Hardest truck you have diagnosed...and fixed

[farmtruc]

We got this truck here and it's probaly one of the top ten trucks we have diagnosed.
No truck is hard to figure out some are just more time consuming and new problems.
Some really test your knowledge and exhaust every idea.

So where do we turn to for questions and ideas for a truck diag like this one.
Nowhere!
We put our minds together and keep on it.
You can tell this one is a bad one.

Btw this by know means is a poke to anyone. Just wanted to share how deep ray and I go into troublehootig trucks.

Back to this truck.

2011 HD sixo and 90e, 2wd
Body and bagged. Lays bumper on asphalt.
I'll post pics later but it's on our facebook page.
Awesome looking truck.

Lots of welding on this truck.
Fuse block and ECM/TCM wiring has been extended.



It took us two weeks on and off to figure this one out. We had other stuff to work on.
It was just a simple No Start issue. Doh.
Well we have found the issues(s) and now it's time to start putting the truck back together after we speak to the owner.
Diag and fixing are two different steps.


Some issues:
No comm
No start
Radio. Cluster not functional
Cluster engine check engine light blinks with key ON
Several fuses blown



This truck comes into your shop.
What's the first step?

[Skylark]

Write down the blown fuses. Replace fuses. Function check circuits. Replace parts as needed. Thank welder for not disconnecting the battery AND grounding the truck prior to welding because he made you $$$!

[farmtruc]

lol, good direction. pretty much what we did, but we ran into a bunch of issues along the way.
One thing we do, we don't care how or how caused the issue, we are just happy we have a challenge and learning more.
definitely a good one to troubleshoot.

CAN communication:
2.5volts idle
Works on differential voltage
3.5volts to 1.5volts

ummm, that wasn't there and boy was that a tough one, lol.

[vortecyota]

Are you gonna tease us? Come on, what all did yall find?

I think all trouble shooters have their own paths they follow. For me, the first steps always include verifying the complaint(s), collecting as much data as possible (what all isn't functioning) and try to determine if all faults share a common denominator or not. That helps me find direction.

Considering the no comm naturally I try to communicate with another module on the bus. If at least one module talks, there's no need to check for 12V on DLC pin 16, gnd or terminating resistors.

Check, replace any blown fuses next and repair any shorts to gnd.

The next quick check I do is check for 5V reference as a quick controller "health check". If 5V isn't present I'll do 1 of 2 things next depending on accessibility. Either check controller feed voltage and gnd V drop OR start disconnecting inputs that use ref V while monitoring ref V to check for s shorted sensor potentially pulling down the reference circuit to gnd. In my experience, nearly all reference circuits are shared externally or internally so any short will disable the whole system. Another sometime quicker method is to de pin the ref circuit(s) at the controller and see if 5V occurs.

In the case of said truck with all the current flowed thru that frame and so many wires cut/ spliced the possibilties are nearly endless.

What all did you guys find?

[vortecyota]

Here's a cool one I did a couple months ago, not difficult but still cool.

A guy I do side work was telling me about his brother in laws Ford truck. Here's what I got: 01 F150 4.6 down for 18 months because it wouldn't pass emissions, rough idle and MIL illuminated. The guy took it to an independent shop, 5 weeks no fix. 8 weeks at a local Ford dealer $700 no fix. After that, he was convinced it wasn't fixable so he thought his only choice was to sell it. No one wanted it so when I heard about it, I knew I had to get my hands on it. The guy supposedly doesn't have much money so I offered to pinpoint the problem(s) at no charge. As soon as I heard the story behind this truck, the Vendetta was born, lol.

I told the guy I have very little time outside of work but if he'd let me keep it for two weeks I'd do my best to diag it for free. He dropped it off in the rain and when I shook his hand as he was leaving I told him I'd let him know what I find in a couple weeks. I was busy so I figured I'd look at it sometime soon... yea f****** right! Lol.

12 minutes later, before he made it home I had found and corrected the issue without buying a single part. I called him immediately and told him to turn around. His mind was blow! Lol bent #4 injector terminal. He drove it all the next day and passed emissions that eve!

[vortecyota]

Here's how I found it so quick. Noticeable misfire, p0304 and p0307. Test ID 53 in Mode 6 indicated a ton of misfire counts on #4 and a small amount on #7. I decided to more or less ignore p0307 but for a base line I grabbed a shot of #7 secondary waveform with my Wyze probe and lab scope. Looked good at idle and during a snap. Moved to #4, looked good at idle but was clearly a lean misfire. The spark line was nearly as high KV as the firing line. Back probed #4 injector control circuit. No waveform.

At first I thought dang the #4 transistor in the pcm is fried (pcm replaced by dealer). Then it dawned on me that the waveform was flat lined when, if no control, should be charge voltage. So I back probed the feed side of the injector and had charge voltage. I thought cool I already whipped this truck, just an open injector coil! Only one last check to do before I call the injector. Disconnect it and check its resistance. Once I disconnected it to check resistance I saw the bent terminal. It wasn't contacting the injector pigtail when plugged up.

$700 and 18 months wasted and all it needed was a terminal bent back with a pocket screwdriver!

It's simply aweful when you don't know it and awfully simple when you do. Lol

This guy will be a customer for life .

[vortecyota]

I talk way too much, lol!

[farmtruc]

I knew you would post up lol. Sounds like we speak the same language. <br />
<br />
Well we found that the comm lines were down. Due to an ebcm module. Trailer module. Tcm module. Bcm. All shorted. <br />
Comm low speed was down due to the radio being shorted. Think soeakers R done for as well. <br />
Something struck this truck or similar. <br />
<br />
We r gonna redo the fuse block and ECM Harness extensions. Very odd the solder is oxidizing and once when we begin assembly we will be faced with opens. <br />
<br />
So far this was the major stuff. <br />
I enjoy it! <br />
No fault really to the owner. This is his tenth truck or so. <br />
Just shit happens. <br />
And as picky as these new trucks are it takes a lot to be patient. <br />
If we didn't do this all the time I wouldn't wanna figure it out either. <br />
<br />
<br />
Btw. What is the easiest and simplest way around a shorted tcm in a 6L90e<br />
I Know what the options are just looking for the best approach to replace the shorted tcm.

[farmtruc]

Btw in iphone no idea why br. Breaks are showing lol

[farmtruc]

How many of you have done a 4L80e conversion on a 2010 and up truck?
And the big deal is. Keep all factory functions. Key lock. PRDL.
It's not straight forward due to a few things.