04 Chevy Suburban databus/bypass

Ya'll,

A friend and I are installing a Crimestopper remote start + alarm in his 2004 Chevy Suburban (has Passlock II, theoretically). The databus interface / Passlock bypass device we are using is the Crimestopper GM-U7. We've got the whole thing wired up, triple-checked EVERYTHING, and no dice.

When we go to program the GM-U7, we follow the instructions (push button down, install wiring harness, turn key to ON position, wait for blinking light, release button), but the light never blinks to acknowledge we turned the key to the ON position. It's like the GM-U7 doesn't know the car is on. Of course, it should be getting this information from the connection to pin 2 of the OBD-II port, right? We're 99.9% sure we've got everything connected right - there's only a handful of connections to be made to the GM-U7.

We're at a loss - does anyone have any experience with the GM-U7, especially with 03 or 04 Chevy trucks?

Thanks VERY much!

-Dave Dixon
dave@scoutmasterdave.com

Make sure that you have a good connection on your ignition input wire (pink from truck).  Also, I beleive that the tach wire must be connected as well as any switches (such as valet, or remote start override switches) in order for the programming to initiate.  It doesnt sound like a problem with the bypass unit...if it were, the truck would still turn over.  it would just run for a moment and then stall.  (and the security light on the dash would come on)  to make sure this is the case, put the key in the ignition and try to remote start it. 

Thanks for your reply! We are positive we have good connections to the ignition wire. The tach wire is connected (non-pink color from a fuel injector), and all the switches, etc. are connected.

Programming the alarm works fine - it's the programming of the GM-U7 interface/bypass unit that doesn't work. I failed to mention in my original post that the door lock/unlock and door triggers don't work, either - that's what leads me to believe there is a problem with the GM-U7. It seems to me that as soon as we can get that thing to recognize what car it's installed in, everything will start working.

Any other ideas? :)

the bypass is probally bad also you need to install diodes on the lock\unlock wires as the bypass will act funny if it sees a positive on the lock wires use the supplied diodes and put the stripe toward the alarm this may fix the problem you can try tech  tommorrow at 8009986880

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tj

use diodes on the door lock wires to make sure that only neg gets to the bypass this may fix the prob

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tj

iv seen it before with automobility bypass's that some work on 2003 truck, , and some work on 2003 and 2004, , , there was a data difference between the 2 years, , so they made an updated moduel that will do both 2003 and 2004 years.     Maybe that is your case, , there may be an updated version of that bypass and you got old stock?  its a possibility.   I had those exact same problems.

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2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

Disconnect the module for atleast two minutes. Disconnect all but the battery and ground wire into the module. Confirm with a digital meter that you have 12 volts across these wires. Plug in the module then connect the data wire from the module to the purple data wire at the truck's diagnostic connector under the dash. Then try to program the module. You stated the correct programming sequence. If it fails to respond then replace the module. After the module is programmed, then hook up the lock/unlock wires and negative out when running wire. Don't bother with any other wires.

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sparky

what is the GM-u7?  if its anything like an 04 tahoe... (  )  then you need DEI 456G for the data bus and 555L for the passlock 2.  make sure you have the right passlock wires.  its not ORANGE / black for the ground... take off the steering wheel cover and grab the passlock wires right at the harness.  should be yellow (R) and black (ground).

also, since 99 on those trucks, its best to go to a chasis ground low in the drivers kick.  the trucks tend to have a high resistance (4ohm + )  anywere else, and that can interfere with learning the tach.  the tach should be any non-pink wire, i used purple, at any coil and test around .5 volts ac. up to 1.0 volts ac.

also test for a factory alarm.  the disarm module is on the underside of the drivers door switch panel, take off the whole door card.  its a light green wire that tests (-) with the key cyl.

thats about all i recall from that truck, i did a viper 160xv the other morning in an 04 tahoe.  should be the same thing.

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MECP certified installer