Instruments off, wipers on

[JE 17]

1000 miles from my home (and tools) my 2011 Cayenne turbo misbehaves. 

Headlights quit, instruments and all controls, including MFD and suspension controls go dark, while wipers start. I can't turn them off. 

Engine continues fine. 

Then, it all comes back. We repeat this several times as we drive through town. One time a check engine light came on, though it didn't repeat. Preset memory wasn't lost.

Research points to a ground problem. I did access the battery after an incident on the last trip traced to a bad connection on the right rear shock, which gave the the chassis system failure warning.

Anyway, no problems for 1000 miles until now. Research points to a ground problem. I have no tools to check battery connections, though I specifically recall tightening the connections.

So, any other ground points I should check, requiring no tools?

 

[Loren]

Any fault codes?

I think the cluster should be reporting faults.

[JE 17]

Have no code reader with me. Drove today, and had a check engine light, which went out eventually. 

I'm thinking the light switch may be the problem.

[JE 17]

No. Did it again without lights. First indicator is "start/stop disabled" followed by "headlight control fault."

 

[JE 17]

Made it home without further trouble. When we stopped overnight in downtown Lincoln, a check engine light popped up.

There were no indications of poor running, and it disappeared after one gas stop. 

I did notice every time the display died, the voltage was in the mid-thirteens. Most of the way back today, some 700 miles, it stayed around 14.7, and there were no problems.

[Loren]

How old is the battery?

A weak battery will give many electrical faults.

 

If it is over 4 years old I would replace it. If not, then get it load tested.

[JE 17]

The battery is one year old, and I just had it tested two weeks ago by Interstate for another issue.

Could this be an alternator or regulator issue?

I should add, the alternator was tested as well.

Edited February 25, 2023 by JE 17

[Loren]

According to your voltages the alternator seems fine.

Perhaps a bad ground?

Start with the battery to chassis grounding.

[JE 17]

Checked battery ground at the terminal, and just for good measure, gave it a Deoxit dose. I haven't driven it a lot since, so I don't know if that was helpful. The terminal was not loose, though.

I will try to find the other end when I am able to put it in the air on my hoist.

[JFP in PA]

15 hours ago, JE 17 said:

Checked battery ground at the terminal, and just for good measure, gave it a Deoxit dose. I haven't driven it a lot since, so I don't know if that was helpful. The terminal was not loose, though.

I will try to find the other end when I am able to put it in the air on my hoist.

Try running voltage drop test across both primary battery cables, Porsche has had problems with these cables developing internal corrosion that cannot be seen but causes all sorts of issues.

[JE 17]

That seems like a good suggestion. I got the warning signs again last night; "headlight control" and "stop/start disabled," yet it didn't lose the MFD or instruments.

Curiously, the voltage was reading in the mid-mid-thirteens, which is when the problem usually occurs. If it's up in the 14s, there is no dropout.

I'll try to do this, but it may be tough to accomplish as I'm about to move 1000 miles!

[JE 17]

A small update.

I lifted the carpet and checked the wiring, finding no obvious breaks. When I have more time (replacing HVAC fan in this one, Boxster oil change due, and going over new purchase) I'll take the seat out to get better access. 

But interestingly, have had no further problems after poking around the wire tray. I wonder if further investigation will show something loose in there.

I will stay with it and keep you informed of any findings.

[JE 17]

Additional update.

Several months have passed and no additional problems. I do get a "check left side marker" warning that is new, but it goes away. So I'll just wait until fall when the garage is under 90 and remove the seat to take a closer look---or why poke the bear?