Electrical - where to begin

[MassHoe04]

rockola 1971:

The only thing I’m trolling for is how to fix my damn rig!

The only reason I might not be able to perform tasks is my height (I am not tall) and lack of experience. Hence, my asking for help here.

I have ladders for getting into the engine bay. I can easily get under the car.

When you get to 70+ - call yourself whatever you like. You can thank me for giving you the incentive to learn something new today.

RESPECT! You got mine! Any female willing to roll the sleeves up and tackle their own repairs is really pretty incredible. Age and ability are not directly related, so to be a female that age bracket and tackle auto repairs on her own... WOW! That is rare.

Electrical issues can be tricky, but there are some real diagnostic wizards on the forum.
If you don't have one already, pick up a volt-ohm multi-meter and I am sure these folks will be able to walk you through what to look for and where.

 

[Moosemoon]

RESPECT! You got mine! Any female willing to roll the sleeves up and tackle their own repairs is really pretty incredible. Age and ability are not directly related, so to be a female that age bracket and tackle auto repairs on her own... WOW! That is rare.

Electrical issues can be tricky, but there are some real diagnostic wizards on the forum.
If you don't have one already, pick up a volt-ohm multi-meter and I am sure these folks will be able to walk you through what to look for and where.

Thank you. I do have a multi-meter. Not skilled with it yet but learning. Hopefully, between this forum and YouTube and lots of research - I’ll get something figured out.
Your respect is appreciated.

 

[Moosemoon]

I am in my last year as a septuagenarian, next year I will be a octogonsomething. All yall young folks are amusing to me.

octogenarian. Glad it’s entertaining.

 

[Moosemoon]

The air bag computer surveys the seat occupancy, seat belt buckle, descrete impact sensors and the circuitry connecting all these components. Normal resistance for the impact circuits has a range. I cannot remember the range, but it is something like 1.8 to 3.8 olhms on a reference voltage of 2.4 volts. Beee extremely causions when touubleshooting this system. Appars like a voltage above the 2.4 reference voltage exposes the air bag with a bang. As you see, I do not have spell checker. Disconnct the negative battery terminal and let all capacitors discharge.

 

[Moosemoon]

Thank you for the info. Sorry if I got a little defensive about the ‘entertaining’ post.
You have given lots of good direction about where and how to start.
Now if the wind will stop blowing here in Idaho ….
(that’s a joke - it’s almost always windy here)

 

[rockola1971]

I am in my last year as a septuagenarian, next year I will be a octogonsomething. All yall young folks are amusing to me.

Young? Im over a half a century old and been in 2 wars but.....Youve definitely been around longer than I have. My apologies. Someone else here has vouched for you. Hats off to you maam for taking care of stuff yourself. If I may be of any help. Just ask.
We are quite the clown bunch. Its impossible not to laugh at some of the things we have done in the past and spoken about on here.

 

[Moosemoon]

Young? Im over a half a century old and been in 2 wars but.....Youve definitely been around longer than I have. My apologies. Someone else here has vouched for you. Hats off to you maam for taking care of stuff yourself. If I may be of any help. Just ask.
We are quite the clown bunch. Its impossible not to laugh at some of the things we have done in the past and spoken about on here.

 

[Moosemoon]

First and most important - THANK YOU for your service!

Have seen your responses to some other elec ?’s. They made sense to me as well as the other suggestions posted here.

Hope to do some checking tomorrow. Will get back with results.

Another snow storm moving in tomorrow night. ugh

 

[Moosemoon]

Like @Donal said about 3/4 way thru the recommendations. Got to start somewhere and my money is on checking EVERY ground point connection for tight, corrosion and even if is connected at all. I personally would not advance far in to this till that "must know" item is done. That rig was somewhere else for 2 years and almost anything could have happened with the rig while in the hands of MR. SLOW MO! Diagnosing electrical problems, especially if intermittent, can be a nightmare and expensive. Hopefully someone here can supply a diagram of all ground points. If not, you can always pay $60 at ALLDATAdiy.com and get vehicle specific info and diagrams. Good luck.

Post where you are at and maybe a member can help personally or recommend a quality shop in your area. For instance, I know a great guy and shop in my area in the Willamette Valley of Oregon.

Thank you for your service!!!

I am beginning to check grounds tomorrow. Will post any resukts I find.

 

[Popeye101]

A lot of imagination required here, so resort to basic operation. Check engine oil, coolant levels, adjust if needed, belt tension.
Insert ignition key and rotate to ON position. Note 7 flashes of air bag icon, air bag icon stays on or not. Start engine, noting oil pressure, coolant indicated, fuel level indicated. Check under vehicle for drips/ leaks, etc. All good sofar. Note CEL on or off or flashing. CEL not flashing, operate normally. Note oil pressure, coolant temperture, fluctions on any gauge, etc. Take the vehicle through several short trips to cycle through ignition on/off, engine run, engine off. If the CEL light is on, use your scanner to identify and RECORD error codes on paper.
Apparently you are in a area where dianogistic services are in very high demand and no one has time to assist you. Most all of the members on this forum are willing and able to assist, if your location was known, some near you may be able to do hands-on assist.
Note that the vehicle was neglicted for almost 2 years and sufferes neglected vehicle anxiety. All ground connections tend to corrode and develop resistance. Each connection may have to be cleaned. The computer modules resists reactivation and need several operation cycles to relearn and commuicate with each other.
If the air bags have NOT been deployed, the system is responding to a high resistance test result. The seven flashes are the tests being performed. This april fools day. So, I am responding just in case you dont have a calender.

Hello, I have 2005 Tahoe, I replaced Knock sensor's soon after I bought it, as code came up. They will cause ur Milage to drop drastically, I was down to 10mpg ! Bad Knock sensor's can cause engine damage if driven alot & not replace. As for Ground wire's, your Batter Only Has ONE, its the main battery ground! No other wires to follow from your battery! My Break lights stopped working, Replaced Pedal Switch, still no break lights. I haven't found the problem yet, there are many Ground wires under vehicle, if u have Tow Package, check wires there also. I know my info doesn't help much but I wanted to tell you mainly about Battery Ground, no vehicle has numerus grounds from battery ground. Not Factory anyhow!

 

[swathdiver]

Hello, I have 2005 Tahoe...

Welcome to the forum from Florida Popeye!

 

[Moosemoon]

Hello, I have 2005 Tahoe, I replaced Knock sensor's soon after I bought it, as code came up. They will cause ur Milage to drop drastically, I was down to 10mpg ! Bad Knock sensor's can cause engine damage if driven alot & not replace. As for Ground wire's, your Batter Only Has ONE, its the main battery ground! No other wires to follow from your battery! My Break lights stopped working, Replaced Pedal Switch, still no break lights. I haven't found the problem yet, there are many Ground wires under vehicle, if u have Tow Package, check wires there also. I know my info doesn't help much but I wanted to tell you mainly about Battery Ground, no vehicle has numerus grounds from battery ground. Not Factory anyhow!

Thanks for the info.
GM dealer mechanic says the knock sensors are working correctly. Wants to do extensive (read expensive) electrical diagnosis. SOOO I am trying to figure out what I can do to narrow things down a bit.

Right now, for the knock sensors, I’d like to check the PCM connector as there is a pin specifically for that. Not sure where to begin with airbag codes yet.

There are other historical codes that the dealer cannot replicate. I was told the dealer mechanic checked to see if there were obvious problems - but I’m not convinced he did. Worked with Yukon less than an hour. Nice thing is, they didn’t charge me. Guess they figure they’ll make up for it on the backend

 

[MassHoe04]

Can you please clarify if these are active codes with check engine light on and airbag light on. Or are they simply historical codes? You can disregard about 3/4 of the nonsense that has been posted thus far

Was I part of the nonsense? Not intentionally... When I was talking about checking grounds, I may have inter-tangled mention of main battery ground then rambled into mention of checking other ground locations that could cause weird electrical behaviors. Especially grounds for the PCM and BCM being big culprits with a lot of demons people fight on their trucks.

I was suggesting it wouldn't hurt to verify key ground points up in the engine bay and on the body mount by the driver's door.

Apologies if I contributed to any nonsense. No harm intended.

 

[Moosemoon]

Was I part of the nonsense? Not intentionally... When I was talking about checking grounds, I may have inter-tangled mention of main battery ground then rambled into mention of checking other ground locations that could cause weird electrical behaviors. Especially grounds for the PCM and BCM being big culprits with a lot of demons people fight on their trucks.

I was suggesting it wouldn't hurt to verify key ground points up in the engine bay and on the body mount by the driver's door.

Apologies if I contributed to any nonsense. No harm intended.

No harm done. Thanks for your input!

 

[Doubeleive]

Was I part of the nonsense? Not intentionally... When I was talking about checking grounds, I may have inter-tangled mention of main battery ground then rambled into mention of checking other ground locations that could cause weird electrical behaviors. Especially grounds for the PCM and BCM being big culprits with a lot of demons people fight on their trucks.

I was suggesting it wouldn't hurt to verify key ground points up in the engine bay and on the body mount by the driver's door.

Apologies if I contributed to any nonsense. No harm intended.

No, always a good idea to check grounds. the codes particularly srs codes usually aim at a specific problem, like the drivers airbag usually that is a bad connection, the front impact sensor's do go bad from being exposed to the elements, that could tested by swapping said sensor left to right and see if the code follows.
knock sensors are a cross your fingers and hope they work kind of thing it's not uncommon to have to do them twice especially if oem was not used.
brake switch control low voltage could be bad brake switch, poor connection on the light harness or bulb connectors, poor ground on the light harness which is also exposed to the elements
fuel pump module is also exposed and the harness getting corroded is a known issue
personally I would try and address each specific code to rule it in or out and then move on to other possible causes, doesn't seem like these are a bunch of random codes that would be caused by something else

 

[MassHoe04]

No, always a good idea to check grounds. the codes particularly srs codes usually aim at a specific problem, like the drivers airbag usually that is a bad connection, the front impact sensor's do go bad from being exposed to the elements, that could tested by swapping said sensor left to right and see if the code follows.
knock sensors are a cross your fingers and hope they work kind of thing it's not uncommon to have to do them twice especially if oem was not used.
brake switch control low voltage could be bad brake switch, poor connection on the light harness or bulb connectors, poor ground on the light harness which is also exposed to the elements
fuel pump module is also exposed and the harness getting corroded is a known issue
personally I would try and address each specific code to rule it in or out and then move on to other possible causes, doesn't seem like these are a bunch of random codes that would be caused by something else

I had a code my Tech 2 identified as the LF impact sensor. Open circuit, IIRC. Forgot the code number... But anyway, I went right for that on replacement, rather than bother swapping the right side over. Tech 2 was right! It was a bad sensor on left side. I was diagnosed and done in no time.

 

[Moosemoon]

No, always a good idea to check grounds. the codes particularly srs codes usually aim at a specific problem, like the drivers airbag usually that is a bad connection, the front impact sensor's do go bad from being exposed to the elements, that could tested by swapping said sensor left to right and see if the code follows.
knock sensors are a cross your fingers and hope they work kind of thing it's not uncommon to have to do them twice especially if oem was not used.
brake switch control low voltage could be bad brake switch, poor connection on the light harness or bulb connectors, poor ground on the light harness which is also exposed to the elements
fuel pump module is also exposed and the harness getting corroded is a known issue
personally I would try and address each specific code to rule it in or out and then move on to other possible causes, doesn't seem like these are a bunch of random codes that would be caused by something else

Thank you for the input. Since the dealer cannot replicate the fuel transfer pump, fuel level sensor or brake codes (not even as historical) we are choosing to work on the airbag codes and knock sensor codes.
Other than bad gas mileage, the Yukon runs well. The dealer has said the knock sensors are good. O2 sensor also replaced. So think we are done throwing parts at the P0332 code.
Finally have a little sunshine - despite cold north wind. Going out to check ground on battery and the big one at the back of the engine bay.
Next step is to remove fuse box and check all connections to the PCM and their tributaries.
Wish me luck - I need it!

 

[Moosemoon]

I had a code my Tech 2 identified as the LF impact sensor. Open circuit, IIRC. Forgot the code number... But anyway, I went right for that on replacement, rather than bother swapping the right side over. Tech 2 was right! It was a bad sensor on left side. I was diagnosed and done in no time.

Will see what I can find on that sensor. Thanks

 

[Moosemoon]

So far grounds look good. Starting on other tomorrow

 

[MassHoe04]

So far grounds look good. Starting on other tomorrow

Good baseline to start from. At least you won't be chasing all other systems forever, only to find out problems were chassis grounds!

I am sure the expert electrical gurus will get you figured out pretty quickly.