L83 K5 swap problems

[devlmaycry81]

Okay, I've got an l83/6l80e supposedly from a 2016 Silverado in a 1988 in a K5 blazer. It ran when purchased, then when I went to clean up the rat's nest/fire trap on day one and like an idiot didn't disconnect the battery and direct shorted a 12v cable. Hasn't started since.

Corrective actions were I pulled out the janky OEM mess that was crammed in the truck. Swapped in a stand-alone harness. Ensured I had 12v to all my factory lines that should. Hooked up any loose engine grounds I could find. Took my time straightening things out while I waited on the new harness. Followed the directions on the new harness and it seems to have the OBDII port wired correctly. I've got 12v to the port, ground, and the canbus lines are there.

Now, whenever I hood my pro cable up I get a "detect protocol error." Connects fine to my wifes car. I suspected maybe the ECM was toast, and ordered a new one, didn't think about it being blank and needing programmed at the dealer, but it gets the same error. Is that an expected error, or should it still be able to connect and detect it?

All of my other prior experience was with gen III motors. I know the gen V is a significant change from those. A quick google shows noise on the system and resync interface.

Anyone else run into similar issues and have any troubleshooting tips?

[cadillactech]

Okay, I've got an l83/6l80e supposedly from a 2016 Silverado in a 1988 in a K5 blazer. It ran when purchased, then when I went to clean up the rat's nest/fire trap on day one and like an idiot didn't disconnect the battery and direct shorted a 12v cable. Hasn't started since.

Corrective actions were I pulled out the janky OEM mess that was crammed in the truck. Swapped in a stand-alone harness. Ensured I had 12v to all my factory lines that should. Hooked up any loose engine grounds I could find. Took my time straightening things out while I waited on the new harness. Followed the directions on the new harness and it seems to have the OBDII port wired correctly. I've got 12v to the port, ground, and the canbus lines are there.

Now, whenever I hood my pro cable up I get a "detect protocol error." Connects fine to my wifes car. I suspected maybe the ECM was toast, and ordered a new one, didn't think about it being blank and needing programmed at the dealer, but it gets the same error. Is that an expected error, or should it still be able to connect and detect it?

All of my other prior experience was with gen III motors. I know the gen V is a significant change from those. A quick google shows noise on the system and resync interface.

Anyone else run into similar issues and have any troubleshooting tips?

With your new ECM hooked up and everything connected but key off for 10 mins, what is the resistance measured at DLC pins 6 and 14?

What brand harness?

[devlmaycry81]

Thanks for the reply! Looks like I had 120 ohms at that connection. I have added a 120ohm resistor and am at 60.3 ohms now. Still getting the same error though. Double checked the transmission plug since looks like speartech said that can be an issue.

The brand is highperformanceinjectors. So, generic branding I guess?

[cadillactech]

Looks your CAN bus is properly hooked up and terminated.

Have you checked all powers and grounds to both the ECM and the TCM?

[devlmaycry81]

Turns out it was the ECM wake circuit in the harness. It wasn't energizing so the ECM would never wake up.

Also turns out the harness is pinned for a 3 wire fuel pressure sensor.

Also turns out even with that wired in correctly (the harness has extra wires for multiple builds) I've still got a no start.

It cranks fast, is seeing 73-75 psi at the rail, but either isn't getting fuel or spark. I'll post the tune up later when I have a chance to see if there's anything disabled in it that would cause the situation.

I've also emailed the manufacturer since I've found not only the ECM wake issue but also had the wrong oil pressure connector. So not a good start for a "PnP" harness.

[Shrek]

... Turns out it was the ECM wake circuit in the harness. It wasn't energizing so the ECM would never wake up. ... Also turns out the harness is pinned for a 3 wire fuel pressure sensor. ... Also turns out even with that wired in correctly (the harness has extra wires for multiple builds) I've still got a no start. ... I've also emailed the manufacturer since I've found not only the ECM wake issue but also had the wrong oil pressure connector. So not a good start for a "PnP" harness ...

The old adage that "you get what you pay for" is often very true with respect to aftermarket wiring harnesses.

There are several companies who position themselves as being an "economical" option - another phrase would be "cheap" - which they all too often are.

A company that has thoroughly researched each platform, and that offers platform specific wiring harnesses (rather than your "one size fits all" harness), will have invested more resources into the process - which contributes to a higher retail price (often in conjunction with superior materials).

One aftermarket wiring harness company in particular, seems to have extreme difficulty with quality control - almost like these are manufactured offshore. Sometimes these harnesses are OK - sometimes they are little more than garbage.

[devlmaycry81]

Yep, definitely lesson learned. If I had to guess, I'd say it's attempting to be a copy of a PSI harness. Which I do believe I will be reaching out to so I can replace it with one of theirs.

Right now I've got so many man-hours in this harness I'm over it. Given the state of everything and how the whole clean-up started, I assumed it was something on my end that I'd touched. So far all I've found wrong since installing the harness wasn't caused by me.

The guy the other people have running support for them has been moderately helpful, but there's only so much that can be done remotely on a harness that obviously has something wrong with it. I've no clue if there are any other differences in the harness for the 2018 changes other than the 3-wire fuel pressure sensor. I guess with how I've had to bypass the ECM wake circuit I should make sure it has power when cranking.

I've attached a copy of my tune. Maybe there's something I deleted when I disabled the fuel pump, evap, and FPCM stuff that could be causing the issue. I will also try and get a log this afternoon of it cranking to see if anyone can spot anything. Are there any specific parameters that would be helpful to look at when cranking?

Dudes Tune.hpt

[devlmaycry81]

Pending DTC's:

P0073
P0102
P0113
P018c (deleted in tune)
P0449 (deleted in tune)
P2199
P2227
P2229
U0100

I know some are permanent codes that won't clear until it actually runs, and others might also drop once running. At a glance, none of these look like ones that should cause a no-start situation. Or would they?

[Shrek]

You mentioned perhaps purchasing a PSI wiring harness. PSI is an "economy" wiring harness supplier. Sometimes everything is OK - sometimes it is not.

If you are looking for a USA based Gen 5 wiring harness supplier, the best option is likely Speartech. They have done the most Gen 5 research and development of any USA based company. The next best option might be Howell Engine Development. They make a nice wiring harness, however their ECM / TCM programming is lackluster.

Just my two cents.

DTCs that you listed:
P0073 - AAT Sensor - is the MAF Sensor installed and connected ?
P0102 - MAF Sensor (Low Frequency) - is the MAF Sensor installed and connected ?
P2199 - IAT Sensor - is the MAF Sensor installed and connected ?
P2227 - BARO Sensor - is the MAF Sensor installed and connected ?
P2229 - BARO Sensor - is the MAF Sensor installed and connected ?
U0100 - this likely being set by the TCM - which is reporting that it cannot communicate with the ECM

I never looked at your tune - the above are based on the DTCs that you listed.

[devlmaycry81]

Thanks for the info, I'd not seen much bad about them, but you've a lot more experience on that front than me if just post counts are any indicator. I guess at thing point could be harness, could be something in the tune, could be something I did, but I feel fairly confident that I can run a volt meter. The company and their tech dude worked with me again today. So, given everyone else's lead times I'm going to try and stick it out and figure it out. I just feel frustrated and like I'm behind the 8 ball with genV learning curve.

The MAF is indeed plugged in. It's also matched to the engine and trans as it was the one I pulled directly out of the factory air intake. With the litany of other issues, I've found I hadn't even made it as far as back probing and ranging out the MAF sensor. It's on my to-do list as I investigate more

I can't seem to get the pic of them to attach on my work PC and didn't have time to type up the entire code line. I'm on lunch now so I've time to type them up.

P0073 Pending, current, old, permanent
P0102 Permanent
P0113 Pending, current, old
P018c permanent
P0449 Permanent
P2199 Pending, current, old
P2227 Pending, current, old
P2229 Pending, current, old
U0100 Permanent


When I was scanning during cranking I was showing 73-75 psi at the rail and cranking RPMs. I can connect to the ECM, read, write, and monitor. So I was thinking it was an old code that hasn't dropped off since it's listed as permanent. I feel I was reading that those can stick around after they've resolved for while. I could be totally wrong, and if I am just let me know.

[devlmaycry81]

Well, wiring gremlins aside with the wake circuit and the couple other things. The no start issue issue was related to my 12v keyed dropping to 0v after a second or 2 during cranking. Found another pink wire at the 88 harness that doesn't drop voltage and it cranked up for a few seconds before dieing. So it's progress.

[2stimpy]

I would like to know how you fixed your issue with the wiring.
I have the same harness and also had the wrong wake circuit wiring. I fixed it by swapping the power wires from the ign relay and the wake relay.
Still i got some issues that i cant figure out.
These are the codes I get, and the engine runs verry rich(from the smell of it)
0x7E8: P0113 - Intake Air Temperature Sensor 1 Circuit High (Permanent)
0x7E8: P1682 - Driver 5 Line 2 (Permanent)
0x7E8: P2138 - Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation (Permanent)
0x7E8: P2228 - Barometric Pressure (BARO) Sensor Circuit Low Voltage (Permanent)
I checked if the throttle, map and (multi)maf sensors are wired correct. And they do.

I personally thing P1682 is doing the damage but I have no clue how to find the problem.