66corsaguy wrote:Fri Sep 01, 2017 5:22 pm
It used to crank a little but now nothing. I have a new wire for starter coming. I re wires the yellow wire to the starter temporarily
When I try to start lights go dead for a second. Accesory lights are fine. I checked fuse. It's fine.
What the heck?
I have read through the previous comments, but I have not seen any pictures of your engine compartment and have not seen any comments concerning the ground connections for your battery. Assuming that the battery does not have any dead or shorted cells and is holding a charge and is capable of delivering the amperage needed to power the starter motor, I'm troubled by your comment about the lights going dead for a second.
As shown in the schematic wiring diagram for the Corvair below, as well as in some of the photographs, a properly grounded electrical system in a Corvair requires two connections. The ground connection that supports the starter motor must be a heavy, thick gauge cable that is the equivalent of the positive cable in current carrying capacity. The thick positive cable is connected directly to the starter motor. Its only job is to provide current to the starter motor while the engine is being cranked. Essentially all of the remaining electrical needs of the Corvair are provided through the thin 12gauge wire that also travels from the positive battery terminal to the Corvair — in this case to provide voltage to essentially every other electrical circuit in the car. In an automotive electrical system, all the electrical support that is seen from the positive terminal of the battery must have an equivalent on the negative terminal. In other words, there should be a thick ground cable that is connected directly to the engine (not to the car chassis). The starter motor draws more current than any other device in the car. It must have an equivalent return path for that current that connects to the negative side of the battery. The engine and transaxle are physically isolated from the car chassis by three rubber motor mounts. These mounts are designed to isolate much of the engine vibration from the car, but at the same time they also electrically isolate the engine from the chassis. Because of this, a ground connection from the battery negative terminal to the car chassis would not provide an adequate ground return path from the starter motor to the negative terminal of the battery. A heavy 6gauge positive cable delivers current to the starter motor, and an equivalent 6gauge negative cable must return from the engine to the battery negative terminal.
In the wiring diagram you will see a red 12gauge wire that is tied to a distribution point and then moves on to the charging system and remaining car electrical wiring harness. This wire delivers current to all the accessories, headlights, electrical fan, windshield wipers, turn signals, etc. The ground return for all of these devices is the car chassis itself. In the wiring schematic you will notice a 12gauge black wire that is connected to the car chassis, and a 6gauge thick cable that is connected to the engine. Both grounds are essential for proper operation of the car electrical systems. The fact that you mentioned that the lights dim when you engage the starter may be an indication of an inadequate current carrying capacity in your wiring harness and grounding system. Please inspect your battery connections to see if they match the wiring requirements shown in the wiring schematic. If you find the ground cable bolted to the chassis and no additional connection to the engine, this could be the cause of your starter failure. (I am assuming that when you state that your car will not start, you are actually saying that the engine will not crank when the starter is engaged. The engine failing to start normally means that you are cranking the engine, but it refuses to start. When trying to diagnose an electrical problem over the Internet, we need to know if your problem is the engine failing to turn when the starter is engaged, or if the engine fails to start, even when the starter motor is correctly doing its job).
To see the full schematic diagram...
viewtopic.php?f=225&t=12968
As mentioned earlier, the yellow wire that connects to the starter solenoid has nothing to do with the starter motor or starter solenoid's ability to crank the engine when the ignition key is turned to START. The yellow wire only provides 12 V DC to the ignition coil positive terminal for the period of time that the engine is being cranked. This has the effect of boosting the coil output to the spark plugs to promote starting while the engine is being cranked.
The purple wire shown in the illustration below is the one that connects directly to your ignition switch in the dashboard. When you rotate the key to START, 12 V DC is applied to the starter solenoid via the purple wire. This voltage triggers the solenoid so that it physically moves the starter mechanism to engage with a large ring gear on the clutch assembly or torque converter. At the same time, heavy duty contacts inside the starter solenoid complete the circuit between the 6gauge positive battery cable and the starter motor itself. In this way the starter motor receives its current through a special heavy duty switch that is inside the starter solenoid. The ignition switch in the dashboard actually handles very little electrical current. It only provides a small current via the purple wire that triggers the starter solenoid. The solenoid itself handles the heavy current needed by the starter motor. (If you were to utilize a remote starter switch to trigger the solenoid, you would clip one lead to the cable that connects directly to the battery positive terminal. The other lead of the remote starter switch would be clipped to the solenoid terminal labeled "S", which is the same terminal that is already connected to the purple wire. Pushing the button on the remote starter switch establishes a connection between the battery and the "S" terminal, which triggers the starter solenoid. This bypasses the entire wiring harness and the ignition switch in the dashboard. It is a method used to trigger the starter motor directly from the engine compartment location. It is also a method you can use to bypass the wiring harness between the dashboard and the starter motor, which would help you to determine if you had an ignition switch/wiring harness problem or starter problem).
- 1965-1969 Corvair Engine Compartment Wiring Harness Starter Connections.jpg (80.88 KiB) Viewed 3396 times
The 12-pin multiconnector in the engine compartment is sometimes a point of electrical disruption. With the exception of some cylinder head temperature sensor(s), almost everything passes through that multiconnector. Since it is aging, and physically located within the engine compartment (below the voltage regulator, near the firewall), it is exposed to moisture, heat and vibration. The metal contacts inside the plastic connector shell can become corroded, loose, bent, etc. So it might be helpful to carefully separate the two halves and inspect the condition of the pins inside. Sometimes simply unplugging and reconnecting the two halves will clear the problem, as re-seating all of those connections may reestablish a previously marginal electrical contact. If you want to attempt any cleaning with a wire brush, chemical contact cleaner, etc. you should disconnect the battery ground terminal to avoid creating any undesired electrical shorts.
If you suspect a battery problem, he could try substituting an alternate battery (if available), or take your existing battery to an auto parts store, Sears, etc. to have it load tested. This sometimes identifies faulty batteries that have dead cells or an internal short that prevents it from delivering the current needed to crank the engine.
Sometimes dirty battery terminals will cause just enough isolation between the battery cable and the battery terminal to prevent current flow to the starter motor. A wire brush like the one below should be used to clean the battery terminals and the inside of the battery cable connectors to ensure a clean connection on both the positive and negative terminals.