Installed UHF, now radio is slower to turn off?

[TheOoz]

I put a UHF in last weekend, and now when I turn the key off (XJ) the radio seems to have power for a few seconds more than it used to.

If I unplug the UHF wiring (power) the radio returns to the standard "almost" instant power down when the key is turned to off.

I don't think I have a problem, just thought it was an odd result as it seems like the UHF is storing power and the radio is using it when the ignition is turned off?

Any thoughts on this?

FYI not sure what circuit I have wired the UHF into. I used a power circuit that was left after an in-car telephone kit was removed. The circuit does not have power when the key is in the off position - only in ACC or ON.

[NFI]

Originally Posted by TheOoz

I put a UHF in last weekend, and now when I turn the key off (XJ) the radio seems to have power for a few seconds more than it used to.

If I unplug the UHF wiring (power) the radio returns to the standard "almost" instant power down when the key is turned to off.

I don't think I have a problem, just thought it was an odd result as it seems like the UHF is storing power and the radio is using it when the ignition is turned off?

Any thoughts on this?

FYI not sure what circuit I have wired the UHF into. I used a power circuit that was left after an in-car telephone kit was removed. The circuit does not have power when the key is in the off position - only in ACC or ON.

Yeah I had this issues with my Suzuki Grand Vitara.
The issue was that the UHF Radio capacitors held a charge for a few extra seconds. Therefore the RADIO took longer to turn off.
It sounds like the same issue with your JK.
Did you wire to directly to the car battery or the accessories?

At least that what the issue was with the GV. Did not cause any problems si I did not wary about it.
However, this may be different with jeeps though.

[Gone]

UHF has power only when accessories turned on; it is fed off the acc circuit. UHF is wired in parrallel with the radio so when acc is circuit is turned off the capacitors in the UHF discharge thru the radio. If you turn the radio up real loud when you turn the key off, you should notice the radio turns off quicker.
-sparky skotup.

[mischf]

Originally Posted by skotup

UHF has power only when accessories turned on; it is fed off the acc circuit. UHF is wired in parrallel with the radio so when acc is circuit is turned off the capacitors in the UHF discharge thru the radio. If you turn the radio up real loud when you turn the key off, you should notice the radio turns off quicker.
-sparky skotup.

Either that or he is using switched ignition as the supply for the UHF (not what its designed for but you will get away with it). Do the lights on the radio fade after you turn the ignition off or do they shut off as normal but with a short delay. Sounds to me like the UHF is discharging through the ACC line to the radio, which keeps it awake for a short while. The radio has a continuous 12V supply (thats how it remembers presets), it will only turn on when ACC is supplied with 12V as well.

Most UHFs only have a B+ and ground wire, I don't know why they're designed like that apart from simplicity or so you can use the radio at any time. Switched ignition is not designed as a 12V source, it is designed to switch relays and in turn supply power from the battery. If you look at all your accessories (horn, cigarette lighter, windows etc) you will find they are all wired up that way.

[TheOoz]

The lights on the radio don't fade as the power drains down, they shut off as normal with a slight delay.

Are you suggesting that the UHF should be wired to a constant 12v supply so that it is only turned on and off at the UHF switch? It is easy enough to swap it over if that is the ideal. In fact, there is a female spade clip right next to the ACC one that I found which is permanent power so it would take 2 seconds to swap it.

[Gone]

Ide just leave it if it were me, but if the radio delay irritates you that much then feed it from a constant supply and manualy switch uhf on/off, but otherwise i dont think there is any real right or wrong way as long as its protected by a fuse size that suits the wire size. ie. dont feed your little uhf wires off a circuit designed for a winch.

[TheOoz]

Nah, doesn't irritate me that much so if it isn't causing any issues then I'll leave it. I just hadn't experienced the phenomenon before so was interested to know what was causing it.