Oh Sorry about that. Attached the troubleshooting from the dealer now. I need to compare it to the one you sent me earlier.

Here is another slight update. After the car sat for a week I put it on the charger and was going to run some codes again to see if I could find the "isolation voltages" called out in the troubleshooter. I still can't find them but in scanning the codes I could see that I got a code for the Battery safety enable/disable being disconnected. So I swung around to the back and put it in, went back in and turned the ignition on and VRRRRMMM it start up again! GRRR... drove it around again, all is fine except that P1AF0 and P1AF2 codes for lack of isolation. As I expected when I turned it off no start/no crank/nothing again. It seems to indicate that there isn't something "set" in the computers blocking the start. ...more like there is a sequence of something to reseting things or trying the ignition before certain tests are complete. I repeated the process I thought I went through several times and can not get it to successfully crank again. Weird, I must say. I tried it again several 24 hour periods in a row, and then again after waiting two days. Nothing...

In all cases the battery contactors are commanded open, So whatever it is its preventing the battery from being commanded on to the 300V bus... But when it does work 2 different HV batteries have shown they will follow the commands and the drive motors work well commutating the 3 phases etc. ...like I said just weird.

As I noted before the procedure seems to involve disconnecting loads from the inverter module DC outputs until you ifnd the load with the issue (this assumes the isolation voltages show that the issue is not with the s 3 phase outputs, since the motors drive okay that seems to be the case). I can get past that first step though to prove its not the 3 phase loads without seeing that data. Odd that its not there on the scanner, I still think I must be missing something. Not sure what to do about that.

...more importantly though I'd like to understand what loads are what coming off the inverter. There is scant information of what each physical interface is... All I can find is attached in the word doc. Which one of these is the Air Conditioning Control Module called out in the procedure?

Relative to the scanner, I returned the Xtool, it seemed like a nice enough bi-directional scanner but I could not confirm whether the special function commands work and it came to the end of the 30 day return window. Since I hadn't even taken the plastic off the screen etc. I made the choice to return it. I was/am considering buying a GM tech 2 clone as suggested. From my research if I have to change out parts i.e. the inverter many are VIN locked and need to programmed is there a tool that will both allow me to read codes/send special function commands and reprogram a module? I read about other tools like VxDiag or MDI? ...I don't know anything about the differences/capabilities of those tools. ...any advice there would be appreciated as well.

Thanks!
-Tom

 

over on the Tahoe forum there's a few 100 page thread about the tech 2's and the other ways to flash modules if needed. I'll have to find it, but it's the best place to ask. it seems a bit of a hassle, but I do believe you can buy the laptop interface, pay for a 3 days subscription to gm to down load and flash the modules as needed without spending 3k$ on the dealer scanners. but they would know better as I've not done it.

honestly I think in the end most guys end up with both the tech 2 as just a handy stand alone grab and go scanner, and the other flashing stuff requires a laptop running older software or something like that. in the end you're like 500$ into just buying both. and if money is time, it's paid for itself in one use.


there's also a map of locations of tech 2 owners willing to help scan a local members truck.

https://www.tahoeyukonforum.com/thre...rs-map.127187/
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I'll look at the other stuff and see what I can fine. you're looking for what wire bolted to the under hood high voltage inverter goes where? seems like I've seen that diagram somewhere.

 

here's a good thread to ask your tech 2 related questions in. it's 99 pages long, so I just ask haha. I'm sure the answer is in there somewhere already but it is hard to find.

https://www.tahoeyukonforum.com/thre...rchase.111719/

 

An update on my saga... I ordered a VxDiag and set up an old laptop with windows 7 got Tech2Win running and now have a working Tech 2. Wasn't very straightforward, but it worked (it would be easier if I just read and followed directions, hint!) You have to install things in exactly the right order or licenses etc don't work correctly. ...and also use an old defunct laptop with all the virus scanners, etc shut off, so I am not worried about who or what it might be contacting...

...so then I find the half pack voltages on the motor controller 1 & 2 tab. When I go back to my Autel scanner (AP200 phone scanner like $50 on Amazon I see them). This scanner is SOOOO much better then Torque or the Tech 2 highly recommend it now that I can see the differences. But it still can't do what a tech 2 does with respect to commanding. It was fun to use the scanner to beep the horn or roll down the window!

So on Truck 2 when I turn the key to accessory the HV contactors close, on truck 1 they do not. If I turn the key to start I can see both request crank. On Truck 2 then it cranks and starts ...but on Truck 1 does not crank, and I get nothing, not a click or anything. If I disable HV i can command the contactors just fine, so again I am positive the battery is fine, but when all set to run (no codes anywhere in the system) no matter what I do the computer will not command the contactors. This is just weird to me because without applying HV it has nothing to measure to determine there is a fault to disable HV. So it does feel like a chicken and egg problem if the issue were a high voltage fault.

With the tech 2 I cleared the crash sensors (were not set) and 300v present DTC (also was not set). Still nothing.

There is a precondition the computer is reading I presume that is keeping it from issuing the contactor closed command. So far I haven't figured out a source of what that logic might be and what I can check to find the ultimate block.

I also disconnected the air conditioning orange wires and tested with an isolation tester. Both read and black have less then 0.1 MOhms of isolation to chassis which I suspect is the isolation issue (since its blowing hot air despite the temp setting this would all make sense), but that should be clear now, there is something else preventing the high voltage application in the computer. GRrrrr...

This thread though tells me it can be a ground or something. A local hybrid shop told me that in his experience when the fault condition clears a prius will start, but they often don't know what that condition was after resolving it. ...But all other data when I compare the 2 trucks seems comparable (i.e. there are no obvious differences between off and accessory on that should/could prevent contact closure). so is it a DTC preventing it? Another clue is the Tech 2 will not let me turn on the 42v enable, not sure why that is. Maybe I just have to do more looking closer... i.e. a ground might offer a very transient voltage drop on some signal enough to lock out the commanding sequence.

https://www.tahoeyukonforum.com/thre...cement.140503/

Once again any ideas here would be appreciated. Its common that people can't get these trucks to start, now that I see it I would bet its always because the system won't close the HV contactors (especially now that I see it will command the crank request independent of high voltage application), it would be really good to figure out what the verification of the sequence is. It doesn't appear I'm being blocked by a DTC unless I am missing one.

...journey continues.

 

thanks for the follow up. I was wondering about your truck.


if I get a min I will look and see if my software spells out the crank routine step by step, I'm not sure it does. I will say if you can find the official gm shop manual for these trucks that would be super helpful. I've see guys post screen shots of their for other vehicles and they seem handy and I've seen them being sold on the corvette boards for each year corvette. so I know they exist, just not sure how people buy them.


off the top of my head there's 3 contactors.. one for pos, one for neg and one for the charge resistor. if you've even messed with rc planes, you'll know the charge resistor. if you just connect even a 20v battery they pop like crazy. so like the neg contactor will close, and then the charge one, once the voltage comes up to pack voltage the pos is closed.

I'd start there, make sure the contactors are closing and you have good power thru them. it's possible they physically close but the contacts are worn out too.

you might have to pull the cover off the battery, jump the litte safety cover jumper and do some probing with a meter while you command the contactors to close. you might be able to see that with the tech 2 but I don't know what you'd actually look for.

since you rebuilt your pack I think you'll be OK not to grab the 300v and die lol

 

You are correct on the contactor sequence. From what I can tell once all three contactors have sequenced (i.e. neg, pre-charge to charge caps, then positve) and transitioned, they have fully energized the 300V system until it subsequently commanded off and the contacts are open. I believe the contacts have a soft start to hard, where by there is a time when they start and if there are issues with inrush or something they can reopen. But once they finish the close sequence I think they are on for the duration. In my case I am pretty sure they are never commanded into that start mode.

The issue with an isolation failure is you can have 300V to vehicle chassis which I suspect isn't an issue electrically for the car, but more so until someone puts them selves in between chassis and earth ground, eeeek. Hence why the system tries to prevent these conditions from being persistent.

Thanks for any insight you can offer! Just to shed a little more light on this. I can tell the command to close the contactor never is issued, there must be something the computer detects that prevents that sequence. Certainly it could be a relay signal or something that is upstream of the command. Right now I am playing with logging data and comparing the "good" truck to the "bad" truck to see if I can see what the difference might be.

There is "Contactor request system circuit command" whicc is a percent value. Always looks to be around 30%. I can't find any documentation on what that is, what its for, etc. I can see the "contactor request" go from open to closed and "contactor status" go from open to close when I turn the key to ACC on the good truck. ...and vice versa when I turn the key to "OFF". On the "bad" truck none of these move they all say "open" all the time. On the contractor open reasons, all are "no" except "contactor commanded open" on the bad truck.

Now that I understand all the orange wire and source voltages and things I am not afraid to confirm manual disconnects etc and go in there and work.

When I had the battery apart I completely tested it etc. Currently though I have the battery that is the GM battery that came with the "good" truck in there. through the 3 random starts I got on the bad truck and the good truck both batteries have functioned fine in both trucks. So with that I have some degree of confidence I have fully eliminated the battery as a contributor here.

Again thanks for any help anyone can offer! ...I appreciate all questions. As I learn something from all of them.

 

they things throw codes like crazy. it's kinda amazing it's not getting you why it won't close the contacts.

one thing I have seen in my tech 2 beside the accident reset, there's a theft reset. is it possible it thinks the key isn't right?
I'm not sure how you'd do it, but can you watch the request while remote start?

there was a thread a read a while back, I guy that the orange wires from inverter to tranny short to ground. he got codes and they were a pain to get to. they run above the tranny inside metal pipes for protection.

I do hope you figure it it out. on a side note a battery log under a 10amp load would be interesting to compare with the lithium log.

​​

 

I did see something in the theft section that said "Invalid" but I discounted it. Don't you get the yellow security icon on the dash if its tripped? Now I'll go look next time I get my scanner fired up.

Continuing to read, it seems pto indicate that one has to clear the "300V Present DTC" in the HPCM if you've repaired a condition. I think I did that, but can't remember so I will do that as well. ...but i see different things on this, if it is a DTC wouldn't it show a code? I see some people refer to P0076, I can't tell if that is the code that sets to lock out contactors closing? I don't see that code. ...but have followed the procedure below with no luck. I don't know what to make of SDGM stuff as to what could indicate that being the issue.

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Service hybrid system message with no CEL

#PIT4585E: 2-MODE (HYBRID) No Crank After Discharged Or Dead 12v Battery - (Nov 16, 2012)

Anytime a battery charger or booster pack is connected to the 12V battery, the ignition key should always be in the off position. If this recommendation is not followed, the Serial Data Gateway Module (SDGM) may not report "Crash Sense Failed" and the 300v Hybrid Battery Contactors will remain open until the Hybrid Powertrain Control Module's (HPCM) High Voltage (HV) DTCs are reset.

To reset the HPCM HV DTCs, please use the following procedure:

1. Make sure the 12 volt battery is fully charged.
2. Clear DTCs in all modules.
3. Under the Body Menu of the Tech2 select the SDGM Special Functions Menu.
4. Select the "Crash Sensor Reset" in the SDGM by pressing “Enter” then select “Exit” to the Powertrain Menu.
5. Access the HPCM Special Functions Menu.
6. Select "Clear 300V Impact Detection DTC" and press the “Reset” soft key at the bottom of the screen. Exit to the Special Functions Menu.
7. Select the "Clear 300V Present DTC" screen and press the “Reset” soft key at the bottom of the screen. Exit the Special Functions Menu.
8. Turn the ignition key to the "OFF" position.
9. Power "Off" the Tech 2 scan tool and disconnect it from the vehicles diagnostic connector.
10. Open and then close the Driver's Door to disable the Retained Accessory Power (RAP).
11. Wait for 3 minutes and then start the vehicle.

Note: If there is a P0C76 setting, disconnect the 12v battery. With both 12v battery cables disconnected from the battery, discharge the capacitors by holding the cables together for 15 seconds. Reconnect the 12v battery and perform the above procedure again. If the DTC still resets, follow SI diagnostics and call the General Motors Technical Assistance Center if needed.


ADDITIONAL SI KEYWORDSIT4585 draw drain electrical engine HCP M99 mode nocrank proactive SDG two unwanted voltage

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

 

I posted some screen caps in your other board post.
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but oddly, have you switched the 12v battery between the 2 trucks as a test?

 

you probably know all this but incase it helps.