I'm driving home today and the starter kicks in. Ugly sound. Glad I wasn't on the freeway. Turned the motor off and coasted to the shoulder. If I turn the motor over and it doesn't start, everything acts as it should. If the motor starts, the starter stays engaged.
I'm off to google some solutions. Any ideas from the gallery appreciated.
'83 245 automatic. Bazillion miles. Original crumbly engine harness...
Sounds like the ignition switch (the electrical part) is falling apart inside. Or, it's your "crumbly engine harness" shorting wires together.
If you can get at the starter, disconnect the small "push-on" wire, hook it to a test light or voltmeter, and make sure it ONLY has voltage when the key in the "Start" position. It should be dead in any other position. Try it several times, bang on the steering column, shake and twist the harnesses, etc...
Well the obvious place to start is replacing or rebuilding the engine wiring harness. That's almost certainly the cause. It's shocking that the car still runs at all with the original harness.
For sure the harness needs to be (will be) replaced. I milked it way too long as it is. Won't be able to get to it for two weeks though. Barton is pretty much out of stock on replacement stuff. Maybe we can piece together enough bits so I don't have to run every wire. Until then, I need to figure which wires to mess with to get it running (without the starter turning)
Don't think it's the switch. the starter behaves as it should as long as the motor doesn't start. Only when it starts, the starter continues to spin engaged. James is right. The harness is the likely culprit. Now to figure which wires to replace...
Ability is not an issue... I've been wrenching all my life. Not as much fun as it used to be though. *g* The challenge will be finding enough good wire to work with. All the wires from the connector at the firewall was bare when I got the car. I sealed the wires with liquid electrical tape. Fairly sure the wires will crumble when I remove the harness. Making a new harness is straight forward. Salvaging the connector(s) may not be so easy.
I've rebuilt several harnesses from scratch, it's a lot cheaper than a new one. You'll need a bunch of wire, heatshrink tubing and electrical tape, as well as a soldering iron, rosin core solder and a heat gun. Best way is to remove the harness, lay it out on the ground or a sheet of cardboard or something, and tape it so it stays put. Cut off the outer sheath and then cut pieces of new wire of the correct size from spools and lay them out. Solder joints where required and cover with heatshrink, then slip heatshrink over the large sections of the new harness to protect and contain the wires. Snip the connectors off the old harness one at a time and splice them onto the ends of the new harness by soldering and heatshrink over those too. Usually the big connector to the ECU has a couple feet of good wire on it that is inside the passenger compartment, I like to stagger the joints here to reduce the chance of a sharp bit poking through the heatshrink and shorting. It should also be mentioned that you do NOT want to cut the wires to the knock sensor and O2 sensor connector, they are shielded coaxial cables.
Don't try to patch up and keep going on what you've got, it's just asking for a fried ECU, as well as it's dangerous, your car could stall while pulling out into traffic or have an engine compartment fire which can quickly spread to the entire car.
Salvaging the connectors is not hard, just snip them off with about an inch of wire remaining, strip off the insulation, slip a small piece of heatshrink over the new wire, strip about an inch and twist them tightly together then solder.
Often the old wire will be heavily oxidized in which case I've used some fine sandpaper to scrub the strands of old wire until enough clean copper is visible to make a nice tight soldered connection.
The larger connectors at the firewall are nice because the pins can be individually removed, I sometimes snip connectors from damaged harnesses at junkyards so I have spare bits for this sort of thing.
About what I figured... Thanks for the tip on the O² and knock sensor wires.
16, 18, or 20 ga wire? Do you mess with color coding or just run a bunch of the same color wires?
Good idea. A trip to the pick a part is in order to get some spare connectors, pins, and stuff. fun... fun...
IIRC there's a few #10, some #16 and some #18. I use a variety of colors, I haven't found a good place to get wire in the variety of striped colors the original harnesses use so I try to pick a color that's close and stick to it for that purpose. Makes it a whole lot easier to keep track of and troubleshoot.
Another thing worth mentioning is make careful note of which connector goes to the throttle switch and the idle speed motor, I found out the hard way they're interchangeable, and at least on a 740 if you get them swapped it blows the transistor in the ECU that drives the idle valve.
Big wires then. I wouldn't have guessed, looking at what's hanging out of the firewall plug. Troubleshoot? If it doesn't run when I finish, it's off to the boneyard with it! ... not really. *g*
Good to know, thanks!
Some of them may be smaller, for the sensors and such, but #18 is common and cheap, no reason to go smaller.
Agreed. Wire is cheap. Just don't want to end up with a harness that's too fat to bend.
12 ga is ~1/8" in diameter. Doesn't take too many of those before the harness becomes a python. Anyway... I have several links to look at with pictures and info on doing harnesses. Should be no problem getting it sorted.
There's only a couple of big fat ones, and they're all stranded, I never had any trouble with flexibility and I use heatshrink since it's easy to find big pieces of that in all different diameters and I was never able to find a source for the sheathing they use from the factory, so the harness ends up thinner than original.
How much (if any) of the wiring has to be accessed from under the car? I'm debating putting the car up on ramps before I start... much easier to do while it's still running. Sure, I could jack it up later and put it on stands if I have to.
Just the wire for the oil pressure switch and/or sender and the wires to the alternator. Most of the work you can do from up above, and that will be much easier with the car on the ground. I suppose you could put it up on ramps, disconnect that wiring, then lower it down. You could start the car with that stuff disconnected so long as you insulate the big red wire since it goes straight to the battery. 700 series is easier since the alternator is in a different spot so only the oil pressure wire goes down under the front.
You'll probably want a new gasket for the intake manifold so you can pull that off. With that out of the way it's much easier to work with the old brittle harness and it's a good excuse to thoroughly scrub out the throttle body and all the vacuum nipples. One other tip, anywhere I use crimp connectors I solder them too and put heatshrink over the connection, helps prevent corrosion from ever lurking.
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