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Probably isn't water Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Wed, 23 Jan 2008 05:15:24
In Reply to: popping fuse 9, Cal Aero, Tue, 22 Jan 2008 21:09:13 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Moisture is a lousy conductor of electricity, even when it's contaminated with salts (pure water is a decent insulator). At least in terms of blowing a 30 amp fuse. 30 amps is a lot of current, and when a fuse flashes, that's decent overcurrent. With 30 amps at 12 volts available, that's 360 watts - any moisture would evaporate first.
Most likely you have a frayed or crimped wire that is touching ground somewhere. Since you saw the fuse blow when you shifted into reverse, that implies that the short is at the back-up light switch or the back-up light relay (or the wire between). It's NOT at the back-up lights themselves - they are on a different fuse. Shifting into reverse closes a switch which actuates a relay, and that relay turns on the back-up lights.
Fuse 9 does supply the sunroof, cigarette lighter, and backup lights. An apparently, your radar detector, GPS, and clothes dryer.
First, I assume you're using 30 amp fuses.
Second, I assume you can disconnect the detector and GPS and still blow fuses. If not, inspect the wiring.
It does get confusing when you can blow the fuse by both opening the sunroof and shifting into reverse. That wire goes in three different directions (sunroof, cig lighter, back-up light switch). Since the fuse blows when you activate the switch, the short has to be on the side of the switches away from the fuse. And those points aren't common.
So I'm going to assume that you have an intermittent short due to a frayed wire, and that it makes contact due to movement in the car- shifting into reverse or opening the sunroof. The only other explanation is that you have intermittent shorts at both the sunroof and reverse switch, and that's just too hard to swallow.
I'd start troubleshooting the cig lighter socket, because that's the easiest to reach. Pull it out and check it for worn wires, burned insulation, etc. It gets a lot of abuse plugging things in and out. Next, I'd look at the transmision side, mostly because the wiring to the sunroof is hard to access.
You didn't mention which transmission you have. For an Automatic, the backup switch is part of the shifter mechanism under the center console. For a manual, it's on the left side of the gearbox. Since the fuse didn't blow when you weren't in reverse, then the fuse side of the switch is probably OK.
Pull the Reversing light relay out of the relay panel. Car off, stick an ohmmeter into pin 86 of the relay socket and measure resistance to ground. It should be a high resistance - or at least over a couple of hundred ohms. Pin 87 should be ground. If pin 86 is a short to ground, then you need to start troubleshooting it. If it's an open circuit, the problem is the relay.
If pin 86 is a short to ground, I'd inspect the switch and the wire that goes from the switch to the back-up relay. On the autobox, that is the green/white wire. On the manual, not so easy; both the supply and wire to the relay are white. There is also a splice that goes to pin 13 on the ECU (also white, no matter which tranny).
I'd look for wires that are crimped (trapped between metal bits) or worn/frayed. If you're pulling 30 amps on a regular basis, there will also likely be some signs of burning and melting insulation.
If that looks OK, then it's the sunroof. The switch is in the panel, but goes up to the motor/relay assembly above the rear-view mirror. Pop off the plastic cover and you can see it. But the wiring goes up through body pillars, and the problem is likely there. Not sure how to help with that.
posted by 192.249....
, Thu, 24 Jan 2008 06:26:53, Fri, 25 Jan 2008 05:41:53, Wed, 23 Jan 2008 05:15:24 <-- Viewing This Message
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