What did you do to your NNBS GMT900 Tahoe/Yukon Today?

[swathdiver]

are you sure?., I found that be the other way around I couldn't get the thing to stay on unless it was plugged into the bottom of the tech2, but I don't recall if I have had to do anything that required the candi to be powered during a restart. Even when programming via acdelco-tds (connected to the computer/internet ) I just had it plugged into the bottom of the tech2

No, I might have that backwards! Can't remember.

I've had one of those Mornsun power supplies in my Wishlist for years, they've doubled in price now to just over $30. Guess I ought to buy one just in case mine goes out.

 

[Doubeleive]

No, I might have that backwards! Can't remember.

I've had one of those Mornsun power supplies in my Wishlist for years, they've doubled in price now to just over $30. Guess I ought to buy one just in case mine goes out.

it's a lot of work to replace that thing, more than I wanted to tackle

 

[swathdiver]

it's a lot of work to replace that thing, more than I wanted to tackle

I remember seeing a write up somewhere on how to do it once. I have the tools should it ever become necessary, just not sure if I still have the eyes for it!

 

[Doubeleive]

I remember seeing a write up somewhere on how to do it once. I have the tools should it ever become necessary, just not sure if I still have the eyes for it!

more work than I want to do just for something I can plug into the wall instead, lol

 

[swathdiver]

more work than I want to do just for something I can plug into the wall instead, lol

That's the one! I really appreciate that guy's videos.

 

[Charlie207]

I do not have mine memorized but it should be under body and at some point it should ask you if you have option jl4 or not (built in brake controller)
are you trying to cycle the abs pump or look at abs speed data?

I'm trying to figure out why I have the ABS, TCS, BRAKE lights on my dash.

Both front wheel speed sensors are tight... I triple-checked harness connections this morning.

I want to see if the ABS controller is sensing the left & right sensors, but that particular function isn't working in the Tech2. This leads me to think there might be a grounding issue with the module. I'm trying to find a professional/official diagram and list of grounds that would affect the ABS module. The fuse is good. I pulled/swapped the 25A fuse with other good ones, and nothing happens.

When I get a multimeter in my hands I'll be able to test each wheel speed sensor for continuity, to rule that out.

Could another reason be a damaged wire or harness from the front diff actuator? (spitballing) I think the oil pan of the 6.0 banged that area when installing it.

 

[j91z28d1]

I'm trying to figure out why I have the ABS, TCS, BRAKE lights on my dash.

Both front wheel speed sensors are tight... I triple-checked harness connections this morning.

I want to see if the ABS controller is sensing the left & right sensors, but that particular function isn't working in the Tech2. This leads me to think there might be a grounding issue with the module. I'm trying to find a professional/official diagram and list of grounds that would affect the ABS module. The fuse is good. I pulled/swapped the 25A fuse with other good ones, and nothing happens.

When I get a multimeter in my hands I'll be able to test each wheel speed sensor for continuity, to rule that out.

Could another reason be a damaged wire or harness from the front diff actuator? (spitballing) I think the oil pan of the 6.0 banged that area when installing it.

I don't believe a sensor input missing is going to keep the tech 2 from accessing the abs module. that's either power, ground or can bus lines to it.

I feel like it should also had the ecm throwing a code that it has lost communication, but that might just be my system. since there's over 30 modules in mine, there's a request check engine light code they can send the ecm to turn on the dash light when something major happens to them. your abs sounds major.

I wouldn't be able to look up a trouble tree till Thursday, but without a code to start with. it's basically going to be checking for power at the module. shorts to power and ground type of thing.

 

[Fless]

But I also had a bent serial port pin on the Tech2, so I had to fix that.

This is exactly one of the reasons why I left that big fat cable connected to my Tech 2; I didn't feel like connecting/disconnecting it every time would be good for the connection. That and for convenience, having the cable ready to plug in to the truck.

 

[Doubeleive]

I'm trying to figure out why I have the ABS, TCS, BRAKE lights on my dash.

Both front wheel speed sensors are tight... I triple-checked harness connections this morning.

I want to see if the ABS controller is sensing the left & right sensors, but that particular function isn't working in the Tech2. This leads me to think there might be a grounding issue with the module. I'm trying to find a professional/official diagram and list of grounds that would affect the ABS module. The fuse is good. I pulled/swapped the 25A fuse with other good ones, and nothing happens.

When I get a multimeter in my hands I'll be able to test each wheel speed sensor for continuity, to rule that out.

Could another reason be a damaged wire or harness from the front diff actuator? (spitballing) I think the oil pan of the 6.0 banged that area when installing it.

The codes should give you a pretty good idea of what is wrong

 

[Charlie207]

The codes should give you a pretty good idea of what is wrong

I want to ignore codes at this point, and focus on grounds. The ABS system is offline, and I need to ensure that it's working first.

 

[Doubeleive]

Well.... Then you will probably have to get under there with a meter and start testing for power ground, ohms. You will probably need a diagram to reference and values expected for each pin

 

[Charlie207]

For the grounds.... How many are there for the engine bay?

One at the back of the driver's-side cylinder head.

One on the bottom of the block, behind the PS pump.

One on the front of the passenger's side cylinder head.

Anywhere else?

 

[j91z28d1]

if the abs module is under the truck around the drivers seat area on normal ones, there's a ground hidden down there for it somewhere too

 

[Charlie207]

While digging around for loose wires and other dumb stuff I ripped out the smoked front diff. and slammed in the replacement.

I drained the old fluid from the replacement before bench-pressing it up into position - every ounce counts - and was happy to see that it was fairly clean & no sparkles in sight.

Filled it up with synthetic Lucas fluid. I'll throw in the front CVs some other time. I need a beer.

I'll see if anyone wants to buy the bad one as a core for a rebuild. Does $50-75 seem like a fair price to ask?

 

[Charlie207]

Plugged the AutoCal V3 in to pull the codes:

 

[j91z28d1]

I feel like you might need a month description to all data for this one. that's a lot of stuff

 

[j91z28d1]

wired in a toggle switch inline with my hood adjar switch so I can tell the ecm the hood is open when it's not without setting a fault code.


seemed to work on the first test drive.

 

[kbuskill]

wired in a toggle switch inline with my hood adjar switch so I can tell the ecm the hood is open when it's not without setting a fault code.


seemed to work on the first test drive.

Ok, I will take the bait... why?

 

[Doubeleive]

View attachment 436147Plugged the AutoCal V3 in to pull the codes:
View attachment 436148

 

[Charlie207]

Looks like (after a cursory glance) all the U-codes are related to modules not talking.

I love how there were were zero issues before the motor swap..... Such is life.