I was under the suv and found this 13mm bolt. It looks like a ground cable that broke off. It is on the inside frame on driver side. Any idea where it terminate? Wonder if this can cause my problem.

 

Sorry, I can't help with this as I'm not familiar with the topic but good photos and description of the problem. Hopefully someone that knows will respond???

Good Luck!

 

That is a major ground and known to make funny things happen. I can look under my truck tomorrow.

 

That'll be great if you can do that. Thank you! Maybe it's grounded to the engine block? From my understanding after tracing the negative cable from the battery. The negative cable ground from battery to engine block and a smaller maybe 12 Gauge wire ground to the front chassis on the front right side. There is a strap that grounds the firewall to the rear engine block.


* The new PCM came in, I did the swap and the relearn key procedure. For some reason, I do not see my immobilizer light coming on. The SUV didn't start, but I continued with the procedure. After waiting 10 minutes, turned ignition to off, wait 5 seconds, turn ignition to ON, and NOTHING. At that point, I was worried. So I sat there for couple minutes browsing online regarding relearn instructions and I was just stumped as to why NO immobilizer light. Well, I tried to start SUV again and it turned over. The communication problems I have is still there, but at least now the scantool is reading the correct VIN number.

 

I disconnected the battery and measure the resistance (ohm) across pin 6 and pin 14 and I get a reading of 120 ohms. From my limited understanding, that reading should be 60 ohms since there are two terminating resistors in parallel. Where do I go from there?

 

Wow, I stumble upon this youtube video after so many hours of watching videos on grounds.

. This chevy this guy is diagnosing with communication problem is similar to mine. I will continue probably follow this lead.

 

Sorry it's taken so long but it's been a crazy week. I can take pics but it won't be till tomorrow

 

Reconnect the ground wire that's broken and that may clear up all of your issues. Make sure the metal to metal contact is "shiny" when connecting the ground.

ChiefM and EricVonHA...You guys are good. Thanks for helping him out. Hopefully that's what this site is all about!

RS

 

Reconnect the ground wire that's broken and that may clear up all of your issues. Make sure the metal to metal contact is "shiny" when connecting the ground.

 

Except I'm not sure where it attach to though.

 

Here is the schematic for the HS buss. See if you can figure out where a bad connection would be to cause loss of communication with the modules listed above.
And yes, the resistance between 6 and 14 of the ALDL should be 60 ohms.
A quick study makes me think the problem.is in the left IP junction block.
And, I don't think your vehicle has the controller called out as BCM (Auxiliary)

 

Short in the left IP junction block? Can I jump the connection to test? Or pull junction block and test for continuity between certain pin? Also the diagram show a 120 ohm DLC resistor after EBCM and also after ESCM? I thought only two resistor, one internal to ECM and one after ESCM in this vehicle.

 

The XXX or -XXX is referring to an option in the vehicle. The 3 letters are the RPO codes of different options. If your vehicle has that option you follow the XXX lines. If you vehicle doesn't have that option You follow the -XXX lines.
In your example UE1 refers to "Communication System - Vehicle, G.P.S. 1"
You need to find the RPO code label in your vehicle. Then you can use that to determine which branchs of the schematic to follow.

As far as the open circuit goes.
If the buss is disconnected, as yours seems to be, the modules can't talk across the break but they can talk where they are still connected. The system acts like two seperate busses.
Thqt means that they can still function somewhat but not perfectly. Things are also designed to be robust enough the maintain some functionality even when broken.

 

Thank you for the explanation! I can read the flowchart now.

 

Can you also explain the 9 line crossing the two wire?

 

That line denotes the two wires are a "Twisted Pair" when you find them in the harness you will see they have been twisted together. This is used in many low level signal wires to help with noise reduction. The also use this in unamplified audio signals and microphone signals for the same reason. If you need to replace any great length of CAN bus wires you should use twisted pair. I just put two wires in a drill chuck, put the other end in a vise and run the drill to twist them together.

 

First, find the RPO code sticker in your vehicle and verify if UE1 is listed on it.
Also do the same check you did for pin 6 of the ALDL for pin 14.
The VCIM is located in the center of the IP behind the HVAC control module. It has 3 connectors on it. X1 is white X2 is listed as natural, probably tan. X3 is gray.

 

No rpo code unfortunately. Someone took the liberty and removed all labels from the suv. But good news is that I found the vcim and it is NOT plugged in. So that explains everything. Thank you for your help!

 

Did that solve all your problems?

 

Yes. I didn't have time this morning to reconnect everything so I wasn't able to test. It did solved the problem. No more lights on the dash. I had to remove the brake control module connection and reconnect it for it to work. Probably going to zip tie some of the connection so they're tight. Now onto the next problem. The transmission is not wanting to move forward. I don't have first gear. It's able to move in 2nd gear by either using a scantool to command it into 2nd or by removing the trans fuse. Any ideas? Should I start a new discussion?

 

Start a new discussion. I'm not a trasn guy so not a lot of help from me.

 

Sorry I didnt post the pics, I was in the hospital for a few days. Glad you got it fixed!!

 

1

Sorry to hear.. hopefully all is well with you...

 

I'm good now and thanks!
Blood pressure shot up really high, they did a hundred tests and still have no idea why.

 

Hey Man, glad you’re ok. Tech II says [emoji3] check for adverse interactions or possible side effects of any Rx you’re taking.

I was given given an Rx to control hypertension. 5 Mo later I felt weak and just not right. We have xlnt Ins so got checked out at ER. Docs kept telling me their equipment was not working. Turns out my potassium level was so low only the expensive lab equipment could verify I was ready to stroke out or start convulsing. It took two days of IV’s and potassium tablets to get back to normal and last two days in hospital had symptoms like DT’s without the benefits of being a drinker.

My doc told me to make a f/u Appt with him. I f’d up and did not. That almost killed or crippled me. If you can, run labs Mo’ly until you determine what’s up.

Merry Christmas [emoji320] and hope all is on the up and up.


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I use to take meds for a while for panic attacks, don't know why I started to get them but it was a fact of life for a while. More than likely it was the prolonged stress of military life and deployments. I took them for years and then the doctor got me off of them when I retired. It's been almost 7 years since I took any and everything had been fine. I started back on a low dose just to get my body back to normal. Feeling much better and back on track.

 

Great, my family thanks you for your service and dedication.


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