2004 Tahoe (p59) ECM Will Not Take a Tune Unless I Pull Radio Fuse

[connerterry24]

I tuned a 2004 tahoe, cam swapped with a converter. very simple setup. I tried to flash a base tune, and it would not take the tune. It would time out halfway through the write. The truck wouldnt do anything. I thought the battery went out halfway through the write (which would not have made sense because i had a battery tender hooked up to it). I figured the battery just had a bad cell and assumed the worst. I then pulled the amp and radio fuse out, and it worked like a dream. Why is this required on some 99-06/07 classic trucks but not on others. I tune on my 2000 sierra all the time without pulling the radio fuse, but this tahoe would not even think about taking a tune with the radio fuse in. What's the reasoning for this? Does the radio draw too much power while trying to flash a tune?

[blindsquirrel]

https://forum.hptuners.com/showthrea...ead-this-first

You didn't read the sticky threads, did you?

[connerterry24]

Just curious why some require the fuse to be pulled whereas some do not.

[TheMechanic]

Just curious why some require the fuse to be pulled whereas some do not.

It is an issue with the serial data stream that is used for programming and communication between modules. Different things need to know haw fast they are going while others need inputs for cluster etc. If one of these modules is "awake" and attempts a stay alive message it will bump the programming and fail to write the tune.

[2xLS1]

It should only be 03-07 classic trucks with RAP. It is part of the stock radio. Aftermarket radios that use an external chime adapter, some work ok some are shit. It should never be required on 99-02 trucks. They newer HPT hardware seems to have more trouble with them than the older MPVI1s.

[blindsquirrel]

All the other modules are supposed to go offline when the PCM tells them it's getting reprogrammed. If it's an aftermarket radio, it probably isn't fully compliant with the class2 messages like the OEM radio was. Lots of shortcuts on things like that in aftermarket electronics.

[connerterry24]

Thanks for the replies. That makes sense because mine is a 2000 and i had no issues but the 2004 did have issues. It makes you wonder how someone discovered the solution to that issue. must have taken forever to figure that out.

[blindsquirrel]

Aftermarket garbage doohickeys cause comms issues even for dealership guys. Not a secret by any means.

[TheMechanic]

If I am not off boarding on those.
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