2008 Tahoe Hybrid sitting for months...

[wjburken]

I would have no problem making an individual cell charger or making a 300V+ charger... if I had to go that route. I'm going to try the onboard Jump-Assist first. I just need to get a Tech 2.


I'm not sure I understand your remote start button comment --- I think 2x lock then start button is to remote start procedure, not to put the system into Jump-Assist.

Are you sure you need a Tech-2 just to jump the vehicle using another vehicle with a 12V battery? In looking at the manual for your vehicle, it shows how to jump with a 12v vehicle but doesn’t mention anything about needing a Tech-2. The post from another forum that I shared mentions the Jump-Assist, but I’m not sure that’s the same thing as what is outlined in the manual. I’ll admit, I don’t have a Hybrid and am only going off of what I read in the owners manual for your vehicle.

 

[bbOOmm]

Are you sure you need a Tech-2 just to jump the vehicle using another vehicle with a 12V battery? In looking at the manual for your vehicle, it shows how to jump with a 12v vehicle but doesn’t mention anything about needing a Tech-2. The post from another forum that I shared mentions the Jump-Assist, but I’m not sure that’s the same thing as what is outlined in the manual. I’ll admit, I don’t have a Hybrid and am only going off of what I read in the owners manual for your vehicle.

I have the original Hybrid Tahoe owners manual for the vehicle, I read the same thing. In several other areas in the HYBRID MANUAL, it describes features, functions and procedures of the gasser Tahoe, as if GM forgot to edit the sections for the Hybrid. This jump starting section in the HYBRID MANUAL is one of those forgotten sections I'm thinking, because it does not make any sense, especially after reading the Jump Assist procedure. The controllers have to be instructed to charge the hybrid pack. In normal operation, with the engine running, the vehicle generates 300V+ from the motor/generators in the transmission, then the 12V system is charged through a controller. Not the reverse.... unless in Jump-Assist mode. There is no engine driven generation of 12V as it is with a gasser.

The errors in the HYBRID MANUAL add to the confusion to MANY issues. Like..... WHERE THE EFF is the fuses or circuit breakers for the AC compressor? The manual references a 300V electric compressor, but yet references the fuses for the gasser 12V AC system.

 

[BG1988]

I would have no problem making an individual cell charger or making a 300V+ charger... if I had to go that route. I'm going to try the onboard Jump-Assist first. I just need to get a Tech 2.


I'm not sure I understand your remote start button comment --- I think 2x lock then start button is to remote start procedure, not to put the system into Jump-Assist.

just make sure the key is off position when attaching the 12v+ or a new battery

or you set off the crash detection system, that will disable the suv from being started(it would have to be reset then )


for the a/c system
it's in the HV battery most likely since it's tied into the HVDC system i guess Fusible Links?

 

[bbOOmm]

just make sure the key is off position when attaching the 12v+ or a new battery

or you set off the crash detection system, that will disable the suv from being started(it would have to be reset then )


for the a/c system
it's in the HV battery most likely since it's tied into the HVDC system i guess Fusible Links?

I was thinking it would be in the HV battery enclosure, but looking at the exploded view of the HV system as a whole, the 300V AC compressor has a short wiring harness that goes to the hybrid controller / inverter. I remember taking the plastic cover off that unit ( Under hood, rear ,passenger side) just to see what was hiding under it, long ago, There is an aluminum box basically, bolted up tight, nothing much more and the HV wiring going in and out of it.

Has anyone opened up one of these Tahoe hybrid inverters ? Pictures? Curious to see whats in it, how its constructed and if there are any fuses, fusable links, or circuit breakers hidden in there. Gotta be something. It seems unsafe to have HV wiring going places without any sort protection devices.

 

[BG1988]

I have the original Hybrid Tahoe owners manual for the vehicle, I read the same thing. In several other areas in the HYBRID MANUAL, it describes features, functions and procedures of the gasser Tahoe, as if GM forgot to edit the sections for the Hybrid. This jump starting section in the HYBRID MANUAL is one of those forgotten sections I'm thinking, because it does not make any sense, especially after reading the Jump Assist procedure. The controllers have to be instructed to charge the hybrid pack. In normal operation, with the engine running, the vehicle generates 300V+ from the motor/generators in the transmission, then the 12V system is charged through a controller. Not the reverse.... unless in Jump-Assist mode. There is no engine driven generation of 12V as it is with a gasser.

The errors in the HYBRID MANUAL add to the confusion to MANY issues. Like..... WHERE THE EFF is the fuses or circuit breakers for the AC compressor? The manual references a 300V electric compressor, but yet references the fuses for the gasser 12V AC system.

this it's not inside of the inverter but it's still good information

​

 

[bbOOmm]

this it's not inside of the inverter but it's still good information

​

That video helped a bit. Now I see the cover the comes off to get access to the wiring for the two motor/generators. Towards the front of the inverter under that now removed cover, theres some device there. If I'm remembering correctly, that is about where the AC HV wiring enters the inverter, so MAYYYYYYBE, that device is the a fuse, a fuseable link or a circuit breaker for the HV AC compressor. Cool, something for me to look at when I get home. I was worried because there is a totally separate cooling system for the hybrid system, I didn't want to unbolt something and have a mess on my hands trying to seal it back up, the video showed the access cover.

 

[dnt1010]

I understand your concern about the Hybrid battery being dead but maybe it is OK? I would probably charge the 12V under the hood first before going to a lot of extra trouble and expense. The issue with the crash detection shutting down the system is REAL what I would do is disconnect the 12V battery cables and charge the 12V battery independently of the vehicle then once fully charged, remove the charger and reconnect and give it a try.
If that simple and cheap procedure fails then to me the key information is that you believe that Hybrid battery already needed to be replaced and maybe just go ahead and do that? Sometimes the simplest plan is the best?