GM300 Ignition Sense line

RadioSouth · Post by **RadioSouth** » Sun Feb 08, 2004 2:41 pm

When one hooks up ignition sense thru the 16 pin connector for the 1st time does the internal fuse automatically blow or do you need to remove
the fuse for ignition sense to work ?

thgiz · Post by **thgiz** » Sun Feb 08, 2004 3:12 pm

They will blow on their own. But I usually like to cut it. That way if you ever want to reverse the process a drop of solder is all you need.

RadioSouth · Post by **RadioSouth** » Sun Feb 08, 2004 5:20 pm

Thanks!

jackhackett · Post by **jackhackett** » Sun Feb 08, 2004 6:46 pm

Don't count on it to blow by itself. If you have the main power and ignition hooked up with the fuse still in there, the radio will pass voltage back through the ignition lead when the key is off, but there won't always be enough current through the fuse to blow it. I've seen that done, and the guy's wondering why the car radio stays on when he turns off the ignition.

MO_TRASHER · Post by **MO_TRASHER** » Tue Feb 10, 2004 10:33 am

Here's a little trick I've used. Hookup only the negative lead on the main power wire harness and turn on the key. The radio will power up. Key the mic. The fuse will blow and the radio will shut off. Hook up the main power harness. Turn on the key. The radio will power up.
This is NOT recommended if someone has replaced the fuse with plain wire!!

RadioSouth · Post by **RadioSouth** » Tue Feb 10, 2004 4:03 pm

Thanks for the tips Jack and Bob !

Sundown · Post by **Sundown** » Thu Feb 12, 2004 5:04 am

Dumb question...

CDM doesn't have the same fuse thing, right? ignition sense works differently for CDMs?

MO_TRASHER · Post by **MO_TRASHER** » Thu Feb 12, 2004 8:04 am

Sundown wrote:Dumb question...

CDM doesn't have the same fuse thing, right? ignition sense works differently for CDMs?

There are no dumb questions. Since the lords at /\/\ don't provide a real schematic for the CDM series, (at least I've never gotten one, just some general service book) it's hard to say.
There is a provision in software to have the radio work with or with out the ignition sense line.
Don't know the details, I'm on a different computer.

Sundown · Post by **Sundown** » Thu Feb 12, 2004 8:41 am

ok, and the GM300 doesn't have any such software option I assume?

kyfireman143 · Post by **kyfireman143** » Sat Dec 09, 2006 5:41 pm

well i'll be darned! that little trick works like a peach! my gm300 in my POV was already setup like this to require the ignition sense wire, which is what i wanted. my buddy saw my install and wanted the same for his truck. so we ran the wire, connected to an ignition switched fused connection on the block, and it still came on with or without the ignition sense connection. hooked it up just as suggested, keyed the mic, worked immediately. reconnected everything, came on with the ignition! thanks a million. saved us a lot of time finding the fuse and clipping it!

Post by **HumHead** » Sat Dec 09, 2006 5:46 pm

MO_TRASHER wrote:
Sundown wrote:Dumb question...

CDM doesn't have the same fuse thing, right? ignition sense works differently for CDMs?
There are no dumb questions. Since the lords at /\/\ don't provide a real schematic for the CDM series, (at least I've never gotten one, just some general service book) it's hard to say.
There is a provision in software to have the radio work with or with out the ignition sense line.
Don't know the details, I'm on a different computer.

The CDMs are set up for ignition sense through the CPS option under Radio Configuration.

They do not have the ignition sense fuse. I'm not sure exactly what would happen if you try the TX with the B+ lead disconnected trick with them, but I would bet that it will be either nothing or an expensive repair.

ve3nsv · Post by **ve3nsv** » Sun Dec 10, 2006 7:09 am

HumHead wrote:
MO_TRASHER wrote:
Sundown wrote:Dumb question...

CDM doesn't have the same fuse thing, right? ignition sense works differently for CDMs?
There are no dumb questions. Since the lords at /\/\ don't provide a real schematic for the CDM series, (at least I've never gotten one, just some general service book) it's hard to say.
There is a provision in software to have the radio work with or with out the ignition sense line.
Don't know the details, I'm on a different computer.
The CDMs are set up for ignition sense through the CPS option under Radio Configuration.

They do not have the ignition sense fuse. I'm not sure exactly what would happen if you try the TX with the B+ lead disconnected trick with them, but I would bet that it will be either nothing or an expensive repair.

With power to pin 10 but none to the main power connector the CDM series radios won't even power up so no worries there. One of the issues with the CDM's is if the supply voltage and voltage to the ignition sense pin isn't the same it won't always power up.

RFguy · Post by **RFguy** » Sun Dec 10, 2006 11:02 am

Since the lords at /\/\ don't provide a real schematic for the CDM series

Yes they do. Order the detailed service manual. I can find the number if required.