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View Full Version : Gm ls2 hot rod crate motor and harness with there ecu question about checksums


AllOutPerformance
September 22nd, 2011, 05:49 AM
I pulled the file out of this car (68 camaro with gm crate ls2) and it had a bunch of checksums out of range and prompted me saying it cant be reflashed in this condition.Has anyone seen this?whats the way around it.Thanks
ringram
September 22nd, 2011, 08:16 AM
Yeah just press the button to fix the checksums, it will be fine, you can then save and flash away. Ive done it a few times.
AllOutPerformance
September 22nd, 2011, 08:24 AM
Thought so just making sure awesome man thanks for help
GMPX
September 22nd, 2011, 10:58 AM
I am not sure why they disabled the checksums in those ECM's, we have also seen it on some production cars too, must have been a finalised calibration on a Friday afternoon.
Now there is a difference between 'Checksum Error' and 'Checksum Disabled'.
If the Checksum is disabled then you are pretty safe to correct them and flash the file in. If the checksums are actually wrong then don't correct them and flash it in, chances are there was something wrong with the read.
AllOutPerformance
September 22nd, 2011, 12:25 PM
They were disabled turned on flashed and all good.another Wierd thing is you can't change the fan settings.Owell tune came out nice picked up 50whp over the stock file that was in it.
AllOutPerformance
September 29th, 2011, 09:33 AM
Ok question.The gm harness has no ac ref,so when the ac gets turned on it doesnt bump the idle speed up.Looks to use a e67 computer 2006 ctsv computer layout,any idea if i can pin into the ecu connector to signal the ecu the ac is on to bump idle speed?and what pin would i use?
AllOutPerformance
September 29th, 2011, 09:34 AM
would it be pin17 on c3?tq requested?
AllOutPerformance
September 29th, 2011, 09:36 AM
or pin 57 on c3 ac pressure signal
joecar
September 29th, 2011, 01:45 PM
My understanding is the ECM uses the AC Pressure Signal, it checks that the pressure rises above some threshold value.
gmh308
September 30th, 2011, 04:23 PM
Ok question.The gm harness has no ac ref,so when the ac gets turned on it doesnt bump the idle speed up.Looks to use a e67 computer 2006 ctsv computer layout,any idea if i can pin into the ecu connector to signal the ecu the ac is on to bump idle speed?and what pin would i use?

The AC is controlled via a signal on the CAN. The ECM gets this signal, turns on the AC and and then adjusts the engine torque and speed in line with AC load and cycling.