If I wired the alternator wrong, should the engine still turn over?

[Christien]

A routine outer pulley half replacement has turned into a massive PITA, and my brain is at the point now where I'm so damn frustrated I can't think clearly.

I had to replace the pulley half because it had been improperly seated and over time started to wobble, to the point where the fan was rubbing the surround. I pulled the fan/alternator out at the same time to inspect the alternator and make sure the shaft wasn't damaged (it wasn't). The new pulley half came and today I started to put it all back together. I got so far as to turn the engine over to properly seat the fan belt on the pulley but the engine was dead. I'm getting electrical - alt light, heater fan, radio, fuel pump, but absolutely nothing when I crank it, nothing from the starter motor, nothing from the engine. I drove it into the garage, so I know it was working when I parked it a few days ago. Battery is fine.

I always take a pic of the alternator wiring before disconnecting it, so I'm 99.99% sure I wired it up right, but I thought I'd ask cooler heads here before tearing it all apart again. I hate removing the alternator. Especially unnecessarily.

[AVDCAV]

You know the drill " walk away tomorrow is another day .
Just something simple. Just pull it back off and start over .

[john walker's workshop]

see if the yellow wire came off the starter solenoid.

[Christien]

Could it come loose/off with the car just sitting?

[304065]

Best case: yellow wire fell off the solenoid. Reattach yellow wire.

Worst case. You connected B+ to D- and D- to B+. In a nanosecond, you burned up the alternator diodes.

Where is this photo of the back of the alternator?

Scratch that. What happens when you turn the key to the "Run," not "start" position?

[T77911S]

Check the battery connections.

Did u remove the conne tor on the relay panel? The start signal runs thru it.

[Christien]

Originally Posted by 304065

Best case: yellow wire fell off the solenoid. Reattach yellow wire.

Worst case. You connected B+ to D- and D- to B+. In a nanosecond, you burned up the alternator diodes.

Where is this photo of the back of the alternator?

Scratch that. What happens when you turn the key to the "Run," not "start" position?

At run position I get alt. light, radio, heater fan, fuel pump. Here's the pic:

Originally Posted by T77911S

Check the battery connections.

Did u remove the conne tor on the relay panel? The start signal runs thru it.

The only thing I disconnected was the positive lead to the battery.

[coldstart]

Chris, I have the same/similar picture from removing my alternator. Great minds think alike!

[Christien]

Pulled it all apart, alternator is wired correctly, exactly the same as it was when I pulled it apart.

But back to my original question, if it's wired wrong the engine should still turn over, should it not?

[Bob Kontak]

Believe the answer is yes. The alternator is downstream of the starter.

Have you tried any of the suggestions from above, like the yellow wire?

I know you did not have the starter off but silly stuff can happen to good people.

Edit: After reading again I see the only thing you did in the front was the battery cable. Go back to that area and look for something odd.

Whack the solenoid, maybe?

[Christien]

I did check all around the battery, everything looks normal. I'll get underneath later today and check the starter. It makes absolutely no sense whatsoever, but I've been in that situation before, and I know sometimes write things happen which are completely unrelated, just bizarre coincidence.

[al lkosmal]

As you removed and re-installed the alternator, you were moving the wiring harness. The positive lead on the alternator runs to the starter and is connected to the positive terminal, which is in close proximity to the yellow wire/terminal on the starter.........so it is possible that the yellow wire was pulled off, while you were playing with the harness.

Anyway, it is easy to check and very easy to fix....so why not start there.

regards,
Al

[304065]

Christien,

I can't really see the wire colors but it looks OK. Remember:

Brown D- ground
Brown ground strap from fan housing to engine case
B+ to battery (two reds)
D+/61 blue wire
DF dynamo field black wire.

Probably what you did is pull too much on the red wire, which runs from B+ down to the starter through a rubber grommet on the right front portion of the shroud. When you did that, you may have disturbed the yellow wire on the starter.

Be extremely careful jacking and supporting the car, bring a flashlight and prepare to get VERY greasy under there. Also make sure you have the battery disconnected, you can easily kill yourself by touching the stud on the starter cable.

[Bob Kontak]

I just looked at the 1971 wiring diagram in the tech info center. The yellow starter wire does route thru the 14 pin connector on it's way to the solenoid. As mentioned, if you reefed some on the wire clusters that may have stressed some of the connections (at that connector).

I betcha the yellow wire is the culprit - somewhere in the chain.

[86 911 Targa]

Originally Posted by Bob Kontak

I just looked at the 1971 wiring diagram in the tech info center. The yellow starter wire does route thru the 14 pin connector on it's way to the solenoid. As mentioned, if you reefed some on the wire clusters that may have stressed some of the connections (at that connector).

I betcha the yellow wire is the culprit - somewhere in the chain.

I agree, I sent him the circuit, he probably pulled on the connector.

This is for our '86, but looks similar:

[1990C4S]

PM me if you're really stuck. I think I'm in Hamilton Saturday anyway....

[DRACO A5OG]

Man we are a GREAT BAND of BROTHERS

+1 may have pulled on the yellow wire.

[al lkosmal]

Check the yellow wire at the starter connection too.

regards,
Al

[Christien]

I got under the car and checked out the starter - the connections there are all good. I can't see any loose connections anywhere in the engine bay.

[al lkosmal]

Ok.....the next easy thing to check is the ground integrity to the starter, by checking the ground strap that connects the tranny to the engine. I know it's a long shot, but I have had this happen on two of my 911's. I.E. one day works great, sit for a while and the next time I go to start...nothing. You can remove it and clean the end connection points on the strap, as well as the grounding points that it connects to on the tranny and the engine. ....but here's the way I check it 1st. I hook my jumper cables together to make one long jumper and clip one end to the ground post that the battery minus is connected to and the other end I clip to the starter mounting flange or as close as I can get to it. This provides a straight ground path to the starter and if your car starts up....you know that you have a grounding issue, which is usually the ground strap being corroded, dirty...etc.

Make sure the you do this carefully and don't accidentally allow the cables to touch power etc. I.E. do this carefully and at your own risk (small print)


regards,
Al