Circuit relays on head unit

[Keith]

Ok, I am not sure about the plausability of this question. I have been told by installers that it is not possible to do without having schematics of the electrical system; which I am not sure they would have been able to read anyways.

A while back I installed an XM radio for my 2000 LS. The problem I have is that the integration to the head unit is not all the best. The antenna signal is fine using the FM Modulator, however the installer said it is not possible to make it so that the XM radio unit is powered on when the car is started. Every time I want to use the XM radio, I have to manually turn on the radio and when I turn off the car, the XM radio turns off, but the stereo stays on and goes to static until the door is opened.

I am under the impression that there is a power lead going to the head unit that is on until the door is opened. I would also assume that the power lead going back to the factory AMP, would be on this same power lead or atleast the same relay.

Is it possible to tap in to this power source to power the XM radio off of this lead?

Has anyone done anything similar?

--Keith

 

[joegr]

RE: Circuit relays on head unit

What you ask should be possible. I know that there is such a signal on the 2004's and 2006's. It is actually an output from the radio that then drives the power windows, amplifiers, and so on. (The radio has an input from the door switch, so it knows when the door opens.)
The signal you need is called "Delayed ACC Power." It is pin 2 of the Navigation head unit on the 24 pin connector. This applies to the 2006. I think that there are major electrical differences between the 2003+ and the 2002- cars though. I suggest that you get a voltmeter and look at voltages at the connector pins with the key off, but radio still playing. Then look at them again after opening the door. The one that switches should be the one you want.

Otherwise, order the wiring diagrams for your car from Helm.

 

[Frankie X]

RE: Circuit relays on head unit

OK, OBDII subject # 2.

The radio has 3 power sources:
1. Constant power for KAM (Keep Alive Memory) station presets, internal clock, and menu presets.
2. Power during Crank used a power-up trigger.
3. The important one-- Acessory delay power relays controlled by the FEM (Front Electronic Module), which recieves signals for this function from the DDM(Driver's Door Module) and the HIC (Hybrid Instrument Cluster).

Whiteoak sublets our aftermarket stereo and alarm installations, and our guys have a workaround for this.

Wait.

I'll find out and get back to you, but I need to know what you have in your dash. Factory stereo? Navigation? Premium/Audiophile option?

 

[Frankie X]

RE: Circuit relays on head unit

There is no 100% workaround.

The accessory delay is signalled into the audio unit through the famous multiplexed network wires. These should never be cut or tampered with.

You'll get most of what you need if you tap your XM directly to the power feeds into your audio unit.

Here goes:

There's 3 connectors at the back of your radio. One has 8 pins, one has 20 pins, and one has 16 pins. That's the only one you want to look at.
Find a Yellow w/Green stripe wire. That's hot in run/accessory. Use it for anything on your XM needing "Run", "Switched", or "Key" power.
Find an Orange w/Black stripe wire. That's hot at all times. Use it for any type of constant power the XM needs.
Ground the XM wherever convenient; there's no shortage of grounded dash braces behind the radio.

There's so many different types of satellite radios out there you're on your own regarding the connections at the XM.

Keith, you probably already know how to remove your radio, but if not, it's easy:

Remove the center dash vent unit with a screwdriver. It just pops out; it's held in with clips.
Take out the ashtray, then pop off the fake wood bezel around it. Unplug the seat heater switches.
Now you'll see two 7mm head screws above the radio and two more below the heater control. Undo them, and the radio and heater head come out as a single unit (they can be separated).
You shouldn't need to unplug all connectors and actually remove the radio. Just tip it forward and get at the 16 pin connector.

Depending upon the type of XM you have, it still might not recognise accessory delay and will still turn off before the radio does.

Let's hope for the best!