sloanautomatic

with the sound my car is getting when I try to start it
What would you diagnose as the issue?

What I know: Without jumping the car I get ZERO signs of electricity on the dash, lights, nothing. If I jump the car with the terminal under the hood, I get the same ZERO signs of electricity. But when I jump the car directly to the battery under the driver's seat, I get dash/radio/locks/seat controls.

When jumping to battery under the driver's seat: If I turn the key in the normal clockwise way, no noise from the engine occurs. But when I turn it to the left and then the right, I get this noise, and the front headlights turn on and off quickly. It is my understanding that turning the key to the left first activates the back up battery. There is no back up battery installed in this car at this time. Only the one under the seat. Anyone got any ideas what this sound is telling me?

deilenberger

Sounds like a dead battery. If a battery is dead enough - jumping it with another battery won't be adequate to start the car. My WAG - you need a new battery. If you have AAA they offer battery service where they come to you.

Also - I've never heard of the left-turn of the key to activate the secondary battery. The Cayenne starter circuit is not like the usual key controlled starter. When you turn it to the right it tries to start and latches a relay that continues putting power to the starter until the engine actually starts and reaches a certain RPM. So - when you turn the key to the right initially, that relay gets latched and the starter simply stalls because the battery is so dead. When you then turn the key left, you unlatch the starter and the initial draw on the battery probably heats it enough to make it put out a bit more power - which is why your lights come on.

All of that may be baloney if your car is designed for 2 batteries and one is missing. 2004 is in the era where some do - some don't - have 2 batteries and the switching circuitry for it. Easy enough to check, look under the spare tire in the rear compartment - that's where the 2nd battery is supposed to live.

ScootCherHienie

If the battery is new/charged, then you could have a bad ground somewhere in the electrical system. One place a ground like that can come from is water infiltration into the interior of the car due to 1 or more plugged-up roof drains. Check under the carpet for moisture in the padding under the carpet. The carpet will feel completely dry when the padding is soaked underneath. If the padding is wet, water can get into splices that inevitably happen during assembly as they run out of 1 color of wire and have to change to a new spool. Those splices aren't waterproof and if they get wet, whatever the wire is carrying now has a path to ground with some resistance to help make it harder to find. This can often result in very slowly killing the battery over 3 days to 3 weeks (of the Cayenne sitting unused). The fix is removing the caps over the outlets of the roof drains and letting the water run out. The little caps trap bits of grit, and those trap smaller particles and before long, no water can get out of the drain tubes. Many people just leave them off and you never have to worry about them getting plugged up again. If the padding is wet, you'll need to dry the interior effectively with open doors and hatch with fans going... and even then, it takes days. You could try to run a dehumidifier inside the car if you have one that will fit inside if your weather isn't conducive to outside drying. The posts under the hood aren't very effective at getting "juice" to a dead battery, but they work fine for low-current battery maintainers, so it's not particularly surprising the jump start failed at the under-hood posts. But that the jump failed under the hood indicates the battery under the seat was fairly low in charge. So you may indeed have the plugged roof drain issue. There is a Roof Drain topic in the DIY section of this forum that will help you find the small roof drain outlets so you can remove the caps. If you remove the cap and nothing comes out, that drain was not plugged up. But if water runs out when you remove a cap... the cap itself was preventing the water from getting out. No "cleaning" of the drain tubes is needed (at least not that anybody has reported so far).

deilenberger

Actually it has nothing to do with running out of wire. The harnesses typically have 3 splices on each side, and the purpose of the splices is to provide circuitry for components in the area of the cable. These can be thought of as branch circuits, branching off the main circuit to provide a signal path to something local to the harness. Unfortunately, the way the splices were done, the failure of a splice can result in the failure of the main circuit. Porsche made this somewhat better in the 958 series, using a much better waterproof splice than the 955/957 have. The footwells still flood, but it's much less likely it will cause the seemingly random electrical problems the earlier failures do.

brett968

The first thing I would do is remove the main battery and take it to an auto parts store for testing. This costs nothing. I wouldn't speculate any further on why it isn't starting before doing this.

Judging from the state of things in the video, I take it this car hasn't run in a while? If you just got this car then I would advise restraint before putting any money into it. If the car has been passed around and/or was a "super" deal, it likely has something terminally wrong with it (like cylinder scoring). See if you can get it running (borrowing a battery is one option) and listen to the engine. Post a video with the engine running here if you would like some assessments. Keep in mind that piston slap from cylinder scoring is likely to go unnoticed in the early stages to the untrained ear.