2000 986S electrics

[Anser]

Well, after all spring and up until last night, was the car running without any issues.
The wife was out and about visiting clients when the problem reoccurred.
The car would just quit running. All dash lights still worked.

B8 fuse blown (DME and Immobilizer fuse) was replaced plus I had a spare fuel pump relay I installed. It fired right up.

The car ran like a top except for once a slight hesitation with a quick CEL flash.
After that no problem. We were about 20 miles from home.

I got home and hooked up the Durameteric, and no codes were present.

My next step is to go though the wiring harness for the DME and Immobilizer again and check for chaffing of wires somewhere. Yea, high 90's with matching humidity this weekend!

Any suggestions for helping track down this issue would be greatly appreciated.

Thanks!

[Gilles]

Anser,

I had a similar issue with my '07 987CS, not sure if your car has the same electrical box, but drove me nuts until accidentally found the culprit.

It was the No. 4 (positive cable from the battery to the distribution box), where it connects to the distribution box at the firewall, it's fairly easy to check.

PS: No. 11 is inside the cabin, behind the glove box, but the connector side is on the front trunk..

[Anser]

Thanks Gilles.
Checked it and the nut was tight. Still has the factory paint stripe on it.
Your idea lead me to look at the high current distribution box.
Thinking a loose connection could cause a surge.
I asked if she hit a bump when it happened, and she did.


I went to move it to have more room, and now it blows the fuse immediately.


Ideas?

[blue62]

Sounds like you need to test the wiring harness for a short with a volt meter.
If you have the Bentley service manual there is a description on how to locate a short on pg. 97-39.

[Anser]

That is the plan.
I do have a better feeling about finding the cause now that is a solid failure!

[blue62]

Originally Posted by Anser

That is the plan.
I do have a better feeling about finding the cause now that is a solid failure!

Yes a solid failure is a positive, chasing intermittent failures can be very frustrating.

[Anser]

Short from load side of fuse B8 to gnd.
Seem to be in the harness that feeds the relay box in the trunk. I was able to create or fix the short by pushing the harness close to the relays.
Pulled the relay box out and it never shorted. Was even able to fire the car up without the fuse popping.
Got as far as unwrapping and inspecting the wires, but nothing definitive yet.
It's in dare somewhere........