remote start fails on cold mornings

Since the weather has been getting below 15 degrees here, my truck usually wont start in the morning. Seems to only crank for a short period or starts and shuts right off. Later in the day even when its still cold it starts normal. It has gm one touch start so im not sure why it wouldnt fully crank. Its a 04 trailblazer with a compustar one way (cm800?) and a idatalink al-ca. What could cause this? Module flashed wrong? Use of t taps? ( the data wire is soldered at the obd wire)

Sounds like a tach setting to me. You may need to reprogram tach.

Run the vehicle at around 1100 RPM and then program tach.

If you have a CM800-s remote start unit and it is mis-behaving in Tach Mode, why not try switching to Assumed Timed Crank.This option sends a 3 second crank output and assumes the vehicle started.  It is designed for vehicles that have built in anti-grind and use the ECM to control the crank time.  It is option 2-04.  Here is a link to the full install guide for more info : http://techfeed.compustar.com/ft_controllers/manuals/CM800_Full_Install_V1.1_EN.pdfSoldering is fun!

it actually starts, it just shuts off right away. (had to witness it a few more times) it makes me cringe because thats pretty much the worst thing you can do to a cold engine in below zero temps

That is what they do when they lose tach programming.

I will program it, but i never programmed it or hooked up a tach wire because from what i could tell the idatalink handles it via data buss, and it starts fine most the time just not cold mornings

Think I remember a mention from another Forum member that the ADS DL GM1 firmware sometimes drops the Tach

signal.*  If your Tailblazer has "one-touch" starting and it will always start on cold mornings with the key and a quick turnto START and release, I think I would program the CM800-s Feature 2-04 Engine Sensing to Option IV = 3.0 secCrank and let the Trailblazers ECM handle the rest.  The CM800-s will assume the engine started, not monitor theTach signal, and keep the ignition wires powered for the 15 minute run time.  Worth a try.

If you want to stay in Data Tach Mode, you might have to re-program the iDatalink bypass to the Trailblazer again and

then do the Compustar Tach Learn.

* See RacerJames' post in this Pictorial on a Yukon install using an ADS AL-CA w/ DL GM1 firmware.

  https://www.the12volt.com/installbay/forum_posts.asp?tid=133000

Soldering is fun!