C-5 wont start, no power to anything

[LLC5]

The only thing i disconnected was the star connector for the doors and seats. Im going to jumper the pcm amd bcm together later from the other star connector as dadaroo suggested to see if that sovles the issue

You have both door modules and seat modules unplugged? Plug them back in and see what works. You need your vehicle harness back to OEM for any valid checks.

 

[Pags]

So i jumpered the light green and the dark green wires together but still have the same issue. Everything says no comm except for the IPC now. It says no codes

 

[Pags]

That schematic doesnt quite match the wire colors in my star connector either. Could be i dont know how to read it, i dunno. But reading from left to right the colors are different. But i connected the light&dark green anyway, bcm clicked as if it was on so im assuming that that was the right choice.

 

[Pags]

You have both door modules and seat modules unplugged? Plug them back in and see what works. You need your vehicle harness back to OEM for any valid checks.

Sorry i didnt see your post last night. Ill try that later today

 

[Pags]

So i tested the light green and dark green wires with the ohm meter to see if they were grounding out somewhere. I got infinite on both so i guess we can rule that out. Also, the other night when i jumpered the 2 wires together i forgot i had previosly disconnected the 2 power wires from the fuse box under the hood. So i hooked them back up and tried again but got the same results, no comm, car will crank but not start. But the ignition relay started buzzing when the key is in the "on" position again now that i hooked the 2 power wires back up on the fuse box. So before i go and buy another bcm im going to take the ignition apart again and make sure im getting good connectivity on all the contacts to see if that solves the issue. Also, if i unplugged the current bcm thats in the car, and just plugged it back in do i have to do the whole "handshake" procedure? Or is that just for installing a new bcm?

 

[dadaroo]

No "handshake " is required for removing and reinstalling the same PCM or BCM.

 

[Pags]

Im going to recheck all the grounds again, along with the tumbler lock resistance 1 more time, as well as take the bcm apart to check for any obvious issues before i blow the money on a refurbished one. Hate seeing the car just sit in the garage

 

[dadaroo]

Forget the VATs resistance. If that was an issue the car would not crank.

Here are the grounds info we discussed so you can check the ignition relay circuit.


Ground locations - Corvette Forum


Here is a post on crank and no start you can review. Mainly at this point I want you to focus on post 30 to check the fuse voltages associated with the ignition electrical switch.

We'll talk again after you do those checks or if you have questions earlier.


1998 cranks but no spark - Page 2 - Corvette Forum

 

[Pags]

IT LIVES!!!! took all the grounds off, cleaned them again, took bcm out and blew it out with air, prayed for a little, turned the key and heard the sweet sound of 701 rwhp again!! Im gonna take it out for a ride, crossing my fingers that i get it home this time without a tow truck lol

 

[Pags]

Just did the whole no comm on me again! I drove to advance auto to return some crap, tried to leave and got the whole no comm again. Disconnected the battery, re connected it and its fine again. While i was here i borrowed their scanner and no codes came up. So maybe bad battery connection? Gonna pray a little more and try to make it home

 

[Pags]

Nope, made it about a half mile. This time i got no comm to pcm, bcm had 1 code, U1255, which is serial data line corruption or something like that, so i took it off, and jumpered the pcm and bcm, still says no comm. Put the serial buss back on, pcm says no comm, bcm says U1255 again. Every other module has comm now, no codes.

 

[Pags]

So im thinking this is more of a pcm issue now

 

[Pags]

So aftet just pissing with the if ignition turning it on, off, over and over it just started again and was able to make it home tow truck free

 

[Pags]

So from what happened yesterday, im thinking the problem has to be the pcm, the wiring from the pcm to bcm, or my sub/sound system is draining the battery while i drive causing my issues bc of low voltage.

 

[dadaroo]

As far as I can tell you still have not measured the voltages at the fuses that the ignition switch serves. I provided the fuse numbers above. Especially since you said you exercised it and got the car to run.


I doubt the PCM is bringing the whole system down. A bad BCM might do that.

 

[Pags]

Well after doing everything I could in my garage and not being able to narrow it down to a for sure cause, I got it towed to the corvette shop. Turns out it's the pcm causing the issues. Go figure it's the most expensive thing to fix. So she's gonna be parked for a while until I get the money and time to put in a 2002 pcm for more reliability, and flexibility when it comes to tunes. And to top that off, the tow company hooked up to the wrong spot when they towed it so the entire front end is crooked. So I currently have a claim in the works for that as well.

 

[LLC5]

So aftet just pissing with the if ignition turning it on, off, over and over it just started again and was able to make it home tow truck free

That sounds like a bad electrical portion of the ignition switch, not a PCM. Did you tell this scenario to the shop doing the diagnosis?

 

[Pags]

Yea, it even happened to them while they were diagnosing it. They got it to run for a bit by replacing the ignition relay, then It wouldn't start on them after turning it on/off a few times. They said they isolated each component with their computer scanner and the pcm was the only thing giving them no comm still.They said that they didn't pull the wheel well and check the wires that go to the pcm though. So I'm gonna get it towed back to my place so I and check all the pcm wiring and probably change the entire ignition with a new one just to be safe.

 

[Pags]

Well.... The tow truck company hooked the Vette up by the bumper gaurds, not the manufacturer tow hooks to pull it up on the flatbed. So she's back in the garage for a completely different reason now,and looks like it may be a total loss to the insurance company.. wonderful.

 

[dadaroo]

Sorry for your situation. Hope it all works out well. There are plenty of C5s out there.