2013 Escalade ESV no comms ECM, TCM

[skpyle]

Hello All,

I don’t know what I have done, but I have screwed something up on my 2013 Escalade ESV.
There are no communications with the ECM or TCM.

Back story: I am disassembling the L94 6.2L to determine what is tapping. Heads and timing cover are coming off.

Removed various items from front of engine. Disconnected wiring harness from intake and such.

I removed fuse #21 FSCM 25A from the underhood fuse box so the fuel pump would not run while I had the fuel rail supply line disconnected.

Disconnected the battery (-) cable from ground stud on the front of the passenger’s cylinder head to remove the harness ground wire ring terminal.

Reconnected the battery (-) cable to the cylinder head.
I was keeping the battery connected to be able to open the lift gate. My intent was to store removed parts in the back of the Escalade.

When I was done for the evening, I tried to open the lift gate. Nothing. Key fob, handle button at the liftgate, rocker switch in the headliner, nothing worked.

I also noticed the DIC in the instrument cluster was displaying a raft of messages.
Most relating to alternator and engine harness disconnected.

I did notice there was no vehicle speed indication, just three dashes.

I connected my Tech 2 and started digging.


I found the lift gate control module, found no active DTC’s for it. Looking in Data, I could see the ‘LGM front control switch’ and ‘LGM Disable’ go from INACTIVE to ACTIVE when I moved the rocker switch.

I kept digging.

I went to the Body Control Module: It was present, and had a DTC.
DTC was B1517 Symptom 07 Battery Voltage Above Threshold
I don’t know if this is a result of the alternator being disconnected or not.

I then looked at the Body Control Module (aux: it had No Comm.

A bit lost now, I started looking at various other modules:


EBCM had 2 DTC’s:

U0101 Symptom 00 Lost Communication With TCM

U0100 Symptom 00 Lost Communication With ECM/PCM A

 

[skpyle]

I looked at the ESC, found 1 DTC:
U0100 Symptom 00 Lost Communication With Engine Control Module <ECM>

I looked at the ECM, found No Comm.

Same for TCM, No Comm.

 

[skpyle]

At this point, I tried to fall back on the basics. I started checking for blown fuses in the underhood fuse box.
With the key on, all the fuses I thought relevant to this had power on both sides:

#4 ENG (15A)
#5 ECM/THROT CONT (15A)
#12 ECM BATT (10A)
#14 TCM BATT (15A)
#19 TRANS IGN 1 (15A)
#56 ECM IGN (15A)

I have inspected the engine/intake wiring harness, and have found no obvious damage.

I have tried googling this, and not really gotten anywhere.

I have AllDataDIY, and didn’t find any thing for ECM/TCM comms.

 

[skpyle]

And, I am not the sharpest crayon in the box.
In the googling, I saw references to DTCs U0100 and U0101.
I didn’t know where to look for them.

Idiot

Those were the DTCs in the EBCM and ESC.


I will look in AllDataDIY for those DTCs and go from there.

 

[Geotrash]

My next step would be to reconnect everything to where they belong, leaving the negative battery cable until the very end. But before you put the negative battery cable back on the battery post, pull the positive cable off the battery and touch the positive and negative battery cables together for a second. Then reinstall the positive cable on its battery post, followed by the negative cable on its battery post. The process of touching the cables together when there is no power entering it from the battery will eliminate any residual charges in the components that can cause weirdness like what you're seeing.

 

[kbuskill]

Did you unhook the harness from the ECM when you removed the intake/heads?

 

[mikez71]

There is an accessory wakeup signal, goes from accessory position of ignition switch to BCM, which apparently wakes up other modules, but passes through BCM to power the ECM and TCM wakeup circuit.

not saying this is your problem, and I don't see how that circuit would get zapped..
So hoping a reset like geotrash recommended might solve it.

 

[skpyle]

My next step would be to reconnect everything to where they belong, leaving the negative battery cable until the very end. But before you put the negative battery cable back on the battery post, pull the positive cable off the battery and touch the positive and negative battery cables together for a second. Then reinstall the positive cable on its battery post, followed by the negative cable on its battery post. The process of touching the cables together when there is no power entering it from the battery will eliminate any residual charges in the components that can cause weirdness like what you're seeing.

Will do. I will set the intake loosely back on the engine and reconnect all plugs that I disconnected.

Will let you know what happens.
Thanks!

Did you unhook the harness from the ECM when you removed the intake/heads?

I did not. I only disconnected the plugs necessary to remove the intake manifold. I do not have the heads off yet.
Thanks!

There is an accessory wakeup signal, goes from accessory position of ignition switch to BCM, which apparently wakes up other modules, but passes through BCM to power the ECM and TCM wakeup circuit.

not saying this is your problem, and I don't see how that circuit would get zapped..
So hoping a reset like geotrash recommended might solve it.

View attachment 468157View attachment 468158

Good to know, thank you!!!




I appreciate all the advice.
I am still troubleshooting this issue, but also still actively working to get the heads and timing cover removed.

 

[skpyle]

Found it. #5 cylinder intake non-AFM lifter roller is fragged.

I have not gotten a look at the cam lobe yet, but I am assuming it is ruined.

Will post full update later.

Full DOD delete is now beginning.

 

[skpyle]

And I just realized that I posted in the wrong post…

 

[skpyle]

I have not gotten back to this as I have been engulfed in disassembling the engine.

What started as a tapping turned into a DOD full delete, possibly a rebuild.

I will get back to ECM/TCM after the engine is back together.

 

[hagar]

Did you have the key on when you were hooking and unhooking the battery?

 

[fredcook]

What condition is your battery in? Most every time I've experienced a rash of lost com, no com, mixed with random other DTC's, it was a weak battery. Since you're dissembling the vehicle, I assume it's not charging the battery. Make sure it's charged and run tests with a tender on it. The only other issue (happened once) I've seen that causes this was a bad ground.

 

[skpyle]

Did you have the key on when you were hooking and unhooking the battery?

No sir. I only turned the key back on after I reconnected the battery (-) cable to the cylinder head.

What condition is your battery in? Most every time I've experienced a rash of lost com, no com, mixed with random other DTC's, it was a weak battery. Since you're dissembling the vehicle, I assume it's not charging the battery. Make sure it's charged and run tests with a tender on it. The only other issue (happened once) I've seen that causes this was a bad ground.

I replaced the battery at the end of January this year. At each oil change, it tests good at around 12.65VDC after sitting overnight. Once I removed the alternator, I kept the onboard battery tender plugged in. I guesstimate battery voltage was around 12.6VDC when I was having ECM problems.

Ground points and cable terminals at cylinder head and left strut mount are clean and tight.



Thanks!