Wiring Help Please, 87 924S

[jjeffries]

Good Morning All,

I'm only writing this after a lot of web-searching, trying to decipher factory wiring diagrams and investigation with flashlights and mirror. I wish I were smart enough not to have to ask!

Current situation, no pun intended, in two parts:
(i) car will not crank
(ii) other harness connections

1. I have my car re-assembled and ready to attempt its first post-rebuild start. I have had this car far apart, by necessity.
1a. Ignition switch, mechanical and electrical portions, reference sensors, Fuel Pump Relay and fuel pump are new. New 91-Group battery.
1b. Car came to me having been dead for twelve years.
1c. Car came to me with fuel pump hot wired; I have removed that wiring.
1d. I cleaned all grounds (I believe "all") when re-assembling the car.
1e. I've had the dash out for refinishing, was careful with my labeling, but now have some connectors I either didn't label or the tags fell off, and are causing me some confusion.
1f. I've cleaned all the fuse holders and fuses themselves.
1g. This car does not have a factory alarm (or aftermarket alarm) and does not have Tempostat/cruise control

2. I tried to start and got no crank. Battery and Oil Pressure lights are on. Oil Pressure light will pulsate slightly, almost like a turn signal rhythm.
3. Using a remote start switch (a KD Tool, just a switch with alligator clips) will result in the solenoid activating, but will not crank the engine over. This test also causes the fuel pump to run. Yes, I've had the starter motor apart, installed a new solenoid due to the original cracking.
4. Putting a simple test light on the Red/Black two-wire connector in front of the brake booster (this, I believe, sends the 12V from the ignition switch to the starter solenoid) and turning the key to Start yields nothing.
5.The same test will, however, illuminate the test light on the smaller, blue wire (alternator exciter).

6. When trying to crank it over, and still now, I did not have the interior center console installed (interior is all out), but I did plug in the center gauge pack (to monitor oil pressure). Why not fully assembled? My goal is to get the car running, then work on the interior.
7. While I realize, and have seen it written, that the Starter Circuit is a simple one, I figured getting the all car's connections connected would be prudent.
8. You'll see in the photo below that, at least, the stereo end wiring the wiring harness has been botched. Yes, I will insulate those before turning on the ignition.
9. This car/these cars were built with a somewhat universal wiring harness; there are many connectors that are not used in this, a bare-bones, USA-spec, manual 924S.
10. Meaning, the task at hand isn't as easy as making sure "everything is plugged in" as a means of being sure I have things in the correct configuration.
11. In the wiring bundle with the center console's various connections is the female side of a 14 pin connector, just as is used for the primary engine connection in my 82 911SC. I've did not appear to have labeled this, nor can I locate its male partner. Is this 14 pin connector active in an 87 924S?

I realize there are many (too many) variables described here. I have printed out all the factory WSM wiring charts; I cannot find that 14 pin connector anywhere, but the way the diagrams identify harness connectors is still not fully clear to me; if there's a legend page, I haven't found it yet. (Twenty six years ago I had the Haynes 944 manual, but ten years ago I gave it away!).

Any help/guidance appreciated. If my questions aren't clear, let me know and I'll do my best to work through whatever you may need to know to help increase my own understanding.

Thanks in advance,
John

[SilverLined]

Puzzling about the no-start. Checking grounds and double checking fuses would be first on my list, but it sounds like you've done that.

Could that 14-pin be for your safety belt/brake warning light?

[jjeffries]

Silver, seat belt/ebrake display is a smaller connector in place.

Thanks for reading and thinking with me!

[jjeffries]

This was the view when I pulled the dash last winter:

John

[jjeffries]

Also adding to the "state of play", when I pulled the (original, seized) engine, I followed Clark's instructions and disconnected the main engine harness at the ECM, inside the cabin, and removed said harness with the engine. V2Rocket has since observed that's not the smart method, and indeed, re-installing it with the engine in recent weeks was a be-atch, even though I was careful.

John

[944 Ecology]

Starting at the beginning:

1) No crank... if you put a screwdriver between the large terminal and the smallest terminal on the solenoid, does it crank?

Yes, your battery, starter and wires to the starter are good.

No, check the above.

Report back for the next step.

[jjeffries]

George, good to see you here.

No, screwdriver test yields some momentary solenoid noise, activates fuel pump, but nothing more.

Two big gauge cables connected to the big post, Red/Black to the trigger, smaller one.

Connections are clean and tight.

John

[944 Ecology]

Bad starter?

Remove it and take it to Autozone, Advanced Auto, Pep Boys, etc. for bench testing.

[jjeffries]

Will pull and test starter next, report results. Thanks George.

[jjeffries]

Starter bench tests good, rotation and bendix drive. Both with external power and new battery (using jumper cables)

John

[jjeffries]

Showing ring gear and the two big and one small connectors to the starter, i.e., clean.

[jjeffries]

Put the starter back in, same thing. There's juice there but jumping terminals will only activate some solenoid noise and work the fuel pump, make sparks, nothing else. I did try loosening the starter as it bolts to the bellhousing (looking for a more comfortable fit?), no change (no $hit, $herlock!).

Photos of the grounds attached below.

Two thoughts, widely dispersed:
1. I didn't set the depth of the ring gear on the pressure plate correctly, so the relationship between flywheel cog and ring gear isn't allowing Bendix gear to move forward and engage?
2. My supply of 12V to the starter is OK but the ground path is inadequate? Tough to see how this could be.

Hopefully the answer is deffo not #1, maybe even not #2, but rather something else, obvious, that's eluding me.

Time to put on other clothes and do something different.

John

[16again2009]

I don't know if it is the fix but your battery ground is hooked up in the wrong place. It should be attached to the bell housing. It is grounded to the body, not the engine.

[16again2009]

Just looked at my 1988 924s. The wire I am referring to is the big black one with tape on it. Maybe that is not the ground. But my car has nothing bolted there. That looks like the a/c hose bracket.

[944 Ecology]

Originally Posted by 16again2009

I don't know if it is the fix but your battery ground is hooked up in the wrong place. It should be attached to the bell housing. It is grounded to the body, not the engine.

Yep, needs a good ground to the motor and bell housing.

[jjeffries]

Ok, big thanks gentlemen. I’ve used up all of today’s lower back budget so will resolve that in the morning. VERY much appreciated.

John

[jjeffries]

Progress report, and there has been some (progress):

Grounding the car properly has yielded a starter motor that does its thing
as designed with screwdriver test.

Trying to actuate the starter with the ignition key is still not working. With my wife working the ignition switch, there was voltage at the thick red/black wire to the starter solenoid, but it was really weak (dim bulb on test light; I then tried at again, this time with a meter, and there was nothing, with the meter or the test light.

Next I verified the red/black wire from the connector in front of the brake booster to the starter is good by adding 12V straight off the battery. That actuated the starter.

So it looks like I don't have juice coming out of the ignition switch. As mentioned previously, the ignition switch, mechanical and electrical sides, are new, Meyle-brand but inexpensive.

Would there be anything related to my as yet still mostly uninstalled center console and/or that 14 pin connector that could be creating this diminution of voltage? (I do have the console's gauges connected.) [Is that 14 pin connector even used in a base 924S?]

In the meantime, I'll pull the ignition switch and do some measuring there.

Big thanks to George, Always16, Rus, Jon and Jack for help so far.

John

[r-mm]

I would certainly think so. the first thing that comes to mind is that there is some ground within that 14 pin or associated wiring that is interfering with the circuits. I wish I could explain this in more exact terms but empirically I have found with every car I have worked on from the very simple - GTV too much more complicated - 964C4 -having just one ground disconnected or poorly connected can cause extremely confusing issues elsewhere. On the Alfa the tail light is integral grounded to the body but poorly so. tapping the brakes was causing unrelated lights to illuminate presumably as current sought a better path to ground. A dedicated ground solved this. On 964 I had a ground under the passenger seat removed for cleaning and attempted to do something unrelated maybe roll the windows up and a comically miss matched series of things (horn honk etc) happened - presumably as current went all wobbly.

[r-mm]

Does starter current flow thru the ignition or does this car have a relay ?

[jjeffries]

Ignition switch harness:

30 has power/is bringing power into the switch
Jumping 30 to 50 yields nothing.

Rus, no starter relay on this car.

John