I have an 05 chassis I put an engine from an 01 truck in with a harness from an 03 Express with the ECU from 03 express. I am rounding the corner on being able to start the engine, but am expecting some possible issues.

I see, with GM trucks in this year range, if you: keep the key on for 11 minutes, off for 30 seconds, on for 11 minutes, off for 30 seconds, on for 11 minutes, off for 30 seconds: the ECU should reset/adapt itself to the new sensors and etc, and then the engine will start.

Is anyone aware of this procedure working for vans, too? I know, the ECU is basically the same, with only some notches that differentiate vans from trucks, but externally is the same. I will try it out tomorrow if I can get it all wired in properly. Otherwise tips without having to buy a scanner to reprogram it are appreciated.

 

I doubt that you will be able to achieve what your looking for.

When resetting an ECU you basically clear the data collected by the computer. The software part which lie in the ROM(Read Only Memory) part stay there unchanged. So if you’re 01 engine has exactly the same spec/equipment as the 03 ECU is programmed for you might be in luck. But I doubt it because the change in generation between the two. We have to keep in mind here the difference between resetting an ECU and reprograming an ECU. This is two different things.

Reprogramming or flashing an ECU is done by the dealer or someone who has the appropriate computer and according to a specific VIN. The exact engine equipment information is sent/downloaded into the ROM part of your ECU. In other words, the software is tailored to your specific vehicle. It is programmed to take in charge a specific list of sensors and other electronic equipment specifications. From there the ECU collect data into the RAM or volatile memory of the ECU while you are driving. As matter of fact, it is where your trouble code is stored.

The ignition key sequence you referring to is a procedure to clear the data in the RAM. It does not reset the ROM or software part.

I guess your shortest path would be to go to the dealer with the VIN of the van where the engine was taken from with your ECU and get it reprogrammed. Again only if a 03 ECU can be flashed for a 01 engine. Unfortunately, I have big doubt.

Good luck

 

Vin from donor truck is long gone.

Wired it all up today, got it to crank, instruments, got oil pressure, and spark, did not hook up any fuel, but assume the GM anti theft disabled the injectors even though there was a fuel smell. (Fuel tank not connected, nor fuel lines)

Due to the variety of sensor tolerances and especially aftermarket, the ECU has to be able to adapt, or like you said, needs to be "Programmed" to accommodate a specific sensor range. I assume, the presence of spark, and instruments, is a good sign. I believe I am unable to fire the engine up in-frame as I cannot bypass the GM theft lock, without an ignition switch tumbler (I am only operating the switch), so it is back to repairing the frame, and getting it ready for the cab. I also do not have the key to the cab, and will have to get one.

 

when you get a new ecu from the dealer its blank....the correction options are programmed to it by the dealer.
your options are:
-find a tuner who can bypass the immobilzer
-have the dealer program the ecu to the new vin and relearn the theft deterrent (if possible. the communication protocols may not be the same). Then do a crankshaft variation learn procedure.