3 shops cant find the issue. 2017 Chevy Tahoe

[mrsunnym]

I am having a hell of a time finding the problem as I dont really get error codes, but here are the things that keep happening. I have an idea of what to do, but would love opinions and some help on how to do it.

I have gone to 3 shops.... none of them can find any loose wire or see anything, but I dont think they did a specific check on anything other than knowing the Battery is in good shape, but 4 years old.

Alternator puts out good power, but who knows if its consistent.

Grounds might be OK, but one could be an issue.

Steering assist motor could be going bad, but functions when they look.

Its been a long year but maybe some of the background helps or makes it impossible to diagnose.

1 - (April) water pump pully is going bad. I can hear it. So I have the water pump fully replaced.
2 - (April - days after water pump) Engine Temp stops reading
a) sensor replaced but get same issue, replaced 2nd time, same issue, code reset and shop says its a different problem, but sensor is good. does not happen

3) (August - till today) At different points the cars electrical 100% dies/reboots for ~30 seconds. happens every day to maybe every few days. Maybe 20 times I know of. When I go to shut the truck off by pressing the off button or just randomly based on the flows below everything goes dark and engine cuts out. about 30 seconds later the Chevy logo scrolls on the screen and car can then be started and driven normally. I get the notice to roll down passanger and driver window and up again so I know the BCM just rebooted. I get 0 codes in the computer.

- Turn into my house and pull into the garage, put it into park and press the off button (80% of the time)
- same as above, but cuts out before I press the button
- went to do a uturn and waiting to go, and as I take my foot off the brake it all dies
- Put it in reverse and it died after idling for 15 minutes before gear shift.
- More than once while stopped and turning the wheel or putting a strain on the system by using the steering assist I have gotten a warning about steering I think and then it died right after
- My lights do dim when I use the steering while parked in my garage

4) Nov - The Thermastat issue started again. Granted, the car rebooted and it clears the issue right away and has not happened again in a few days.

What should be a plan to identify the issue? I dont want to sell my truck!!





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[GMCnewbee]

There are some very knowledgeable people on this Forum that I am sure will offer you their thoughts and will help you out. The one thing that stands out to me in your post is the 4 year old battery that is "good". I just changed out my 3 year old battery because I do not want to get into any of the mystery electrical issues with these computer controlled vehicles. My advice, put in a new battery first!

 

[Fless]

There are some very knowledgeable people on this Forum that I am sure will offer you their thoughts and will help you out. The one thing that stands out to me in your post is the 4 year old battery that is "good". I just changed out my 3 year old battery because I do not want to get into any of the mystery electrical issues with these computer controlled vehicles. My advice, put in a new battery first!

^^^ This. Then have a voltage drop test done to verify that the main cables and grounds are good.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

Well..... That was a lot of text and detail, and I thank you for that. It helps us start to help you troubleshoot your issue.

We need to go through some basics first, related to what you have provided, and I know that may be annoying to you, considering all that you've been through, so far.

(1) 'Battery is in good shape'. For these trucks, a 4 year old battery is rarely in 'good shape'. Did you remove the battery from the truck and take it to a local auto shop with a battery bench load tester and have it load tested? (Not some in-the-engine bay, in-the-parking lot testing nonsense, but an actual bench load test) If no, get it done. Marginal-to-bad batteries are one of the most common sources of 'strange electrical' issues. Fact!

(2) Your truck is relatively new, but we don't know what it has gone through. Apart from the battery itself, the electrical wiring integrity and terminal connections (12V and especially grounds) are really important on these trucks. A loose connection, or a loose or corroded ground terminal will set off a series of intelligible issues on these trucks. So, at a minimum, check the battery terminal connections and the battery to ground and motor connections, to ensure that they are clean and tight. Note that these battery cables generally rot from the inside out, so an OHM impedance test may be necessary, if you see any unusual interior discoloration or corrosion.

(3) 'Water pimp replaced'. While the cooling system was opened up, was the thermostat and gasket replaced? Was the cooling system drive belt tensioner (if there is one for this model year) replaced? (A failing belt tensioner spring can cause a similar noise as a failing water pump). Also, was the cooling system properly 'burped' during the refilling process? If there air trapped air pockets, particularly around the coolant temperature sensor, your coolant temperature gauge wont read correctly.

These are just some initial thoughts/questions that I have regarding your issue, and please send us your thoughts/responses, so that we can continue to help you resolve your issue.

Other members of this Forum much more knowledgeable than me in this area will chime in.

 

[Badge]

Echo folks here; primarily sounds like bad battery, failing alternator and/or grounding issue. I know that sounds simple but those three things are all involved in your scenarios. That being said, with a new battery, and checked alternator, replacing the water pump is the main focus IMO as it impacts many electrical connections that have to be removed/replaced correctly. The starter battery main ground to engine block wire was likely removed; was is damage free and reinstalled correctly? Easy to take off, check, sand connections if needed and put back on. Hard to know if they bent, broke it especially if internally weak already but not a high probability. The alternator also comes off I believe so there are several other electrical connections that could cause these symptoms. And there is no joke on the need to burb (properly) the radiator system post working on that system and draining fluids. Just had a radiator replacement by GM dealer and it still through temp issues (blowed cold/hot) until I burped it myself. If everything electrical was put back together correctly on water pump replacement, then I’d focus on what seems to be a common variable of steering wheel turning. I’d reset/check the steering position sensor and BCM with tool or just try battery disconnect approach; take off BOTH positive/negative cables and touch together to drain residual power.…Leave unattached and no other power for at least 20 minutes. Literally at least 20 min. from experience. Then reattach battery cables and drive around town to let things relearn a bit. If still having same troubles after 20 min, then move on from BCM unless you have a tool to check it. Might also consider leaving a scanner tool attached (I have a tech2 to do this but older truck) and drive around to record/catch any errors before your system reboot assumably is clearing them. A good scanner should still find persistent codes but BCMs get tricking and don’t throw codes even when they should (i.e. stabilitrack issues). Replacing a BCM is easy, but not a cheap fix so you’d want to be sure its the culprit. Just some thoughts if it triggers better thoughts…

 

[Doubeleive]

I am having a hell of a time finding the problem as I dont really get error codes, but here are the things that keep happening. I have an idea of what to do, but would love opinions and some help on how to do it.

I have gone to 3 shops.... none of them can find any loose wire or see anything, but I dont think they did a specific check on anything other than knowing the Battery is in good shape, but 4 years old.

Alternator puts out good power, but who knows if its consistent.

Grounds might be OK, but one could be an issue.

Steering assist motor could be going bad, but functions when they look.

Its been a long year but maybe some of the background helps or makes it impossible to diagnose.

1 - (April) water pump pully is going bad. I can hear it. So I have the water pump fully replaced.
2 - (April - days after water pump) Engine Temp stops reading
a) sensor replaced but get same issue, replaced 2nd time, same issue, code reset and shop says its a different problem, but sensor is good. does not happen

3) (August - till today) At different points the cars electrical 100% dies/reboots for ~30 seconds. happens every day to maybe every few days. Maybe 20 times I know of. When I go to shut the truck off by pressing the off button or just randomly based on the flows below everything goes dark and engine cuts out. about 30 seconds later the Chevy logo scrolls on the screen and car can then be started and driven normally. I get the notice to roll down passanger and driver window and up again so I know the BCM just rebooted. I get 0 codes in the computer.

- Turn into my house and pull into the garage, put it into park and press the off button (80% of the time)
- same as above, but cuts out before I press the button
- went to do a uturn and waiting to go, and as I take my foot off the brake it all dies
- Put it in reverse and it died after idling for 15 minutes before gear shift.
- More than once while stopped and turning the wheel or putting a strain on the system by using the steering assist I have gotten a warning about steering I think and then it died right after
- My lights do dim when I use the steering while parked in my garage

4) Nov - The Thermastat issue started again. Granted, the car rebooted and it clears the issue right away and has not happened again in a few days.

What should be a plan to identify the issue? I dont want to sell my truck!!





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you probably have at least 2 different issue
1. possible bad/stuck thermostat
2 electrical issue, check battery cables/grounds, check starter power cable-(can be burnt and/or touching other nearby metal), check grounds under engine/engine/power steering
check for pinched, chaffed wiring-mainly under the bottom edge or anywhere wires sit/rub on the body or engine
there are a couple tsb's for key locations to check for pinched or chaffed wiring other then around the engine.