TSP

My wife has a 1997 986 as a summer car. Will turn over 100K miles this summer. Occasionally, when one turns the key, it doesn't engage the starter. The dash lights come on, all the warning lights are on but no starter. I, in my infinite wisdom, figured it was a bad ignition switch. I changed it with a new one from Pelican. Still does it. I then figured it must be one of the lockout switches on either the clutch or the brake, so I changed both of those... Still no joy. It has never left her stranded, the second or third turn of the key and it starts perfectly normally. What should I be checking next? The computer module under the seat? How do I check? Who repairs? Any thoughts would be greatly appreciated.
Tim

Anker

The problem may be in the starter itself. There's a solenoid that witches the high current circuit to the starter on. Solenoids do go bad. When she turns the key on a non-start, do you hear a click?

TSP

No, no click. Just the dash lights, accessories and all the warning lights illuminate.

Macster

Well, I would have offered up clutch interlock switch or possibly a bad ignition switch, but you have already addressed those two things.

Unless the cabin has had water in it and the computer module -- security module -- under the seat shows signs of moisture damage I'm thinking there is an intermittent problem with the RFID pill communicating with the security module.

Do you have a 2nd key, even a valet key, to try? If a 2nd key works better then the RFID pill in the "bad" key is suspect.

If car behaves the same with all keys then the signal path from the security module to the antenna behind the ignition key surround is suspect.

A tech with a proper Porsche diagnostics computer can query the security module for any error codes that might shed light on the intermittent no start condition. The security module might offer up something like: "Key not recognized" or "No RFID received".

Kind of a long shot but be sure the battery electrical connections are all good and this includes the connection at the starter solenoid and grounds.

CalSierra986

I had a similar issue on mine. I finally sent the immobilizer and DME to be tested by ECU Doctor. The devices tested OK. When they came back and were installed, the car worked find. Mine is a 97 Boxster 986, 144,000 miles w/ TIPI am looking for a reason my DME relay is drawing down my battery. I have been driving it for 5K miles or more with this issue. If I leave it sit 6-7 days, the battery goes dead. 3-4 days its Ok, but low and needing a charge.Using a Fluke DVM and .01 ohm resistor I pulled fuses until I found where the current draw is. Fuse - B3 horn 140mAFuse - C1 DME main relay 550mAI have replaced the relay and sent the DME, immobilizer and key to be tested. The car failed to start. It seemed to be heat related to 100 degree days. Car has always started since they parts were returned from ECU Doctor and re-installed.When first connected to the battery the measurement is 160mA I assume this is normal.After turning on the ignition and then off. The value jumps to 1.25A until the dash lights time out and returns to 840mA With the radio on I measure 310mA. With both fuses removed it is back to 150mA (I assume to be normal)The horn is inop, so maybe a trip into the steering wheel is in order, but why the DME current draw? That's over 1/2 amp.
Does anybody have any ideas?'

mikefocke

Typical draws are listed here.

TSP

Alright...
First, thanks for the thoughts. Happens in the same intermittent fashion with all keys, including the valet key. I think I am going to have to spring for diagnostics at a dealership. Bit of a pain, the closest dealer is 4 hours south of me and no independents I know of who can troubleshoot. Thanks again for the input.

Macster

I know you replaced the clutch interlock switch but this may still be the problem. You have to be sure that when the clutch pedal is depressed -- all the way -- the switch plunger is fully pushed in and the clutch switch is activated.

Before you go to the trouble of hauling the car 4 hours to a distant shop you might search for how to do a clutch interlock switch bypass and eliminate a bad (new) switch, or excessive play in the clutch pedal hardware that doesn't always have the switch plunger fully depressed.

grrrmonster

Or bad ignition key switch

mikefocke

What does the tach do when it doesn't start? Bounce a bit or not move at all?