Stereo install, no 12V, help troubleshoot - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Hi Guys and gals, hoping for a little help here. Today installed a Clarion Head unit in place of my CDR-210. Read up on the pelican parts how to. But, I can’t get it to work. Bottom line is no 12V constant power from the engine loom (red/black wire) A few bits of info. I removed the stock head unit frame (that sheet metal thing) that had the security ground wire attached to it. When I installed the frame for the unit, it did not have a way to attach the security wire to the new frame. I read that I was supposed to ground the security signal, so I combined the head unit ground with the security wire ground. I checked for continuity from the negative battery lead to my grounding connection and there is continuity. I got everything connected, and it worked, but the HD Radio tuner wasn’t working, so I pulled the head unit out of the dash, and noticed that the HD radio connector had come undone when I was stuffing everything together. So I reconnected the HD tuner connection and put the stereo back in and turned it on. Nothing happened. When I lock the car, the car locks and there is the single horn honk (normal is no honks). I believe this can be attributed to the radio, but since I grounded the security wire, I’m not sure why I’m getting this. Does the car think the radio is gone, and if so, cutting power to the Constant 12V of the radio? So I started troubleshooting. Here’s what I’ve done: 1) I checked all the fuses in the floor panel. They are all good 2) I’ve checked the multimeter to the 12V switched wire, and it gets 12 V when the ignition turns on. 3) I’ve checked the multimeter to the 12 V constant wire (at the head unit and at the chassis harness. I’m not getting any signal there. All of the troubleshooting says this is usually a fuse, but I can’t find a blown fuse. 4) I ran a lead directly from the battery terminal to the 12 v constant and the stereo worked. 5) The cigarette lighter 12v constant works fine 6) I took the battery to the auto parts store and had it fully charged. Any help is much appreciated. I’d like to get it to work the right way, and don’t want to run a bunch of rogue wires around on my Porsche, that’s what the Honda is for….

Wait. If I read this correctly, the first time you hooked it up, the head unit had power bust you had no HD radio, correct? You pulled HU from dash, secured HD radio connector and now the HU has no power. Fuse? Power wire in the loom connector or the wiring kit is open.

Hi, yes, it did work until I pullid it out and reconnected the HD radio wire. Also, when I ran the chassis "12V switched" signal to both the head unit's 12V switched and 12V constant, the head unit worked. Problem seems to be with the 12V signal in the porsche loom. Is there a way to test this upstream somewhere? Anything to do with the alarm?

If it were the cage ground, I believe the alarm would sound when battery was reconnected (you did have it unhooked for the install, right?). The single honk is probably the console lid, but hard to tell. Fuses B2 and E1 should be replaced (may look good, but still be bad). E1 is related to both the radio and the central locking system.

The radio security wire should not be grounded. Always test for current with a test light, a voltmeter is useless. Connect the light to your power and ground sources.

Quotes source post: 427693

Yes, the brown/blue wire needs to be grounded or the alarm will sound. Pelican Technical Article: Changing Your Boxster Stereo Head Unit / Installing Boxster Ipod Integration - 986 / 987 Take it from an engineer; a "test light" is antiquated and doesn't tell you anything about power (actual current and voltage), only that you are completing a circuit. A multi meter is much more useful.

swap 12V constant and 12 switched. Even though you have connected them correctly (color to color), they are backwards. Went through this last winter with new JVC head unit and the Boxster wiring harness adapter.

Quotes source post: 427700

The way he is using a voltmeter tells him nothing about current. On my 98 the alarm sounds when the radio alarm wire is grounded. Don't know what year his car is....guessed an early car since he is replacing a CDR-210.

Multi-meter, not volt meter. Sorry for the confusion I'm not sure about the security wire; It may vary by year. A test light won't tell you anything about current, either. Current is measured in amps and the only way to measure that is with an ammeter (on the multi-meter). Though, the point is moot. You can't check for how much current something is drawing if there's nothing connected to that circuit. In other words, that may be a 200W stereo (meaning that it would draw about 16.6 amps of current when on), but there's no way to check for current if it won't power up in the first place. A wire not connected to a completed circuit doesn't have any current on it, only a potential voltage (the test light would draw a current, of course, but there's no way to measure the actual current other than looking at how bright the bulb is). I get what you're saying, though. A test light is much easier to use, but a multi-meter will give you more precise data. Either way, I still think it's a fuse Anyway, I'm sure he will get it figured out with everyone's help. I have to go now.

In regards to troubleshooting 12V issues in cars, a voltmeter will often show 12V (phantom currents) due to bad connections and grounds. A test light verifies that current is actually flowing enough to brightly light the bulb. Been troubleshooting and rewiring electrical systems since the sixties.

thanks for the help everyone. Particlewave, the idea to check continuity from the fuse to the 12V power is what helped me solve it. I had continuity from one end of the fuse, not the other. So the fuse was blown! Maybve there was still enough contact in the fuse to register continuity, but not enough to run the 12V, because I checked B2 about 5 times before my original post. Glad that's all the problem was.. My car is '97. "On my 98 the alarm sounds when the radio alarm wire is grounded. Don't know what year his car is....guessed an early car since he is replacing a CDR-210" What should I do with the radio alarm wire? I am still getting the honk. You guys are great, btw. Really appreciate the info. I've had my car for 10 years, and this is my first time posting to the board.

Had this issue recently on my car, as I understand it the original head unit has a felt sheet that prevents circuit meeting when alarm wire installed, ensures if parked with hood (English) down and someone tries to slide unit out the wire earths and alarm sounds. In my case simply disconnected and insulated wire and all good. No alarm feature on radio but heh park with roof up!!! Don't leave as it is or if cage meets with radio the system will earth and sound alarm. Not good at 4 am as I can attest, neighbours not best pleased.

If it is just a short honk and it does not put the car in full alarm state (lights and horn), the honk is most likely not related to the radio alarm wire. More likely the glove box or one of the doors or one of the hoods is not reporting closed to the alarm system. Ground the alarm wire and see if the alarm goes off, if it does, insulate it.