Took a risk on an 07 supercharged donor.... help me get it running?

[AleX1/9]

I found a pretty great deal on an 07 SS supercharged donor after searching for several months on Copart, IAAI, and craigslist far and wide.



Catch is, car was wrecked in the front, and doesn't start with the key. The engine fires off great using a jumper wire on the starter relay pins underhood, but only runs for a few seconds, then shuts off. The fuel pump can be heard, all accessories turn on, and there is no security light on the dash. There is a check engine light and ABS light on the dash, but my OBD reader won't pick them up because the car isn't running.

What I've done so far:

-Checked all fuses with powerprobe, tested relay for starter, all fine.
-reprogrammed the key following instructions found online. Key on 10.5 mins, cycled 3 times with 45 second window. Tried twice, no result.
-Removed and cleaned all connectors on BCM, ECM, and fuse panels and major battery cable/fuse panel connections. Nothing suspect found.
-Disassembled column shrouding and inspected ignition switch connections and transponder ring, looks fine.
-tested clutch switch, ground in one pin at rest, ground on both pins with switch pushed in.

Items that are suspect:

-two sets of wires on the rear speaker shelf that are hacked off, shielded wires and twisted speaker wires tell they go to a factory amplifier/tuner that is missing. All speakers are missing, and there were amp wires strung around. Factory style radio in dash turns on. Not sure if this would affect the starting condition, but I do remember from my car stereo days that this era chevy requires a data wire module for aftermarket installation to provide an actual +12v ignition wire and in some cases door chime and other functions.

-Dash computer shows coolant temp at -40C and low coolant signals. don't think that's it either...

-Driver's side seat belt buckle will not release the belt... again weird but i don't think it's related...

-Unknown sensor found inside vehicle with one broken end (looks like maybe an ABS sensor?) It's about 3 feet long, has dark blue almost silocone like shielding, and small black 2 pin connector on the end. I'll have to post a pic...

My feeling is it has to be something simple like an inertia kill switch or bad key programming. Maybe a factory alarm? I don't have a fob for it. I did all the stupid stuff like add fuel in the tank, install fresh battery with charger, checked engine grounds, ETC...

You guys have any insight?

 

[TheNuker]

I can tell you it should start/run without coolant, Mine was a front end also and all of the coolant leaked out. The low coolant alert is on and the car runs and idles just fine.

If you can post a pic of the unknown sensor I'll check on my 07 ss and see what it attached to.

Nuker-

 

[Adam]

In our experience, if the OBD2 won't read but the instrument panel is coming on, you have an interruption in the data wires that daisy chain through the car.

Are the twisted wires that are on the rear speaker shelf brown and tan? If so, those are data wires. Are you sure they went to an amp or could they possibly have gone up the rear pillar to the roof? Two sets of data wires go to the rearview mirror and if they are severed, you'll have this issue.

It would be safest to try to connect them to wherever they used to connect.

If these were the problem, your OBD2 should work and hopefully the car will start.

 

[AleX1/9]

In our experience, if the OBD2 won't read but the instrument panel is coming on, you have an interruption in the data wires that daisy chain through the car.

Are the twisted wires that are on the rear speaker shelf brown and tan? If so, those are data wires. Are you sure they went to an amp or could they possibly have gone up the rear pillar to the roof? Two data wires go to the rearview mirror and if they are severed, you'll have this issue.

The quickest way to test this is to connect the two wires together but it would be safer to try to connect them to wherever they used to connect.

If these were the problem, your OBD2 should work and hopefully the car will start.

There's actually 2 sets of bare wires and one plug that doesn't have a home:

This is the set I figured went to a factory amplifier (but now know they go to the onstar module)


The other cut ones are a big coax, and two smaller coax cables all three run together up the passenger side rear pillar.



And a plug running to the middle of the rearmost shelf under the window, also likely goes to the onstar module


And the errant sensor? wire i found in the trunk:

 

[Adam]

I can't tell if the twisted wires are brown/tan or yellow. If they are yellow, they are airbag wires. If they are brown and tan, all four go to the rearview mirror.

 

[smithvmi]

And this is where I begin to dread that I cut the rearview mirror wires out with the airbag wires...

if the only wires that would be coming out of the rearview mirror are OnStar wires thank god; my donor was a shitbox LS that definitely didnt have OnStar.

 

[AleX1/9]

Digging into the still unknown loose wiring, there are two distinct groups. This group heads into a black 16 pin plug along with some defroster wires, and then up the pillar and forward underneath the headliner, ran with the sunroof drain. These likely find the wiring going to the onstar mirror or go down the A pillar.

Yel/Blk
lt.grn/blk
grn/whi
brn/whi
grey/shield wire & foil insulation





This next group of wires joins the wires heading down below the 1/4 window and likely through the driver's side kick panel.

Blk/whi
Red/whi
Green
Org/blk + Pnk/blk + shield wire & foil insulation
Gry/blk + Tan twisted pair
Tan/blk + Tan twisted pair

 

[AleX1/9]

I've ruled out amplifier as it seems they placed those under the dash near the clutch. Mine has no sign of pioneer equipment now that I think of it...

 

[smithvmi]

This might be a stupid question but, if the airbag deployed could that add to the issue? Maybe your inertia switch idea wasn't that far off.

 

[Adam]

And this is where I begin to dread that I cut the rearview mirror wires out with the airbag wires...

if the only wires that would be coming out of the rearview mirror are OnStar wires thank god; my donor was a shitbox LS that definitely didnt have OnStar.

The OnStar wires are the ones that would need to be bridged. It's not hard to remedy if they are removed (we accidentally did that on our first car with OnStar). I'll update the wiring instructions to include this step. Sorry about that.

 

[AleX1/9]

Yah looks like the onstar module mounts to the rear decklid between the speakers, and that's what I'm missing. I found this on ebay:



The plugs and wire colors seem to match.

Looking forward to the wiring / bypass instructions!

 

[Adam]

The twisted wires go from place to place throughout the car in a long chain with one end at the ECU and the other end at the OBD2 connector. This means that you can check to see if there is an interruption by checking continuity between the coiled wires at the ECU and at the OBD2 connector. Luckily, we have an SS/SC car here so I was able to get photos of where you would need to check this.

You can test all of this without power going to the electrical system. Connect a voltmeter to one of the OBD2 pins and check both ECU pins for continuity. One of the ECU pins should show to be connected. Test the other OBD2 pin to the ECU. One of the ECU pins should show to be connected. If they don't seem to be connected, go to your twisted wires at the back and temporarily connect the black striped wires together and the tan wires together and retest the OBD2 to ECU connections.

Let us know if this works out for you.

 

[AleX1/9]

Thank you Adam that's gonna make my life much easier!

Unfortunately I'm away from home until Wednesday I'll let you know as soon as get back to it.

 

[AleX1/9]

IT'S ALIVE!!!

All it took was exactly what Adam said, connect the twisted wires back together and BOOM! Motor turned over with the key for the first time since I got it. Topped up the oil and water and let it get up to temp, runs great! It does shake the car pretty bad when running though. I kinda miss having a throttle cable I can work while inspecting the engine bay :/

Not sure if it's a tweaked frame or what, couldn't find any obvious broken mounts or pieces under the car. Did find a REALLY bent driver's side lower control arm though:



The driver's side front corner took the brunt of the impact, so I wasn't surprised about this..... Excuse to buy the ZZP lower control arms???

 

[rallyracer]

IT'S ALIVE!!!

All it took was exactly what Adam said, connect the twisted wires back together and BOOM! Motor turned over with the key for the first time since I got it. Topped up the oil and water and let it get up to temp, runs great! It does shake the car pretty bad when running though. I kinda miss having a throttle cable I can work while inspecting the engine bay :/

Not sure if it's a tweaked frame or what, couldn't find any obvious broken mounts or pieces under the car. Did find a REALLY bent driver's side lower control arm though:



The driver's side front corner took the brunt of the impact, so I wasn't surprised about this..... Excuse to buy the ZZP lower control arms???

Are any of the engine mounts blown out?

 

[AleX1/9]

Are any of the engine mounts blown out?

No I replaced the only one that was broken (front). It could be the bent control arm binding the axle or even pushing into the tranny? I need new control arms anyway so ordered those, and will work on the Konis and hubs while I wait.

 

[Lonny]

Does it shake any time the engine is running or just when you are moving?

 

[AleX1/9]

Does it shake any time the engine is running or just when you are moving?

Really both, worse when driving. The motor runs smoothly, but it vibrates the car like it's on solid motor mounts. Kinda strange... I have to be missing something major like another broken mount.. Time for a second look.

 

[Lonny]

A broken engine mount will not cause the engine to shake but it can allow normal vibrations to amplify into the chassis.

If the engine is shaking I would be looking for something maybe bent or broken that spins while the engine is running.

Temporally remove your serpentine belt and run the engine like you did earlier to see if it's any smoother. This will eliminate the super charger the alternator the idler and the belt itself.

Don't worry about the engine over heating because the water pump is driven internally by a chain.

Also look at the crank pulley while the engine is idling and make sure it is not bent.

A misfire could also be the problem.

 

[SinisterSF]

Silly question but is there coolant in the motor? I have rebuilt a few cars that had broken radiators I didn't notice and didn't realize they were out of coolant until they started to overheat. Point being, when there was no coolant in the system the motor shook like hell, I assume the coolant is figured into the balancing of a motor in it's cradle.