Radio/CD suddenly dead

[yerog]

I have a 2007 Toyota Yaris and the unit has suddenly died. The problem is not fuse related because the dimmer light which is on the same fuse is working ok. Any Ideas?

[CTScott]

The dimmer fuse is just for saving the radio station memory when power is off. The ACC fuse powers the main functions.

[bobolinko]

The dimmer fuse is just for saving the radio station memory when power is off. The ACC fuse powers the main functions.

Hi CT,
I have a question to that end...
My Scion XD stereo looses all the presets when the battery is removed, but remembers EVERYTHING when I disconnect the power cable (battery power still live) from the unit and remove the head unit and store it, even for a year or more... What's the goings on here?

I cannot understand why this happens, but it does. Did it more than once, and on more than one car.

Thanks!

[CTScott]

Hi CT,
I have a question to that end...
My Scion XD stereo looses all the presets when the battery is removed, but remembers EVERYTHING when I disconnect the power cable (battery power still live) from the unit and remove the head unit and store it, even for a year or more... What's the goings on here?

I cannot understand why this happens, but it does. Did it more than once, and on more than one car.

Thanks!

At first I was thinking you are nuts, but then I realized that the radio probably has a super cap for memory backup. When you remove the radio it keeps the CMOS alive for a long time, but when you leave it in circuit, it tries to power the rest of the car when you pull the battery cable. Put a general purpose diode (1N4001, etc) in line with the constant battery power wire, with the white line facing towards the radio. That will prevent it from back feeding the rest of the car.

[bobolinko]

At first I was thinking you are nuts, but then I realized that the radio probably has a super cap for memory backup. When you remove the radio it keeps the CMOS alive for a long time, but when you leave it in circuit, it tries to power the rest of the car when you pull the battery cable. Put a general purpose diode (1N4001, etc) in line with the constant battery power wire, with the white line facing towards the radio. That will prevent it from back feeding the rest of the car.

Thanks CT.
I, too thought I was "losing it" so I had to do it 3 times and sure enough, each time the results were the same. I was thinking about the diode, but have not had the motivation to getting into the dash again. It just might be the same with the Yaris radios too...

[CTScott]

Thanks CT.
I, too thought I was "losing it" so I had to do it 3 times and sure enough, each time the results were the same. I was thinking about the diode, but have not had the motivation to getting into the dash again. It just might be the same with the Yaris radios too...

No. The Yaris ones lose it instantly either way, which would lead me to believe that the Scion harness or fuse panel has the diode integrated.

[bobolinko]

OK, heres thescoop:
Since we started the discussion, I got enough motivation to jump in and try the installation of a diode to the 12v Constant supply wire. I had considered a switch or diode and went with the diode to have less hassles in the future. I cut the constant supply feed line and soldered in a small rectifier (3 amp) and heat shrinked insulation on it. Installed the radio, and all the presets still were intact. removed the battery and serviced both ground and positive terminals which took about 20 minutes. Waited about another 15 minutes and re-connected the battery terminals. The head unit's presets were still intact! I am sure there is a cap in the head unit that keeps the volatile memory alive during periods of disconnection. I cannot understand why Scion had not intalled a 75 cent rectifier in the harness to make life so much easier for it's buyers! If the Yaris has no facility for this, an installed cap and diode would surely do the trick! All is now good, and thanks CT- for kicking me over the edge to do the mod! The Band side (Cathode) goes to the HU and the other end to the wiring harness.
http://i602.photobucket.com/albums/tt107/bobolinko/rectifier.jpg