2001 Suburban stalling issue

[Fless]

Might be worthwhile to ohm the battery negative post to various points on the block.

EDIT: @kbuskill I also wonder if it would change much under load (cranking). Also re-check the underbody grounds that were fixed earlier. On mine one of the holes was a bit stripped so I added a washer and a nut with a through bolt.

 

[kbuskill]

Small update...

Went to my buddies this evening with the Tech 2. When I got there his battery was low, to the point of not starting the truck, so we hooked jumper cables up to my Burb and got his started.

I hooked up the Tech 2 and started looking through the menus. I could look at and communicate with all of the modules except the Driver Information Center and the HVAC module. Both of those would tell me there was no communication. Kinda weird.

Anyway the BCM had DTCs in the history for loss of communication. We let the truck run for probably 30-45 minutes before it finally shut off on it's own.

Once that happened, and the fuel gauge was reading empty as usual, the Tech 2 couldn't communicate with the Engine Control Module.

I also used a meter to test the ohms from the negative battery terminal to the alternator bracket.

I first tested the ohms on my Suburban to get a base line reading between the negative terminal and the alternator bracket... 0 ohms.

Now my truck has huge 2/0 battery cables that I built so I'm not sure if or how much that affects my reading but I digress.

When we measured the same points on his Suburban it measured out over 200 ohms... so I'm still leaning towards a faulty/dirty ground or internally corroded cables.

I tested between my negative terminal and the ground stud on the firewall and it read between 50-75 ohms.

On his truck, same locations measured over 200 ohms again.

He is going to remove and replace the battery cables and clean the ground locations tomorrow.

I am thinking the ECM is dropping it's ground and causing this issue.

I guess we shall see... I will keep you all posted as this saga progresses.

Thanks for all the recommendations so far.

 

[PG01]

Small update...

Went to my buddies this evening with the Tech 2. When I got there his battery was low, to the point of not starting the truck, so we hooked jumper cables up to my Burb and got his started.

I hooked up the Tech 2 and started looking through the menus. I could look at and communicate with all of the modules except the Driver Information Center and the HVAC module. Both of those would tell me there was no communication. Kinda weird.

Anyway the BCM had DTCs in the history for loss of communication. We let the truck run for probably 30-45 minutes before it finally shut off on it's own.

Once that happened, and the fuel gauge was reading empty as usual, the Tech 2 couldn't communicate with the Engine Control Module.

I also used a meter to test the ohms from the negative battery terminal to the alternator bracket.

I first tested the ohms on my Suburban to get a base line reading between the negative terminal and the alternator bracket... 0 ohms.

Now my truck has huge 2/0 battery cables that I built so I'm not sure if or how much that affects my reading but I digress.

When we measured the same points on his Suburban it measured out over 200 ohms... so I'm still leaning towards a faulty/dirty ground or internally corroded cables.

I tested between my negative terminal and the ground stud on the firewall and it read between 50-75 ohms.

On his truck, same locations measured over 200 ohms again.

He is going to remove and replace the battery cables and clean the ground locations tomorrow.

I am thinking the ECM is dropping it's ground and causing this issue.

I guess we shall see... I will keep you all posted as this saga progresses.

Thanks for all the recommendations so far.

Grounds, grounds, grounds.....people don’t believe me when I tell them. I know you know this Ken... I’m just saying

 

[kbuskill]

Grounds, grounds, grounds.....people don’t believe me when I tell them. I know you know this Ken... I’m just saying

Same here... people look at me like I have three heads, and clearly I only have two, when I tell them about grounds.

I think they probably think, to themselves, it couldn't be something so simple causing such big issues.

My grandfather was an electrician in the US Navy for 20 years and he taught me everything I know, he just didn't teach me everything he knew... lol. But he used to tell me about bad/dirty grounds causing issues and I have seen it first hand.

 

[Fless]

Same here... people look at me like I have three heads, and clearly I only have two, when I tell them about grounds.

I think they probably think, to themselves, it couldn't be something so simple causing such big issues.

My grandfather was an electrician in the US Navy for 20 years and he taught me everything I know, he just didn't teach me everything he knew... lol. But he used to tell me about bad/dirty grounds causing issues and I have seen it first hand.

People don't understand that grounds are half of the circuit. Like climbing a mountain: when you're at the top, you're only halfway done.

 

[kbuskill]

Well after thoroughly checking all the grounds and 12V power supplies at the ECM connectors and checking the data line circuits individually by removing the comb at SP205 and bringing the modules online 1 at a time and checking for continuity between the ECM's serial data lines and SP205...

I finally broke down and condemned the ECM as bad.

We procured a used ECM from a 2002 Escalade and I reprogrammed it using my Tech 2 and TIS2000. Installed it and relearned the Passlock.

It appears to run better than ever. I guess only time will tell but I am about 99% positive that it is fixed this time.

Will keep you posted.

 

[wjburken]

Well after thoroughly checking all the grounds and 12V power supplies at the ECM connectors and checking the data line circuits individually by removing the comb at SP205 and bringing the modules online 1 at a time and checking for continuity between the ECM's serial data lines and SP205...

I finally broke down and condemned the ECM as bad.

We procured a used ECM from a 2002 Escalade and I reprogrammed it using my Tech 2 and TIS2000. Installed it and relearned the Passlock.

It appears to run better than ever. I guess only time will tell but I am about 99% positive that it is fixed this time.

Will keep you posted.

 

[kbuskill]

View attachment 263667

Holy cow, how did you get a picture of me?... lol

But seriously, I sure hope so.

 

[wjburken]

Holy cow, how did you get a picture of me?

 

[exp500]

Planning, persistance, logic, pretty hard to beat! Good work.