into the rear o2 sensor plugs. Dont ask me how. I came to this realization because I found a ton of backed up logs dating back to 2021 which was the first year I had the car. The car came with some old long tube headers and an old and rusty exhaust. I ordered the 1-7/8ths headers and true duals exhaust along with the harness extensions. I ended up not using the extensions because I saw the o2 sensors were plugged in, although I didnt realize they were plugged into where the rear O2s go. After I pulled the motor and installed the 6.0 I rebuilt for it, I also installed the harness extensions. I saw two un-used plugs on the harness on each side of the block and after a little research found out they were the plugs for the front O2 sensors (car was down for almost 18 months at this point and forgot the sensors were working and assumed they must have not been). After that, I could never get them to work again. But that just makes no sense at all and there are several posts where people installed long tubes and plug the front o2s into the rear o2s by accident resulting in their O2s not reading at all, showing a consistent 440-450 mv. Im going to include a log where you can see the O2s working, keep in mind there isnt much info as I was brand new to tuning back then and was just messing around logging stuff. Im going to give it a shot on wednesday and see if that works. If it does id be incredibly shocked.
screenshot.04-06-2023 16.40.41.png
See how both B1 sensors have the exact same wire colors, and both B2 sensors have the same wire colors? And the front-rear connector bodies are the same? This is why you keep getting told to verify which wires go where. The only way to really REALLY know whether a mystery O2 connector is a front or a rear is to find the other end of the wires. If it goes to 69/29 it's an upstream, if it's 68/28 it's a downstream. There is no way for you to plug in a sensor to the downstream connector and then have the PCM display that sensor's data as an upstream sensor - unless that downstream connector is actually going to the upstream's pins at the PCM. Not checking this stuff and then trying to figure out why it doesn't work right is why you are finding 'wiring stuff' to be so difficult. Check it, then you know, and once you know you can use logic to figure out why it's doing what it's doing and how to make it not do that anymore.
Of course this is all a separate issue and changes nothing about what's already been said regarding the heater circuits being powered during key-off. Need to trace those wires out too. Step 1: know, then Step 2: fix, and if you don't check stuff needed for Step 1 you never make it to Step 2.
F-body front O2 connectors are up by the motor mounts. Rear O2 connectors are further back by the transmission. Pretty hard to get them mixed up on that platform. Just go get some 00-02 Vette rear O2s and use them. Same sensor with the F-body connectors and they have 30" long leads on them and will eliminate the need for extensions. Bosch part# 13111. It's what everyone has been using on 4th gen F-bodies for years. I've installed tons of them on 4th gens with long tube headers.
Mystery solved. I connected my front o2 sensors to my rear o2 sensor plugs and the bitch starts trimming the fuel. So now it goes into closed loop no problem. I guess the previous owner had issues with the front o2 sensors and just swapped wires with the rear since it had long tubes installed when I bought it. Thats the first ive ever heard of anyone doing that and its kind of ingenious, not gonna lie. I attached a log if youd like to take a look at it. For some reason the fuel trims were pretty much maxed out trying to pull 25% fuel but my wideband was readuing 23:1 AFR. For some reason my iac steps start at around 180 and start creeping up from there until it gets to 300-310 steps where it all of a sudden pulls timing down to 4 degrees, resetting fuel trims back to 0 before iac counts start going back down and timing goes back up to normal. Really strange and not sure why it does that, im thinking its something to do with the throttle body. Its super old and after the 2.5 hour drive to my new house the idle would stay at around 1100 full warmed up when target is 900. I also noticed the tps wants to stick sometimes around .8-1.4% causing a really weird idle and increased rpms. I ordered a new 102mm tb that should be getting here any day now. Im just glad my o2 sensors are actually reading.
Well after taking a closer look to the log and not rushing through it trying to get finished, I realized that the fuel trims are populating but the O2 sensor voltage is bouncing from 440-460. So now that I know the sensor are reading, I have no idea why they are not fluctuating. And it is affecting my car because it?ll go from 16:1 afr to 20-22:1 afr. Looks like the fuel trims just keeping trying to pull more and more fuel out and I don?t know why.
If the sensor is attached to the wires that go to PCM C1 69 & C1 29 then the PCM will read it as B1S1, it doesn't make any difference where under the car the connector is. The wires from 69 & 29 could be extended and rerouted to the right rear taillight area and that would not make it a right rear taillight O2 sensor.
You need to do what's called a bypass test. Apply ground and then power to what you suspect is the B1S1 sensor signal terminal at the harness-side O2 connector, with the sensor unplugged, while watching the B1S1 value in the scanner. Applying ground should pull the ~450mV bias voltage down to under 100mV. Applying power should drive it high to over 800mV. If you can't make it do either of those two things you aren't on the right wires, or the PCM is dead.
I went ahead and did that. No matter what I do, I could not get the voltage to change by simply jumping the signal high to ground or the signal high to voltage using a screwdriver. I was only able to get a voltage drop down to 2 when I connected a cable to my negative terminal on the battery and jumped the signal high and ground. Idk if doing that is incorrect but I was not able to get results otherwise. As for the flip side, I couldn?t get the voltage to pin its max value. It?s quite frustrating honestly and Im starting to wonder if doing this is even worth it in the end for my setup.
Well I finally figured it out. Turns out the previous owner DID swap the front and rear o2 sensors at the ecu. So front plugs report as rear and rear plugs report as fronts. After chasing fuses and electrical stuff, I gave up and plugged them back into the rears. When I looked through the tune, I realized CL was disabled so I enabled it for shits and gigs thinking it wouldn?t do anything. Well I was wrong because now they read as B1S1 and B2S1 in the scanner and my AFR IS RIGHT AROUND 14.7. I did a search and only found 1 other post where the rear o2 plug went to the front o2 pins on the ecu. What a headache! Oh well, off to learn how to tune CL. Thanks everyone, I appreciate everyone?s help and suggestions!
That is a perfect explanation of a complex system! Cool. Mixed up primary and secondary sensors, lol.
Turn on the kitchen sink and wonder why the bathroom water starts running lol.
Last edited by Hondaeater; 07-30-2023 at 05:41 PM.
Swapping front to back still doesn't explain why he had warm O2s with key off.
I forgot that was even a problem in this one. After they drag out over several months, It's hard to remember some of the details.
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