Engine not turning over and no OBD Comms to ECU after engine changeover - please help

[madmarlon]

Hi,

Done a search for this fault on forum and can't find exact same problem, so hopefully someone can help.
My LFX motor seized in my VF 2014 V6 Auto UTE so decided to swap out engine as easiest path to fix.

Donor motor from wrecker had wiring loom and sensors with it.

Left original ECU in car. Left original transmission in car.

Tried to start after changeover and relays clicked but no turn over. Fuel showing super low and loads of service messages come up.
Tried to connect my Thinkcar OBD Scanner but it won't communicate with ECU. It talks to BCM and any other modules that don't require presence of ECU.

I thought perhaps ECU was shot and so I replaced it from donor car (I know that security will need removing to work but I thought I might get OBD COMM's going)
I still have no COMM's and still have same fault.

I did not swap original sensors over. If they are canbus sensors could this be the issue if they had VINs registered?? If so which ones do I swap over.

Any help will be appreciated, as it's doing my head in.

Thanks

Marlon

 

[stooge]

left the original looms in car?

the sensors on the motor are not vin locked, if you left the wrecker loom on the engine i would be starting with removing that because they treat looms like sh!t at wreckers.

does it look/smell like they hit the motor with a cleaner/water?

the idiots have a tendency to make the motors look clean while forcing water into all of the plugs with a pressure sprayer and then the engine sits there for weeks and corrosion sets in so you would need to go over the whole thing looking for dodgy connections.

if all your engine did was seize than i would expect everything in your engine bay to work apart from the engine, keep your original ecu in, trace all wiring to make sure nothing is damaged/squashed, check all earth points and clean this is important as one bad earth point can cause all sorts of issues.

 

[madmarlon]

Loom looks good from inspection but maybe I'll pull loom of original engine just to eliminate.

I tested battery and ignition supply and the earth at the pins on the blue plug and all are correct.

Does anyone have a wiring diagram to show how the CANBUS is connected up as I'm guessing that is the connection that is broke.

I did try following cabling and looks to go from blue plug to next plug down but not sure from then on. I'm guessing the connection back to BCM must be via the large plug up by the fuse box.

 

[vywgn]

Swap the loom back with the 1 from your car

 

[lout]

popping ze fuze
no power to ecu

 

[Fu Manchu]

Always swap your old sensors and loom over. Always.

 

[madmarlon]

Thanks for all the pointers and I've managed to fix it.

So I managed to get hold of the databus schematics which allowed me to trace the canbus system.

Going from the OBD port I knew that I had COMMs to BCM and electronic brake module.

Looking at the diagram I could see that the steering module was next inline and I couldn't see that module.

Checked the plugs on the steering module and all looked fine and were even clicked in, but looking closely at the pins, I could see a couple that had bent over side wards and so were not connecting. Straightened back up and tested and hey presto, I could now see all the modules and the ECU at the end. All works properly now.

Would not have found this without manuals from this forum to see what the COMMs order was so thanks to the uploaders.

 

[Fu Manchu]

Thanks for all the pointers and I've managed to fix it.

So I managed to get hold of the databus schematics which allowed me to trace the canbus system.

Going from the OBD port I knew that I had COMMs to BCM and electronic brake module.

Looking at the diagram I could see that the steering module was next inline and I couldn't see that module.

Checked the plugs on the steering module and all looked fine and were even clicked in, but looking closely at the pins, I could see a couple that had bent over side wards and so were not connecting. Straightened back up and tested and hey presto, I could now see all the modules and the ECU at the end. All works properly now.

Would not have found this without manuals from this forum to see what the COMMs order was so thanks to the uploaders.

View attachment 244714

The second best bit is when you shared the solution with us. Too many people never post the outcomes once they have used the Commodore enthusiast brains trust, and that is poor form.

PS. Keep your old harness and all your old sensors. Clean them. Bag them in labelled zip locks. Mark all the engine harness ends with tape with their relative attachment written on it. Future you will thank you.