i am doing a 2002 trailblazer this weekend >> i have heard horror stories about this truck and this is my first one. I am an 11 year veteran installer but i have yet to do this car..... if there is anyone who can clarify the following for me I would appreciate it:
1. is it true that if the facotry head unit is unplugged I will get errors?
2. is it true that the head uit acts as a suppliment to the ECU
3. is it true that there are fiber-optics in this car making an aftermarket install difficult?
4. should I turn this car away? (please be honest)
just so you know.... my customer wants me to keep the factory head unit. thr plan is for me to change the factory door speakers and add a dual bandpass box that I will be building. I'll be using 2 sony explod amps and coax in the doors....the subs are kenwood.
I am figuring on using 2 line level (hi to low converters) to give me the low level outs off the head unit..... then split the rear out for the rear speakers and sub giving me a total of 6 preouts. 1 amp is a 4 channel the other is a 2 channel.
is this do-able?
please let me know
thanks in advance
dave
The head unit is on a Class2 data bus and it comunicates with the OnStar module. Its the SUV's that have the factory amplifier that you need to be concerned about. The amplifier is controlled by data from the headunit. If the headunit is removed then the amplifier will not turn on so you can't input any audio signal into it and OnStar can't be used. Thats why the radio has to be relocated. Also there is only two channels of fixed audio going to the amplifier, so the amplifier does the balancing and fading.
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Karl
Pacific Accessory Corporation
Mobile Audio Interfacing Equipment
Connecting You to Your Music Since 1976
i also heard though that there is issue with gains off the head unit.... what I mean is that if I was to use the hi to low converters, I would have a hard time getting volume from the head unit..... any ideas on this? by the way... i dont think there is a factory amp on this head unit.... but from what I have gathered so far many functions such as door locks and onstar still flow through the head unit. am I correct to assume this?
Since you don't have a factory amp, you can get enought signal from a LOC since you are tapping off of speaker level and not line level. Only OnStar audio is connected to the headunit. The doorlocks share the same data bus as the radio, as well as OnStar, SRS, ABS, BCM, windows, HVAC, instrument cluster, etc., but the radio has nothing to do with those components.
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Karl
Pacific Accessory Corporation
Mobile Audio Interfacing Equipment
Connecting You to Your Music Since 1976