Hi Rennlisters,

Happy New Year!

I recently purchased a 987.1 Cayman S with 126k miles and would love to get your thoughts on an electrical issue I’m dealing with. Below, I’ve outlined what’s happening and what I believe might be the cause and solution.

When I bought the car, the previous owner mentioned an issue with the ignition switch. He stated, occasionally, the car wouldn’t crank, and after turning the key fully, the engine would click, then the battery would lose power. He recommended keeping the frunk open and disconnecting the battery terminals while waiting for the ignition switch replacement. The battery is brand new, replaced just a couple of months ago.

I’ve had the car for about three weeks without experiencing any ignition switch problems or electrical issues. Everything worked perfectly—no starting trouble, no electrical faults, and the car passed a PPI, including the ignition switch, from a reputable independent shop here in Orange County, CA.

However, today, after replacing the cabin and engine air filters, the electrical issue started. After finishing the replacements, I got in the car, inserted the key, turned it, and while the dash lights came on, the engine clicked but didn’t start, and then everything shut off completely. It was as if the electrics weren’t drawing power from the battery after cranking. The only way to restore power was to disconnect the battery terminals, wait five minutes, and reconnect them. Even after several attempts, the same thing happens: I turn the key, the dash lights up, there’s a clicking noise, and then the battery and all electrics shut off. Unfortunately, the engine does not actually fire at this time due to this issue.

Thankfully, the car is parked in my garage while I wait for the new ignition switch to arrive.

I’d really appreciate your insights—based on these symptoms, do you think the ignition switch is the primary issue? I look forward to hearing your thoughts and greatly value your time.

 

Here is some general theory that may help you out.
The physical key, with its unique pattern, is inserted into the little cylinder on the left side of the dash. I don't know the physics but the cylinder has wire coils that passively read your key pattern and convert it into a unique digital signal. It is relatively inexpensive ($50ish) and is a pretty easy DIY replacement. Base on your symptoms, I don't think that is your problem but if you can do it yourself, it is a cheap "rule out".
The next most easy "rule out" is the battery. They can get strange. Even if you think it is "new", I would replace it. It is certainly a DIY thing and is easier than what I'm going to talk about next.
BTW, when you put the key into the ignition, your car, like mine, should make some minor clicking noises from the engine compartment. That is normal. When you move the key to the run position, every light on the dash should light up. This is so you can make sure all the annunciations are working. When you move the key to the start position, usually the cranking of the starter is the loudest noise by far. But if say your starter is not getting full current, you may hear a rapid clicking noise, or you may just hear a singe click.
If there is corrosion buildup in the various electrical connections between your battery and the starter, you can get strange behaviors. The connection will pass low current but when you hit it with a large current, such as starting the car, the connection fails open. I would start by removing the cable from the battery negative and at its other end to the body. Get some dedicated cleaner from the autoparts store or just us a mix of baking soda and water. Get some sandpaper and clean up the connectors. There are special tools at the autoparts store that clean the lead post on the battery and the inside of the clamp. These are the easy ones to get to but remember, good grounds are just as important as the positive side. If that doesn't fix it, there are several cables that go from the positive terminal back to the starter. Any of these connections could be corroded. If you get to that point, there are multiple threads by folks that have replaced these cables. Use the Search function here or just Google it.
I hope that helps.
HarveyF

 

the original poster did not say if the car was a manual or automatic. I had a problem with a finicky restart of my Cayman S 6-speed. It turned out to be the clutch interlock switch. The switch wasn't bad, but the bracket was bent enough where it would only start if the clutch was fully depressed. It was easy enough to bend the bracket so the car would crank with the pedal mostly depressed as in a panic restart after a stall.

Also what is the state of charge of the battery? Resting is it above 12.5 volts? Are the battery terminals clean and tight?

 

I'll echo some of what @harveyf said, and add some of my recent experiences with screwing up my car and giving me some bad loss of electrical power.

On the positive side of the battery, investigate the whole cable, including the part that connects to the firewall. The firewall connection is a strange connector. The part on the cable is a weird, helical set of contacts that make contact with a rod. There are a couple of failure modes on this side of the cable. The first is that there is oxidation inside the cable connector. The other mode is that there is oxidation on the connector pole itself. In my experience with it, be careful with cleaning it (the rod) too aggressively. I don't know what it was, but there was a highly reflective layer on the pole that was apt to flake off once there was some oxidation underneath it. If you really want to dig into this, you can look up posts for 997s and hard starts. If you really want to go full Pineapple Express, you can find my post where I replaced that connector and cable to a more traditional, bolt down type.

The other thing I did that was really messing with things was to install a quick disconnect on the negative terminal, because of how much work was being done to get the car running normally. While I have had good success with these things on other cars, I found that this arrangement was causing me to lose all power to the car every so often, right when I was trying to crank the engine. The symptoms sound exactly like yours: turn on the key to let the oil check happen then when I would try to start the car, total shutdown. I would have to do the whole battery on the fuse panel thing to pop the frunk. I'd investigate, wiggle some cables and then the car would behave normally. My point is, really take a look at the battery ground, as well, as this was the mistake that I made and the root cause of the issues for me. That's a nice, easy one, as it just bolts to the wall of the compartment and can be removed for inspection easily.

Good luck

 

i too will check this out, thank you

 

I wanted to follow up with an update. First, thank you to everyone who replied and shared your valuable insights!

The issue turned out to be the positive terminal cable running from the battery to the firewall. The section emerging from the firewall was heavily corroded, which likely played a significant role in preventing power from reaching the starter motor.

Removing the cable was challenging due to the corrosion buildup, but with rubber-tipped pliers, plenty of wiggling, and a lot of patience, I was eventually able to get it off.

After removing the connector, I used various grits of sandpaper and rotary tools to clean off the corrosion from both the connector’s inner diameter and the post itself. Once most of the corrosion was "gone", I applied dielectric grease to both the post and the connector’s inner diameter.

The car started right up after this process, confirming that the ignition switch wasn’t the issue in my case. Below, I’ll share some before-and-after photos for reference. Hopefully, this will assist others dealing with similar electrical issues or a non-start condition.

 

at 9:35

 

Wow, that does appear to be a "smoking gun". I'm glad you found something so quickly.
I'm no expert on modern electrical system hardware but that how does that female connector "clamp" onto the post? Anyone?

 

Thank you for the follow up, and pictures. I am a bit confused though on how the cable is attached to the post. I see a "ring" machined around the post. Is that what "latches" the positive cable in place?

Thank you

Rich

 

There is a red clip that slides back, away from the post toward the wires, which disengages the clip locked into the indent ring on the post!

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You beat me to it—the weekend got really busy! I used a flathead screwdriver to push the tab downward. Mechanically, it works by having a key (collar) that’s part of the red plastic tab. When pushed upward, it catches the front groove on the metal post, and once retracted, the plastic key disengages.

It’s worth mentioning that when my post was heavily corroded, the plastic terminal wouldn’t disengage (even after moving the red tab downwards) because of the buildup. To address this, I used rubber-tipped pliers to grip the plastic terminal and rotated it clockwise and counterclockwise repeatedly—likely hundreds of times—until I was able to gradually work the plastic part free from the post.

After that, it’s up to you how you clean both the post and the inner diameter of the plastic terminal. I shared my preferred method in the last message.

Happy wrenching!

 

Here's a great video also showing this fix