2008 Chevy Tahoe Hybrid - problem: engine won’t start

[sterile sand]

Hello, I have a Tahoe which was working one minute then the next it made a sound, that seemed like something snapped near the engine/bottom of the car and powered off completely. This was about 2 minutes after I started the car and let it sit there to warm up. I tried to start it again after a minute of waiting, the engine did not want to start at all. To this day after a month and a half of letting the car sit there, it still does the same thing. If anyone could suggest what the problem could be please let me know, thank you. (This is my first time dealing with car problems and car has not been used roughly for this to happen.)

[molten path]

Any chance you can tell us what happens when it tries to start? Cranks but doesn’t turn over? Clicks but doesn’t crank? No clicking but lights come on? Nothing at all?

If possible, hook up a scanner and see if it’s throwing any codes, that can help guide troubleshooting as well. Similarly, if you have access to a multimeter or voltmeter, a battery test is likely where we are headed

[sterile sand]

All the lights turn on and everything works, it’s just the engine I believe. When I turn the key, it turns all the way but nothing happens other than a little humming sound, but I believe that is normal and was there before the incident. It also shows the check engine light.

[molten path]

can upu post a video trying to start it?

[sterile sand]

Sorry if this is not a clear video, I turned the key all the way and nothing other than a little humming.

[molten path]

Even though the lights come on, battery is suspect. Can you pull it out and have it tested at a local parts store, if you don’t have a voltmeter?

[sterile sand]

I could try, another reason i didn’t think it could be the battery is because we just bought this battery about a year ago. So it’s about new still?

[lucid slate]

After it happened would it crank at all

[sterile sand]

No, just like how I recorded it. It did nothing at all other than humming.

[sick dirge]

GG @sterile sand, you just advanced to level 1! Chat more to level up and earn top roles!

[tropic compass]

How in the fuck did you find a hybrid of those years? Those things are RARE

Not 100% sure on size but I think a 24mm socket and breaker bar fits on the balancer, try to spin the engine by hand

[lucid slate]

That's what I was heading towards

[sterile sand]

It’s a 2008 car, we got the car in 2009. It’s been a daily sense, so it’s been used a lot. Also shouldn’t I be more concerned on why the car won’t even try to start the engine with the ignition when turning the key? Isn’t it one of the first steps into starting the engine? (Sorry new to dealing with car maintenance)

[tropic compass]

It tells us the engine is fine and that you might just need a starter, but if the engine doesn't spin you have big issues

In 6 years they made 70,000 hybrids of the tahoe

[versed iron]

crank it like soulja boy

[molten path]

Vagatoro - the month and a half of sitting is partly why I’m suspect on the battery, despite it being new.

[tropic compass]

Been there done that, get a trickle charger

[sterile sand]

I see, letting it sit does mess with the battery. Thanks for reminding me of that, so I will see if I could get it tested.

[sterile sand]

I hope it’s nothing too big, but I feel like it might because I heard something kinda snap and then it completely turned off when it was running just fine.

[jovial gull]

Like a really loud snap?

[sterile sand]

Like medium, not to loud but not to quite. To a point where it was easily noticeable.

[jovial gull]

Inspect the ignition switch/wires. There may be loose connections or mice or other animals have chewed enough of the wiring to have snapped or is completely broken under the electrical load.

[sick dirge]

GG @jovial gull, you just advanced to level 3! Chat more to level up and earn top roles!

[jovial gull]

Even if it is a battery fault. Maybe the humming sound is the battery trying to send power to the motor or the key switch trying to get the ignition to work

[sterile sand]

I thought the humming sound was the gas getting sent to the engine to prepare it, to start when tuning the key before turning it all the way

[jovial gull]

And no leaks?

[sterile sand]

Nope nothing is leaking from the car

[jovial gull]

Have you checked wires, fuel pump, that sort of stuff yet?

If you can find it*

[sterile sand]

I have not tried anything yet on the car, I am planning to get as many suggestions before looking into it completely

[jovial gull]

So you have not looked at the engine or beneath yet? Anyway i think its either the ignition fault or something with the fuel pump. Imma be right lemme check smt rq

Do you smell anything weird in the car or next to the motor?

At this point it could be somthing simple like a faulty starter or different problems at the same time. Let me sum up what i think may be wrong and you should look into:

• faulty starter
• bad alternator (the most common)
• some wiring for the ignition loose or broken
• fuel pump failures (i don't that explains the humming sounds
• on newer models (from 2001) the ECM/PCM receives a start request signal from the ignition switch, the sends the start signal to energize the starter circuit after confirming the correct status inputs. So be certain tha transmission is in park and e-brake is applied (may be different to your 2008 hybrid)

all these problems may differ because its an hybrid

[tropic compass]

It might be the ignition switch, a quality scanner could tell you real quick

My 03 would go to run but start died

[jovial gull]

He probably doesn't have that. I don't understand why he didn't look in the car first before coming here

[tropic compass]

Holy fuck the hybrid battery is 3k

[molten path]

The more of our questions you can answer, the better this works. Depending on your answers, that helps us narrow down your troubleshooting

[jovial gull]

Anyway, i just invested my evening helping ya so i hope that' enough. The other guys can help you further. Goodnight

[tropic compass]

It also doesn't have a "starter" per say, hybrid crap using a motor

[jovial gull]

@sterile sand

[jovial gull]

I know. I just summed up the most common problems as it could be somthing related

[tropic compass]

Oh that's terrible, it has AFM/DOD AND the hybrid system gm WHY

[sterile sand]

Alright thank you for trying to help

[tropic compass]

"If the vehicle is to be stored for more than 20 days, the 12-volt battery should be disconnected. If the vehicle is to be stored for more than 60 days, the 12-volt battery should be charged to capacity no less than once every 20 days."

[sterile sand]

Alright got that noted thank you

[sick dirge]

GG @sterile sand, you just advanced to level 2! Chat more to level up and earn top roles!

[sterile sand]

Sorry if I am explaining or saying things in a random why, I had never dealt with car problems myself and had other people do it. I want to try to do this one on my own.

[tropic compass]

Hell of one to start on, hybrids can be complicated. Do you have some sort of automotive scanner?

[sterile sand]

Ya I knew this was gonna be a challenge because even the people I take it to have a hard time with the car, one of them couldn’t even figure out what the problem was. And no I do not have a scanner, I am new.

[jovial gull]

Maybe lend a scanner from a dealership or repair shop as they aren't cheap (atleast in my country)

[sterile sand]

Ok I will try to get my hands on one to Check

[molten path]

So in summary I think we have three things to do: 1. Get your hands on a scanner of some kind to see if it’s giving trouble codes. 2. Pull the 12v battery and get it tested. 3. Use a socket and breaker bar and try to rotate the motor, to see if it even moves. Mango and Malteser, that about sum up?

And one detail to confirm, Vagatoro: did this suddenly die while driving?

[tropic compass]

Yes

[sterile sand]

No it died when I turned it on, I had it running in the driveway for about 2 minutes before it just completely stopped

[sterile sand]

But this is a good first thing to start on and see what’s wrong. Thank you

[versed iron]

Can't wait to see where this goes. The mysteries of the motor that suddenly stopped

[sterile sand]

Also quick question, since I am new. I was wondering is it ok/ possible to slap on a turbo on a 6 liter V8? And have it work just fine? Or will there be problems because of the type of engine it is?

[tropic compass]

You can, needs a tuner

Maybe a transmission

[sterile sand]

Ok, thank you. I was thinking on adding one just for fun when I get enough money for all the parts.

[versed iron]

Ls2? Yeah go for it. Just get a tuner to tune it and happy days.

[molten path]

I didn’t know this until I wanted to read how this hybrid Tahoe works, apparently that is an LFA engine. Unique to the hybrid GMT900 trucks, all aluminum!

So this is an Allison AHS2 unit, basically instead of a regular transmission (input shaft, clutches, planetary gearsets, output shaft) it also houses two electric motors/generators inside the transmission as well. https://en.m.wikipedia.org/wiki/Global_Hybrid_Cooperation

[sterile sand]

I knew It had an electric motor because it is a hybrid it’s meant to save a little gas by using electricity for small speeds. But I did not know it was in the transmission itself.

[molten path]

Yeah this truck is definitely fascinating. I remember when they came out, I remember a GM rep at a car show being completely unable to explain what “two mode hybrid transmission” means. Bob Lutz was pretty proud of this bit of engineering, at least as he recalled in his book. And I’ve never had the chance to work on one. You have in your hands a genuinely unusual and fascinating bit of automotive history.

[sterile sand]

Thank you very much, I love this car so much. Which is also the reason why I am going to try my hardest to never let this car die.

[tropic compass]

👀 GIVE ME THAT ENGINE

[sterile sand]

Sorry but I need it to run my car 😅

Also I cranked the engine by hand and it seems to feel just fine. So I believe the engine is just fine

[jovial gull]

And how is it going @sterile sand ?

[sterile sand]

So far I don’t think anything is wrong with the fuses and the engine seems to be smooth when I manually cranked it

[sick dirge]

GG @sterile sand, you just advanced to level 3! Chat more to level up and earn top roles!

[sterile sand]

Haven’t checked the battery yet

[jovial gull]

Check the starter motor when you have the chance

But if its the starter motor how did it suddenly die

[molten path]

@sterile sand usually when you turn the key to On right before you crank the engine, you can hear the fuel pump hum for a few seconds to prime the system. I don’t hear it in your video but it might not be loud enough for the video to pick up. Are you able to hear that? As a reminder, we are also interested in making sure the battery is tested (probably ok but good to confirm) and seeing if you can get a code scanner hooked up to it to see if it has any trouble codes that can guide the troubleshooting.

[sterile sand]

That’s what I was thinking, it had to be something else I believe because it just completely died when that noise happened

[sterile sand]

Yes I do hear the humm, so I know that’s fine. But I still need to buy or borrow a scanner

[jovial gull]

My guess its something that went wrong that made the car shut itself off

[serene epoch]

Check that the starter is completely connected, as in all wires connected

sounds stupid but hey I got lucky once

unsure how it got disconnected but it sure was the problem

[tropic compass]

Hybrid doesn't exactly have a starter, it's in the transmission

[serene epoch]

you right

[molten path]

Just as a sanity check, ground cable to the engine. If it was loose/corroded/questionable then that coming loose could cause it to stop and not start, and the rest of the electrical system would appear to work ok.

[sterile sand]

That could be it, I am going to get the battery tested tomorrow to be sure if its also the battery or not

[molten path]

Awesome. While the batteries out you might have better visibility to follow the negative cable

[sterile sand]

Alright, I will try that tomorrow. Thank you

[versed iron]

Did we figure out what the snap noise was before the engine cut off?

Man this is the most exciting thread I've gotta say. So keen to find out the outcome

[sterile sand]

Nope, everything on the out side looks ok, so I think it must have to do with something on the inside

But don’t forget that I am new, so don’t be surprised or upset if I can’t get it myself.

But even if I can’t do it I will still try to get it fixed, so one thing for sure is I’m going to try to get that car running again!