2007 chevy trailblazer remote start

Thanks!!  I was figuring it would be a smaller wire, but itnever hurts to ask!!  And I know the IGN would be DC...my problem was making sure that if I probed the wrong wire in AC mode, that it wouldn't hurt anything!!!  Thanks for the info!!

OK...well, gotta try this again!!!  Everything went great!!  Got the GM-SL2 hooked in with the RS-660, everything worked perfectly...EXCEPT the dang tach stuff.  I got down in the wire loom and found 4 white wires.  1 was a 14ga. ignition wire and there was 3 small, 18/20ga wires...all went to the connector where the ignition/battery wires went into....separate sockets though.  But I checked all 3 smaller wires and none of them would do anything on AC voltage.  I did have it running and nothing on them.  Is there somewhere else it might be or maybe another color??  I thought about just going straight to the injector and trying that, but ran out of time today. 

This is a base model Trailblazer, nothing special other than being a total electric, seats and all.  Any help is greatly appreciated!!  Thanks again all!!!

I'll try that one next, Thanks.  I assume it's on the end by the Tach??  Thanks again.

There is only one white wire in the plug at the cluster on the saab/trailblazer/rainer/envoy

it is the tach, but since you are new why not hook your meter up to it jsut so you can see what it look like and hove the level changes whn the mototrs rpm change

Has it been really cold- like 5 or 10 degF below?   Believe me- The Trailblazer will wait to activate the alternator- to ease engine load on cold start-up-   I first thought the owner's had bad alternators- until I read about it on the Trailblazer Forum- Below is the excerpt I read- It was related to people wondering why their voltage gages did not show proper voltages on cold starts......and the electrical devices speeding up after a while.....I have three people tell me this happened to them- starts- then stops all three tries- Once I go back to tach sensing- all is fine..........I will try to find something about it in the service manual......

Just heard thru the grape-vine that the voltage jump after a (very) cold startup is perfectly normal for the GMT360 chassis. Apparently, the PCM takes the alternator 'off-line' for 10-30sec to lessen the load on an extremely cold engine. This explains the ~10 to 14.4VDC jump you see on the dash gauge and see/hear from the dash lights and heater blower. Basically, you run on battery power alone for a few seconds after a stone cold startup.

Here is what I have found so far from the Trailblazer service manual:

When high current loads (blower, rear defogger, headlamps, cooling fan, heated seats, power seats, electric "AIR" pump, or power windows) are operating or cycled "ON", the generator's voltage regulator can delay the rise in output. This effect, usually at lower engine speeds, can take up to ten seconds to ramp up the generator output. This is done to avoid loading the engine severely. To increase current (amperage) output, additional torque is consumed by the generator. The engine computer (PCM) will ramp up engine/generator speed in small steps so engine speed variations are not noticeable to the driver.