My setup is as follows:
- Remote mounted radio in the trunk
- Radio head (Model III) mounted in center console
- Motorola remote-mount kit including external speaker (mounted under passenger seat)
- Relay to convert ground signal on Pin 8 to 12v+ (stereo mute on the police package requires +12v to activate)
- Car battery is in trunk
The relay is 4 terminal SPST. As wired, it gets power from pin 14 on 2 of the terminals (one to provide + for the switch and one to provide +12v which is fed up a wire to the center console). Ground is supposed to come from Pin 8. When PTT, what should happen is the switch is closed and the power from pin 14 flows thru to the radio mute. But that is not what happens. I only get about 2-3 volts. Note that the installation manual for the radio even advises getting the 2 power and 1 ground connections from the radio, so from what I can tell this is as-intended by Moto.
I have tested the stereo mute function manually by applying 12V from one of the accessories under the center console and it works as it should. I've also tried running 12V from the radio in the trunk to the stereo mute wire under the center console (off pin 14, constant on 12V when radio is on), and this also works (but of course it mutes the stereo constantly when the MCS 2000 is on).
I have tested all the posts on the relay with a voltmeter using various configurations to verify ground or power at each terminal that should have it, and it all seems to work correctly. So, I don't believe the problem is with the relay (I've also swapped out the relay just in case). When I manually try and trip the relay by applying power and ground directly from the battery, it correctly flips the switch inside the relay, so I am sure it's not the problem.
I ran some other voltage tests with a voltmeter. Results here (all tested with voltmeter):
> 1. Neg lead on voltmeter to battery - terminal; Pos lead to relay output (supposed to provide +12v); result is +24-29 volts when PTT
> 2. Neg lead to battery - ; Pos lead to Pin 14 on radio; Result is +12.5 volts with radio turned on and NOT pressing PTT
> 3. Same as #2 except when pressing PTT, the voltmeter fluctuates between 25-45 volts! (what the heck!?)
> 4. Neg lead on voltmeter to Pin 8; Positive lead on voltmeter to Pin 14; Result is 7.9-8 volts with radio in standby; jumps to 27 volts when PTT
I can't figure out why the "sum of the parts" doesn't work, but each individual section seems to work. It's as if something is not kosher when PTT. The install manual says that pin 8 is supposed to go to ground when PTT, but whatever it is doing, the setup is not passing +12v no matter what I've tried.
Based on my testing, I have to wonder if there is something wrong with the ground connection on Pin 8. That seems like it's the problem, but I don't know why or if this whole scenario is normal. I know the stereo mute function in the car works (confirmed/tested), the relay works (also confirmed/tested), the wiring is good (confirmed/tested; note I have also checked for ground fault on the wire from trunk to center console and could not detect any), pin 14 outputs +12.5v or more (higher when car is running). Pin 8 seems to be the oddball.
I have searched this board (and others) but have not found this same situation described. I did find one other post on BatLabs where someone indicated MCS 2000 "AA" radios cannot have the accessory pins programmed. This particular radio has a "AA" in the middle of the serial number. However, I presumed that post meant the programmable pins, which in my case I am not using.
I've checked for all the "DOH" mistakes such as wiring the pins on the acc plug incorrectly, but all seems good. I have even tried a new accessory plug, but it's no help.
The radio IS programmed for radio mute. Also, power to the radio +12v is directly from the battery stud (not the terminal... instructions from Dodge on the PD package say not to do this and Dodge provides a tap about 1 foot from the battery which feeds directly off the pos terminal). Negative is run directly to the ground stud next to the battery, which is the closest ground to the radio (and again following Dodge protocol).
My thoughts atm:
- Is it possible programming is not fully setup for radio mute? If it needs to be set in more than one place, perhaps the programmer missed a spot?
- Could it be something to do with the Charger's electrical system? I have to admit that is my only complaint about this car with the PD package. It seems to have some odd behavior at times with regard to the electronics. I'm wondering if this radio problem could be related to how the radio is grounded and/or receiving power versus how the PD connector in the passenger compartment is grounded/powered.
- is there something wrong with Pin 8 on this radio?
- Should I just stop tinkering with car electronics (i.e am I being a moron here somehow?)
Any thoughts will be greatly appreciated! Thanks.
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