No-start - suspect bad ignition switch or bad solenoid, have questions

[Otter74]

I’m on a trip and my SC failed to start this afternoon. Got a half-second crank then nothing after that. Came out of nowhere, so no symptoms beforehand that I had a potential issue. In nine years the car has never failed to start.

Car has all the electrical power it needs, and won’t start from a jumper pack either. No click from the starter solenoid so conclusion is either a sticking/bad solenoid or a bad switch. I suspect the switch. Can’t really access starter to whack solenoid to see if it unsticks without borrowing a jack and taking the wheel off but will try if I can.

I have the Haynes manual with me. But looking at the switch from under the dash, can someone tell me which wire is what? I do have a power probe so if I can give the starter 12V I can determine whether it’s the starter or upstream from that. Not very practical to probe at starter unless I can jack it up. Convenient spot on chassis harness to send 12V to starter solenoid? All fuses OK.

Car bump starts fíne, so we push started it where it died after turning it around, and again after dinner. I can probably roll start it out of my parking spot at my hotel but would love to be able to figure this out by bedtime Sunday.

[Otter74]

It did occur to me that the ignition tumbler is worn enough that it isn’t engaging switch.

What’s an easy place to hot wire the starter? This is preferred for three days between now and getting home over trying to roll start it every time

[PeteKz]

Since you're on a trip, without lift or jack stands, you will have to test for voltage at the points you can access. Do you have a volt-ohm meter or a test light? If not, find your closest Harbor Freight or big box store and buy one.

I would first check for 12 volts at the yellow wire at the 14-pin connector on the back of the relay board. Pull the connector apart and check at Pin#1. When you twist the key to start, you should get 12 volts. If you don't, go back to the ignition switch and look for the heavy yellow wire, then test for 12v there. If you do get 12v at Pin#1, then you will need to figure out some way to get under the car to test for 12v at the spade terminal on the starter solenoid where the yellow wire plugs in.

If you're going to insert a hot wire to the starter, Pin#1 is where I would do it, and I would take 12v from the positive side of the 3-fuse block on the relay board.

I don't understand your last message, please explain what you mean by the tumbler isn't engaging switch. You are able to insert the key. and turn it to "ON", right?

[Otter74]

Thanks - I’ll try that. I’ve got a DMM and a power probe with me. Occurred to me to ask relay board in frunk or in engine compartment? I don’t believe there is an ignition relay, is there?

Car is running a Megasquirt but I’m not sure that matters. First thing I did was get my laptop out but of course despite my plugging it in to charge before leaving for trip, it isn’t charged and I can’t use it.

By last message I meant is it possible the start position isn’t being engaged when I turn key from ON to START.

I can find someone with a jack and I have tools, it’s just a matter of people having time. Fortunately there are other 911 people around

[Otter74]

Confirmed start position is activating at switch - at least I see power dim slightly when key goes to start

[Otter74]

Good news (Twix!) - sticky solenoid. Borrowed a floor Jack and put it on a stand and took the wheel off, hit it a few times, still didn’t start, I was testing for 12V whole a friend turned key after he hit it again and it turned over. Starts fine for now. Someone else had a spare ignition switch on case I needed one

Can a sticky solenoid be cleaned? I’ve never had to deal with one.

[rowingone]

I would replace the solenoid but yes they can be cleaned . . disassemble and clean any residue off the copper brushes . . if the brushes are not too badly worn it will operate as intended once cleaned.

[mysocal911]

Another no-crank thread, more lately!

[917_Langheck]

When you get back home, you will need to remove the starter to r&r the solenoid, so stick in a new high torque starter in its place while you're in there, and rebuild the Bosch at your leisure.

There is a thread, with video, on how to disassemble the solenoid - which has no brushes to worry about, that's on the starter with the armature.

In addition to adding a new starter, you remove about 7lbs of mass off the back of the car!

Good luck on your trip, and always back into an uphill parking spot (BTDT).

[Otter74]

Originally Posted by 917_Langheck

When you get back home, you will need to remove the starter to r&r the solenoid, so stick in a new high torque starter in its place while you're in there, and rebuild the Bosch at your leisure.

There is a thread, with video, on how to disassemble the solenoid - which has no brushes to worry about, that's on the starter with the armature.

In addition to adding a new starter, you remove about 7lbs of mass off the back of the car!

Good luck on your trip, and always back into an uphill parking spot (BTDT).

Ha! That’s what I did at the hotel last night but wasn’t enough to get me roll started. Back to having fun!

[proporsche]

just make sure you check your ground between the the transmission and body....
Ivan

here
83 911 - Loss of all power when key is turned to crank engine

[blucille]

Lots of threads on this subject.

I know a lot of theories out there. There are very few failures of things like the electrical portion of the ignition switch, transmission ground strap. But. These starters/solenoids fail on rallies. Especially hot weather like today. You need a new starter. That’s it. Yes. Hit it with a hammer you might get a few more starts out of it.

Seek out the lightweight WOSP gear reduction starter and you will never have this problem again. And you’ll save 20 lbs. and hundreds of dollars. Bosch rebuilts will fail again, maybe within the first few days/weeks/miles

Our host will give you a lifetime warranty.

[Otter74]

Originally Posted by proporsche

just make sure you check your ground between the the transmission and body....
Ivan

here
83 911 - Loss of all power when key is turned to crank engine

Good idea - will check this at home. When I was under the car this morning I was using the brake rotor hub as a ground and getting just under 12V until it suddenly turned over but I did not thing to compare to using trans case for ground

Originally Posted by blucille

Lots of threads on this subject.

I know a lot of theories out there. There are very few failures of things like the electrical portion of the ignition switch, transmission ground strap. But. These starters/solenoids fail on rallies. Especially hot weather like today. You need a new starter. That’s it. Yes. Hit it with a hammer you might get a few more starts out of it.

Seek out the lightweight WOSP gear reduction starter and you will never have this problem again. And you’ll save 20 lbs. and hundreds of dollars. Bosch rebuilts will fail again, maybe within the first few days/weeks/miles

Our host will give you a lifetime warranty.

Am definitely doing this after I get home