My Dad's Cayman S has an electrical issue. It will refuse to start, dash lights up, and the frunk won't open. Once open the negative battery cable is hot.
He has already replaced the ignition switch (common issue) and cleaned the power distribution pin (TSB about it). It seemed to be fixed until tonight when it happened again. Anything online we have found points to the above two issues.
Any suggestions?
Thanks!
That hot cable suggests high resistance in it, maybe a bad connection at one end or the other. And how old is the battery? Especially on modern cars that are not used regularly (like a lot of Porsches), internal battery issues seem to cause a range of weird problems.
We are going to recheck the work done on the power distribution pin to make sure nothing came loose. Then check the cables and the starting circuit. It is something drawing high amperage when trying to start and causes a low voltage issue for the rest of the systems. Hopefully we can track it down.
Does the car crank over at all, or do you get noting when you turn the key?
In reply to Woody :
Nothing. Just dash lights up like a Xmas tree and the frunk will not open. Once open to reset the car he has to remove battery cable .Then fine for a while.
In reply to AnthonyGS :
Thanks! We will investigate that .
I’d suspect a bad cable. Similar symptoms on a previous car and upon careful inspection discovered corrosion under the new battery sheathing
PMRacing said:In reply to Woody :
Nothing. Just dash lights up like a Xmas tree and the frunk will not open. Once open to reset the car he has to remove battery cable .Then fine for a while.
I asked because I had a 2006 Cayman S with a starting issue, but it seems to have been something entirely different.
There are two main issues that I have found. Igniton switch goes bad is common. The other is a corroded power distribution pin. Both have beem addressed in this case. We are going to take a look this weekend. I will post what we find.
If the negative cable near the battery is hot theres a 99% chance the negative terminal is not making a good connection. The other 1% is that the cable itself has high resistance. The heat is not from flowing excessive current, it's from channeling the normal amount of current through a smaller than normal space in the wire. A funny thing about electrical circuits is that if you have a bunch of resistance on your ground path then everyting upstream of it will operate on lower voltage. So if you are dropping 4v across your ground wire, everything upstream of that wire is now operating on an 8v differential even though your 12v battery is still feeding it 12 volts.
Update time. So first off this is a random issue so duplicating it is difficult.
We did a voltage drop test between the battery and chassis ground. 12.3 to 10.3v. so there is an issue somewhere. Negative battery cable is ok but we will replace it anyway. We tested the starter relays and they seem to be working OK. No more corrosion found on the power distribution pin in the box. Still working our way down the chain to the starter.
Any other ideas? Thanks!
The wire will only be warm near the actual problem spot, so i'm sticking to my 99% statement above. I don't exactly understand what you mean about the voltage drop. A voltage drop test across a bad connection would generally only drop a couple of volts, and if you're checking a ground wire you would never see 10-12v unless there was an open circuit downstream of where you tested. Can you explain exactly what you were doing?
If I may offer a suggestion as I am going through the very same testing protocol but on a much smaller scale: At work we are chasing a voltage drop problem in an enclosed battery pack for a military infantry (I suppose that is a redundant pair of words) helmet mounted display. It's just two 1.5v batteries but we're losing enough voltage that the unit stops working before the batteries are flat. I had to drill holes in a battery pack to probe the batteries directly and measure the voltage getting lost at each connection when the unit is powered.
So what I think you want to do is measure the voltage (what we learned to call "difference of potential" in Navy electronics school) from the negative terminal ON the battery to each of the connections of the negative battery cable WHILE starting the car. Might be easier if you can make it so the car doesn't start but just cranks as that is the highest current the battery and cabling will see. None of those connections should show more than a coupla tenths of a volt of drop while cranking.
As an aside, I have fixed several cars with the weirdest electric problems over the years due to corroded battery post to cable terminals. Second to that is bad cables, followed by bad ground connections at the chassis. Hate to say but a few of those were with my own personal vehicles...
Well, my dad found some pretty heavy corrosion at the ends of the starter cables and junctions. He cleaned them off, but hasn't had a chance to drive the car much. We'll see if that helped, but it usually takes a few starts for the condition to reappear. I'll update if we find anything else. If this doesn't work, it will be a more thorough voltage drop test along the starting circuit. Thanks for the advice!
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