Battery died and was old, so I replaced the battery battery post and terminals were cleaned. Car will not crank. Read posts that it was probably the ignition switch, so I replaced the switch. Reinstalled the negative battery cable and tried to start the car. The car started immediately. Tried to restart and nothing. Disconnected the battery again and checked the cable. Reconnected cable, tried engine and car started. Turned engine off and tried to restart. Again nothing. Help, I am totally lost. Immobilizer under seat is dry. Does anyone have any suggestions?

I would check and/or replace the ground (negative) cable.
Doesn’t sound like an issue with the ECU.
Happy Boxstering
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

---

Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

I told him the same thing on another forum! :-)

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Anker
I told him the same thing on another forum! :-)

Another forum

"A mile of highway will take you one mile. A mile of runway will take you anywhere."

Yes, I can't remember whether it was 986forum or rennlist, but it is annoying to see posters put the same post in multiple forums and get exactly the same answers to their questions.

There was no indication that the OP had actually checked the ground connection before cross posting.

Maybe the battery was never dead....

That said, I've seen the ignition switch be very very flaky. Good, no bad, no, wait.

Grant

gee-lenahan-at-gee-mail-dot-com

Sorry, I forgot to say that I replaced the negative cable when I replaced the battery. Old cable looked okay, but I was trying to cover all bases. I am going to replace the chassis to engine strap next. Any others thoughts?

as noted above - get a meter and find out where the 12V stops.

As also noted above, the switch can be absolutely devilish - totally non-intuitive failure modes and intermittencies.
I have never had the pleasure on a porsche, but many on older Audis.

Starter connections?

In dash wiring?

Starter relay?

strange intermittence short somewhere that wires come close to each other?

The other night i had a strange short in a prototype piece of equipment was working on where some solder created a tiny "fiber" - almost invisible and bridge to chassis. THAT was a ball of fun to find.

G

Grant

gee-lenahan-at-gee-mail-dot-com

Thanks for the info.

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Moore2806
Battery died and was old, so I replaced the battery battery post and terminals were cleaned. Car will not crank. Read posts that it was probably the ignition switch, so I replaced the switch. Reinstalled the negative battery cable and tried to start the car. The car started immediately. Tried to restart and nothing. Disconnected the battery again and checked the cable. Reconnected cable, tried engine and car started. Turned engine off and tried to restart. Again nothing. Help, I am totally lost. Immobilizer under seat is dry. Does anyone have any suggestions?

With my 2002 Boxster I recall experiencing at least one no start event. No start with no cranking present.

My Boxster was equipped with a manual transmission. (I cover the Tip below.)

The culprit turned out to be a flaky clutch safety interlock switch. The switch can wear out, or the clutch pedal hardware can develop sufficient play the clutch pedal arm does not fully close the safety interlock switch, and everything looks normal when you turn on the key but the engine does not crank.

You can release the key and release the clutch pedal and then push it down again -- do this vigorously several times in rapid succession -- in hopes the switch resumes functioning and try to start the engine. I watched a tech do this to my Boxster when I had it in for the no start/no crank behavior. The engine cranked and started every time... But the switch still proved to be bad, stranding me late one night at a closed Porsche dealership.

Some recommend bypassing this switch and maybe you want to try that. I don't know the procedure.

What I did was to just get a new clutch safety interlock switch and while you are at it a new brake light switch and new cruise control disable switches for the brake and clutch pedals. The switches don't cost much and they do wear out. (My Boxster lost its brake lights when the brake light switch wore out.)

Replace these switches and double check the clutch pedal arm or whatever it is that touches the clutch safety interlock switch fully depresses the switch.

If you have a Tip equipped Boxster of course there is no clutch interlock switch. It is less rare this goes bad but whatever switch signals the Tip is in Park or Neutral may be bad -- or the whatever switch that signals the brake is applied may be bad (I believe the brake pedal must be applied before one can start a Tip equipped car) -- and the engine will not start/crank because of this. You can move the shift lever around from Park to Drive and back to Neutral or back to Park and work the brake pedal and try to start the engine. If it cranks well, at least you know. (I'm becoming more familiar with automatic equipped cars with my new Hellcat equipped with an 8-speed automatic. It just occurred to me a "telltale" the Tip might be a problem is if you do not see the P or N indicator on the dash.)

If you can't get it to crank at all and new switches don't help what can be going on is the RFID ID might not be making its way to the car's security module.

Briefly, when the key is inserted in the ignition and turned the security module issues an RF signal -- the antenna behind the ignition key surround. This signal is received by the RFID pill in the key module and this energizes the RFID circuitry and the RFID pill then issues an RF signal that contains an encoded ID number.

The same antenna receives this signal and the signal is carried to the security module where it is decoded into a digital value -- an ID number -- and compared to what is stored in the security module's non-volatile memory. If there is a match the security module signals the DME and the DME then allows the starter circuit to become active.

The RFID pill in the key may be bad. Try another key. Even the valet key. It has an RFID pill in its key head.

If this RF signal path is bad of course the signal may not make through. Generally this RF signal path is quite robust and trouble free but a heavy handed ignition switch replacement can cause a problem.

A tech can query the security module with the Porsche diagnostic computer and obtain one or more error codes that point to the problem. Something like ID not received/not recognized/etc.

A long shot, very long shot, is a battery disconnect will effect a "fix". With all electrical loads off and the key removed from the ignition switch -- write down the radio code before you do this! -- carefully disconnect the battery then with the battery disconnected press and hold the brake pedal down for a bit then carefully reconnect the battery. By doing this you are in effect power resetting the car's electronics. The behavior though doesn't read like a power reset will help. Still...

The car has a Tiptronics in it. I have tried everything mentioned in the posts thus far. I have not tried the trick with the brake yet, but will try that tonight. It still frustrates me that I can disconnect the negative cable, then reconnect the cable and the car will start. Then the car will not restart. I can repeat the previous procedure and get the same results. I am totally stumped.

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Moore2806
The car has a Tiptronics in it. I have tried everything mentioned in the posts thus far. I have not tried the trick with the brake yet, but will try that tonight. It still frustrates me that I can disconnect the negative cable, then reconnect the cable and the car will start. Then the car will not restart. I can repeat the previous procedure and get the same results. I am totally stumped.

That's very unusual and interesting behavior. I have never come across this behavior before.

A WAG is a relay is acting up. The removal of power "fixes" the relay but the one start causes it to go wonky again and that's that. But which relay?

Because it is so unusual you need to consider having a Porsche tech look at the car. If anyone has seen this behavior before, or heard about in training glasses -- techs at these week long classes love to swap "war" stories -- or it may be behavior the tech has to find and fix as part of the test he takes to advance up the ladder from a Bronze, to Silver to Gold tech, it would be a Porsche tech.

Thanks for the comments. I have order several new relays to try. I think that both the DME relay And the starter relay are the same. If that fails, I will have to take it to the dealer.

Received my new relays today. I also got my Bentley manual for the Boxster. Tried the relay with no changes in results. Referred to the trouble shooting section of the manual. According to the tests I ran, the DME relay is not getting a signal from the ECM. Do not know where to go from here. It will be 2 weeks before the Porsche dealership can work me in. Would be willing to listen to any advice. Thanks

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Moore2806
Received my new relays today. I also got my Bentley manual for the Boxster. Tried the relay with no changes in results. Referred to the trouble shooting section of the manual. According to the tests I ran, the DME relay is not getting a signal from the ECM. Do not know where to go from here. It will be 2 weeks before the Porsche dealership can work me in. Would be willing to listen to any advice. Thanks

A bit confusing, but ECM and DME are really kind of one and the same thing.

Maybe tonight I can dig out the factory manual with the Boxster wiring diagrams and go through them and see if I can find what ECM signal goes to a relay which is in a circuit that plays a role in the engine starting. Just thinking out loud, generally relays are used to let a low power electrical circuit control high(er) power electrical circuit. For instance headlights, fuel pump, and the starter motor.

Hopefully I won't be at work too much longer and will get home at a reasonable hour...

Thanks for your help. I am getting frustrated.

I'm guessing the car doesn't let you start unless you're in Park. I would check the wiring diagram for which wire that goes to the immobilizer is supposed to tell it that the car is in Park and see if that wire is grounded.

You can also as a quick-and-dirty test try wiggling the shifter and take it in and out of Park a few times to see if the car starts. It won't necessarily work but it's quick and easy and would quickly narrow it down.

... and Tiptronics, as stated by Boxsterra need to be in "PARK"or "Neutral" in order to start.
There have been issues with the shifter's selector switch (996.613.023.00).
Happy Boxstering,
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

---

Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

If my car doesn't start on the first try, because I stop cranking too soon or my foot moves on the clutch pedal or whatever, I have to turn the ignition switch all the way back to off before it will crank again. So my question is, where is that interlock? In the ignition switch, the DME, or??? Sounds like that could be the problem.

Al

No, I only have 1 key. After all of this, I will go to the Porsche dealer and get extra keys.

No remote entry or it doesn't work? Sorry I wasn't clearer... I did see that you said the immobolizer was "dry," but if the you DO have remote entry and that it DOESN'T work...it might point to a problem with that. A reach, but you have already looked at the "low hanging fruits" :-) So I thought I would chime in with something even if it seems unlikely.

I have no remote. I have one key the I use for ignition as well as locking and unlocking doors. I am still having problems understanding why the car will start if I disconnect the battery for 5 to 10 seconds and then reconnect it. The car will start one time only. I can repeat the procedure and get the same results.. If the Immobilizer was bad, I do not think it would start at all. I believe that it could be related to the Immobilizer in that the DME relay is not receiving the correct signal, and I believe that the signal must originate at the Immobilizer. I am going to continue to check further. Thanks for the help.