khnitz

Re-posting here...I thought I was in the 993 forum when I first posted this, but I was in the 911 forum, instead...

---

'97 993 - Radio won't turn off with key
Here's the problem: with an aftermarket Blaupunkt radio, when the car is turned off, there is a momentary "blip" where the radio starts to turn off ("Go..." is visible of the Goodbye message for a moment), but then the radio stays fully powered on. I'm trying to help my friend sort out what may be wrong with his wiring that this would happen.

The background: I'm helping a friend sort out the audio system on his 911 - it's a 1997 C4 that had the Hi-Fi sound option. When he purchased the car, there was an aftermarket deck in the dash and the amplifier connector had been by-passed (a total hack-job on the wiring). I repaired all the wiring back to its factory original configuration so that we could re-install the correct Nokia amplifier. At that time, he just wanted speakers on the rear deck. So those were left connceted, and a pre-amp unit (a VC1 from V8A - V8Audio) was installed out-of-sight behind the dash for a minimalist look. The factory radio mounting location was used to relocate the switches from the center console. too.

Smash-cut to now, and with some changes in taste, the rear speakers have been removed and speakers are now in the front doors again. Also, a modern Blaupunkt stereo was installed. The "won't turn off" issue is the last thing to sort out this upgrade. I have verified that there is constant power (battery) and Ground at the proper pins of the radio, but what should be the switched ignition signal on pin 7 (in the wiring diagram, this line is labeled as "R" ?) is at a voltage just below battery (Battery=12.8VDC, "Ignition"=12.4VDC). It also measures a momentarily blip at key-off, but then recovers back to ~12VDC almost immediately.

Any thoughts on what may be happening are appreciated! What else does the "R" signal line connect to? Could it be the result of a bad ignition switch or power distribution relay? In searching the forums, those seem to come up as possibilities, but not with the symptoms he's seeing.

deekay911

Sounds like it may be wrong wiring, but if the wiring turns out to be correct, I had a similar issue which turned out to be a bad ignition switch. The radio stayed on for several minutes, then would appear to go off, what was happening was that there was residual power when the ignition was switched off, not enough to fully power the radio on (hence why it would 'die' after a while), but the drain killed the battery within 3 days, so I knew something was up. New switch (just the electrical part that connects to the back of the key barrel) was about $80 on eBay and a two hour swap. You have to take the seta out to lie on your back to get up under the dash

khnitz

Thanks for that BTDT help. I'll double check the wiring, but I confirmed that the VBatt is sitting at a little higher voltage than the R-circuit, whcih would make sens if the R-circuit passes through a protection diode at some point before reaching the radio. It is weird in that there is a momentary blip low (like it turns off), and then the voltage on the R-circuit returns high and keeps the radio awake.

I'll have to test the R-circuit closer to the ignition switch (or at the switch) and observe the behavior. My next chance to do that may be on Thursday evening.

Dplus

I have a CDR 220 in a '95 using the factory wiring and plugs and the radio operates without the key on; I thought they were all like that.

D.

khnitz

I agree, it should operate without the key on by waking it back up with a power button press. I have this same behavior on my VWs.

But, the radio should should shut off with the ignition/key off, first. The problem he's having is that the radio will not shut off with ignition/key off. It momentarily looks like it's going through its shutdown procedure, and then returns to full on.

I was able to find clean wiring diagrams through my local library's online resources, and the R line runs straight from the ignition switch to the radio (no fuse in this path). The battery feed to the ignition switch is uninterrupted (not even a fuse in that path, either), so this really limits the issue (barring other messed up wiring repairs somewhere else in the vehicle) to the ignition switch. I'll focus my investigations there, for now.

deekay911

Here is the DIY I used when I replaced my ignition switch:

Ignition switch replacement

geolab

Please, remove the radio unit from the dash, leave all connections, and try.
If wiring is sane, it will shut off.
What is happening is that the radio rectangular chassis is touching the car chassis (-)
The radio chassis SHOULD be separated by the dash vinyl from the car's metal (ground)
regards

vincer77

The radio is turned on/off by switching ground?

pp000830

Does the radio cut out when you have the key out and then open the door?

khnitz

deekay911: thanks for the link to the DIY - that will be helpful

geolab: with the radio connector unplugged and measuring at the connector between Ground (pin 8) and the R-circuit (Pin 7), at key-Off the voltage momentarily blips low, but then comes back up. Almost like there's a capacitance that's discharged and then built up again. very strange. The Pin8 ground of the radio is connected through to the metal chassis of the radio, anyhow, so I wouldn't believe it to be a grounding issue.

pp000830: No, the radio stays on with the key out and the door open. The interior lights do switch on and off with the door open/close (as long as the entry/alarm system is in the right state, too) - that was just a check of the door switch behavior.

From the wiring diagrams, the 993 shouldn't have a delayed off on this R-circuit (BLK/RED wire). At key off, voltage is removed. In all other positions of the key it should be On. Really makes me think it is the electro-mechanicals of the ignition switch. The R-circuit supply is pretty straightforward: Battery-->Ignition Switch-->Radio Connector pin 7. No fuse in the path. No load-reduction relay for starting in the path, nothing (from what I could find).

geolab

With all my respect, what you explain is your logic.
If you want the solution, I am telling you that it is the DIN bracket-frame attached to your dash touching ground. The metal rectangle that you slide the unit into.
Just slide the radio out , leave connected, without it touching the frame-bracket, car on radio on, switch of the car keys. It will turn off.

I am not talking about the radio metal exterior. each auto radio has a metal bracket DIN that the radio slides into. I call it chassis , sorry, I should have said DIN bracket?

khnitz

geolab: We'll give that a try then, too, if the ignition switch tests out OK. Electrically, how does the DIN bracket touching the radio chassis touching the dash panel affect the signal at Pin7 on the R-circuit? The ground connection at Pin8 should be tied to the radio chassis for ground, that I get. As for the logic, is it just that this electrically floating dash is some goofy Porsche logic ;-) Thanks!

vincer77

My radio does have a delay off after turning ignition switch off.

khnitz

vincer77: do you have the factory radio installed, still, or an aftermarket unit? If aftermarket, then what brand? Thanks!