2004 Colorado LS swap with E40 ECM No VIN

[Pulse_GTO]

Helping a friend of mine with his Colorado LS swap. He is using a Current Performance Wiring harness and I helped with the re-pinning that was necessary. The ECM is an E40 out of a 5.3 Trailblazer P/N 12596679 (same number as recommended on their website). Not all sensors are connected to the engine yet, but I wanted to get a head start on modifying the tune file, but when I went to read the current tune, I get a "No VIN detected" message and I'm only able to read the TCM. I tried to poll the car with the Scanner and was not able to. My friend tried his Snap-On scanner and could not connect either. Does anybody have any suggestions?

[gtstorey]

If neither scanner can locate the ECM module, I would suspect a wiring issue. Or an issue with the ECM.

[Pulse_GTO]

Wiring is good, ECM came from a wrecking yard. Would a break in the CANBUS cause any reading errors? Basically if something is not hooked up or plugged in would it cause the ECM to not work?

[gtstorey]

Wiring is good, ECM came from a wrecking yard. Would a break in the CANBUS cause any reading errors? Basically if something is not hooked up or plugged in would it cause the ECM to not work?

That is really what I meant by wiring errors. All of the modules that need to be read must have a continuous path to the DLC. And often the ECM is at the far end from the DLC. Typically the data path is connected within the individual modules so any module removed will have to have the data path "jumped". You should also have a 120ohm resistor at each end of the high speed network, although opinions differ on how important the resistors are.

Here is an explanation on testing the Can Network.
https://resources.aeswave.com/ATG-05...%20may%20occur.

[gtstorey]

And sometimes, but not always, the 120 ohm resistors are located within modules.
You also have to ensure that power is supplied to all required feeds to the ECM. There are often more than one. And maybe multiple grounds.

[edcmat-l1]

Yeah typically everything modern goes through the BCM first, then other modules in a chain. Many 2008ish and up (I do mostly cars, disclaimer LOL) the PCM is at the end of the chain.

Everyone needs a bench harness BTW.

[Alvin]

Helping a friend of mine with his Colorado LS swap. He is using a Current Performance Wiring harness and I helped with the re-pinning that was necessary. The ECM is an E40 out of a 5.3 Trailblazer P/N 12596679 (same number as recommended on their website). Not all sensors are connected to the engine yet, but I wanted to get a head start on modifying the tune file, but when I went to read the current tune, I get a "No VIN detected" message and I'm only able to read the TCM. I tried to poll the car with the Scanner and was not able to. My friend tried his Snap-On scanner and could not connect either. Does anybody have any suggestions?

Did you try writing entire another file or anything? That often corrupts the vin and often the ECM. Especially E40.

If you need another one we sell cores programmed to what VIN you need.