Car model and year: 2017 Corvette Z06 A8
Symptom:
Came from Copart with a front hit. Radiators, crash bar, steering rack, abs module, front cradle, and a few suspension components are the main areas of damage.
What I did and discovered:
I can put a wrench on the crank and it turns and can feel it come upon compression.
That being said I got battery all charged up and wanted to see if the car would turn over on its own. It will not. Let screen start up and when you press in brake pedal and hit start the main display goes dark except the engine light. All other interior lights remain on. After a few seconds the main screen comes back on. Hooked it up to scan tool and cleared all codes we could, however the scan tool will not connect to the ECM. All fuses are good checked them twice.
Suggestion:
If your steering module is damaged, it won't complete the DATA circuit to the ECM to allow the engine to start. I believe the EBCM will do the same. If there is any module disconnected or damaged, I believe it will need to be sorted out first.
Question: only choice is to purchase new as used ones will be Locked to their old respective cars. Am I interpreting this correctly?
Actually, no, new or used you will need an SAE J2534 pass thru device and a subscription to SPS to program the modules to your VIN.
I know it's expensive, but I would recommend this: MongoosePro® GM 2
Symptom:
Came from Copart with a front hit. Radiators, crash bar, steering rack, abs module, front cradle, and a few suspension components are the main areas of damage.
What I did and discovered:
I can put a wrench on the crank and it turns and can feel it come upon compression.
That being said I got battery all charged up and wanted to see if the car would turn over on its own. It will not. Let screen start up and when you press in brake pedal and hit start the main display goes dark except the engine light. All other interior lights remain on. After a few seconds the main screen comes back on. Hooked it up to scan tool and cleared all codes we could, however the scan tool will not connect to the ECM. All fuses are good checked them twice.
Suggestion:
If your steering module is damaged, it won't complete the DATA circuit to the ECM to allow the engine to start. I believe the EBCM will do the same. If there is any module disconnected or damaged, I believe it will need to be sorted out first.
Question: only choice is to purchase new as used ones will be Locked to their old respective cars. Am I interpreting this correctly?
Actually, no, new or used you will need an SAE J2534 pass thru device and a subscription to SPS to program the modules to your VIN.
I know it's expensive, but I would recommend this: MongoosePro® GM 2
This is what you should expect a professional to use: GM MDI 2
Good to know:
As for the data circuit not being completed it depends on the amount of damage done to the harness and connectors. The EBCM and Power Steering Modules can be removed from the circuit and the engine will still start. Note the Data Communication Circuit in the following picture:
The connectors that connect to the EBCM and the Power Steering Module pass the signal through the connector to the next module in the circuit. If the connector is trashed and the connection through the connector is broken then you will need to repair or replace the connector or maybe the harness.
One other thing can keep the engine from starting is the system is killed after a collision. If the battery still had some charge in it when you got the car and it wasn't disconnected and reconnected the engine won't start. Have had to disconnect/reconnect the battery to get several C7s that were wrecked at the track started so we could drive them home or get them on a trailer.
Little update:
I repaired the loom and checked for continuity in several locations, all appears to be okay. So far I got a used ABS module and plugged it in. It is recognized in GDS2 with a vxdiag nano, I am still waiting on the steering rack. However I am still unable to communicate with the ECM. I have the fenders pulled and there is no damage what so ever that got even close to the ECM. I know some have said that the rack can be removed and the ECM will still work, but I am hoping that it is actually not the case and once I get the steering module plugged in the ECM will wake up. If not I am leaning towards a completely new wiring harness which doesn't look like much fun to swap out, and if that doesn't work the possibility of a fried ECM.
Finally succeed:
Success!!
I was able to get the car to crank over under its own power today.
I am still without a steering rack. So after identifying that only one terminator on the CAN was currently present I started probing the CAN wires at the steering connector. I was able to find where the CAN came in and determined that it is only sent back out if it is connected to the module. It does not pass through the connector alone. I made some quick jumpers and essentially bypassed the steering rack.
I hooked up the battery and like magic when I turned on the "key" I had fuel level registering on the dash. Hooked up gds2 and verified I could now talk to the ECM. Pulled the ignition fuses and hit the button and she turned over! Might not seem like a big deal but after 3 full days this is a major win as far as I'm concerned. Additionally she didn't make any god awful sounds so at least I know there isn't anything catastrophically wrong with engine. Now I can somewhat comfortably move forward with replacing the cradle, get front end back together and start tracing down the Christmas tree of lights and codes I have.
www.uobdii.com
Good to know:
As for the data circuit not being completed it depends on the amount of damage done to the harness and connectors. The EBCM and Power Steering Modules can be removed from the circuit and the engine will still start. Note the Data Communication Circuit in the following picture:
The connectors that connect to the EBCM and the Power Steering Module pass the signal through the connector to the next module in the circuit. If the connector is trashed and the connection through the connector is broken then you will need to repair or replace the connector or maybe the harness.
One other thing can keep the engine from starting is the system is killed after a collision. If the battery still had some charge in it when you got the car and it wasn't disconnected and reconnected the engine won't start. Have had to disconnect/reconnect the battery to get several C7s that were wrecked at the track started so we could drive them home or get them on a trailer.
Little update:
I repaired the loom and checked for continuity in several locations, all appears to be okay. So far I got a used ABS module and plugged it in. It is recognized in GDS2 with a vxdiag nano, I am still waiting on the steering rack. However I am still unable to communicate with the ECM. I have the fenders pulled and there is no damage what so ever that got even close to the ECM. I know some have said that the rack can be removed and the ECM will still work, but I am hoping that it is actually not the case and once I get the steering module plugged in the ECM will wake up. If not I am leaning towards a completely new wiring harness which doesn't look like much fun to swap out, and if that doesn't work the possibility of a fried ECM.
Finally succeed:
Success!!
I was able to get the car to crank over under its own power today.
I am still without a steering rack. So after identifying that only one terminator on the CAN was currently present I started probing the CAN wires at the steering connector. I was able to find where the CAN came in and determined that it is only sent back out if it is connected to the module. It does not pass through the connector alone. I made some quick jumpers and essentially bypassed the steering rack.
I hooked up the battery and like magic when I turned on the "key" I had fuel level registering on the dash. Hooked up gds2 and verified I could now talk to the ECM. Pulled the ignition fuses and hit the button and she turned over! Might not seem like a big deal but after 3 full days this is a major win as far as I'm concerned. Additionally she didn't make any god awful sounds so at least I know there isn't anything catastrophically wrong with engine. Now I can somewhat comfortably move forward with replacing the cradle, get front end back together and start tracing down the Christmas tree of lights and codes I have.
www.uobdii.com
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