- Jun 24, 2021
- Reaction score
Hey all, I'm looking for some help and thoughts on an issue I have been battling with my 08 Tahoe Hybrid. I recently had an issue with a collapsed AFM lifter so replaced all of the valves. Due to the cathedral heads I needed to remove the valve covers, Heads, Intake, Exhaust Manifolds, and the valley cover. In the process of doing the valve replacements I replaced the valley cover plate, the valves, the spark plugs and the gaskets. I also replaced the water pump as I noticed that there was a leak from the weep hole on the pump. Prior to removing any of these parts I disconnected the 12V accessory battery and then removed the disconnect from the hybrid battery. I had to pull the wiring harness from the top of the engine which runs from the left side to the right and connects to the Hybrid control box on the right side as well as the coils, fuel injectors, and a handful of other devices. There was 3 ground wires that were disconnected in the process which I have verified are all secure back in the original locations.
The problem I am currently facing is that upon reassembly the vehicle will not crank over. I get the radio and all other systems as though there are no problems. When I try to crank the engine I get no crank. I checked the power in the accessory battery which tests out at 13.2v. According to my scanner the hybrid battery has 12.4V (assuming that its the hybrid battery voltage that its showing me).
I get a Service Hybrid System on the DIC and no codes currently on the scanner. I have pulled and replaced the disconnect as well to ensure it was seated and clean.
Prior to the AFM valve issue the hybrid system was working flawless. Even during the AFM issue it had no problems.
Currently the scanner for voltage with key on shows:
vpwr ($00) 11.355
vpwr ($01) 11.355
vpwr ($02) 11.355
vpwr ($03) 11.355
vpwr ($05) 11.355
vpwr ($07) 11.355
With key off shows:
vpwr ($00) 0.049
vpwr ($01) 0.032
vpwr ($02) 0.000
vpwr ($03) 0.000
vpwr ($05) 11.562
vpwr ($07) 11.670
I believe that the first 5 of these vpwr are the hybrid battery banks and vpwr07 is the accessory 12v battery. These have lost some voltage since the last jump and testing.
I did jump the vehicle and used my multimeter to measure the voltage on the accessory battery at 13.4v and the vpwr ranged between 12.4-12.8v
I read that jumping the vehicle with the key on can cause the system to think that there was a collision which disables the crank. When I jumped the vehicle the key was off; however, I did turn it on after about 10 minutes charging to get the voltage levels. I can't imagine that this would have caused it to go into safety mode could it? I didn't jump the vehicle prior to trying to turn it over unsuccessfully. Only after it would not crank thinking that the voltage in the batteries may have dropped in the week it was disconnected while I was replacing the valves. I did check all the fuses with a multimeter to verify they were good and did not come across and bad fuses. I also disconnected and reconnected the plugs to the hybrid system after a visual inspection for corrosion or bent pins. Everything looks great.
I am at a complete loss on what to check or where to go from here besides finding a tech2 scanner to put the system in jump mode and disable the collision detection (if its on)... The scanner is fairly expensive and there are a lot of warnings about buying these and getting china knockoffs so thats obviously a concern.
Can anyone help or throw me some ideas on where to go from here?
Sorry for the long write up. I just wanted to give as much data as I could in hopes someone may have experienced similar issues or has some idea on what to do besides the tech2. I love this car but am pulling my hair out at this point.