Starter problem

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Dlbarnes1962
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Joined: Tue Jun 13, 2017 11:35 am

Starter problem

Unread post by Dlbarnes1962 » Thu Nov 09, 2017 5:11 am

Starter would"jump start" off solenoid... Changed solenoid and started with key twice ....and now ..nothing...dash lights all seem to work with key on, but again i have to jump start off solenoid with screwdriver to start car again?

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bbodie52
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Re: Starter problem

Unread post by bbodie52 » Thu Nov 09, 2017 6:27 am

Your car is a 1968 Corvair Monza?
Dlbarnes1962 wrote:Thu Nov 09, 2017 7:11 am

Starter would"jump start" off solenoid... Changed solenoid and started with key twice ....and now ..nothing...dash lights all seem to work with key on, but again i have to jump start off solenoid with screwdriver to start car again?
In stating that you "jump start off solenoid with screwdriver" I'm assuming that you are using a screwdriver to create a short between the solenoid "S" terminal (purple wire) and the main battery cable terminal, to apply battery voltage directly to the "S" terminal to energize the solenoid. But when you try to use the ignition key switch to energize the solenoid your success rate is intermittent at best.

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In using a screwdriver to apply voltage to the solenoid "S" terminal you are creating a temporary bypass circuit that would be the same as using a remote starter switch that would be attached to the solenoid terminals.
Remote Starter Switch.jpg
If this works reliably every time, but the purple wire ignition switch circuit has proven unreliable, your original problem may not have been a bad solenoid, but a voltage drop (intermittent circuit with high resistance) between the ignition switch and the solenoid, or the ignition switch internal contacts could possibly be faulty. The fact that the wire between the ignition switch and the solenoid "S" terminal is a relatively thick 12 gauge wire tells us that the current needed to actuate the starter solenoid is fairly large. This means that a large resistance in that circuit — possibly caused by corroded or burned contacts — could reduce the current flow available to the solenoid from the ignition switch to a level that is too low to activate the solenoid. A temporary bypass using a remote starter switch (or a screwdriver) would restore the needed current to trigger the starter solenoid.

To help you visualize the starter circuit, the entire circuit can be traced from the starter solenoid to the ignition switch using the diagram below.
Left-click the image to enlarge it for better viewing or "Pan & Scan"...
1965 Corvair Monza Full Schematic.jpg
1965 Corvair Monza Full Schematic
:link: viewtopic.php?f=225&t=12968

As shown in the illustration and close-up engine compartment schematic below, the purple wire (12 PPL) that is attached to the solenoid is ultimately connected at the other end to the ignition key switch. Along that path there is one two-pin plastic connector and 2 12-pin electrical multi-connectors that the circuit must pass through. (with Powerglide automatic transmission equipped Corvairs, there is also a NEUTRAL SAFETY SWITCH added to the circuit at the shift lever). The final electrical connector is the one that connects directly to the ignition switch. Although the 12gauge wire itself could be faulty at some point along this path, it is more common to have an electrical problem within one of the multi-connectors. The multi-connector shown in the illustration below the voltage regulator in the engine compartment is often the cause of problems. More than 50 years of age and exposure to heat, moisture, and vibration can cause corrosion and high resistance to develop between the metal pins that are encased inside the 12 pin plastic housing. Each of these plastic connectors creates a possibility of a poor connection inside that can disrupt an electrical circuit. Isolating the exact cause of an electrical malfunction requires a little trial and error testing. I would suggest that you work your way along the circuit starting in the engine compartment near the starter. You can unplug the two wire connector near the solenoid in the engine compartment and examine the metal pins inside to make sure that they are clean, not corroded, and form a tight electrical connection when the two halves of the connector are joined together. A similar procedure should be done with the 12 pin multi-connector. (If you are going to clean the metal terminals within the connector, be careful not to create an electrical short. It is usually wise to disconnect the battery negative terminal to eliminate the possibility of an electrical short while you probe and clean inside the plastic connector).

After cleaning and examining the two connectors in the engine compartment, you should test and operate the starter motor again using the ignition key to see if the problem has been eliminated. It may not be necessary to proceed any further in testing the circuit forward of the engine compartment. If the problem still exists you will have to move to the other end and work under the instrument panel and dashboard. There is another 12 pin connector in the wiring harness at that end plus the connector that plugs into the back of the ignition switch. A corroded or damaged electrical connector is possible at either point. If all of the connectors appear to be good you can actually test the circuit by creating a jumper between the red voltage wire and the purple starter solenoid wire while the connector is unplugged from the ignition switch. This is similar to the testing you were doing at the starter solenoid by creating a jumper between the battery cable and the "S" terminal on the solenoid. If the circuit tests good through the entire harness, but fails to work reliably when reconnected to the ignition switch, you would have to assume that the internal contacts inside the ignition switch are likely faulty. At that point you would probably end up replacing the ignition switch.
1965-1969 Corvair Engine Compartment Wiring Harness Multi-pin Connector.jpg
1965-1969 Corvair Engine Compartment Wiring Harness Multi-pin Connector
1965-1969 Corvair Engine Compartment Wiring Harness Multi-pin Connector.jpg (33.79 KiB) Viewed 89 times
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:link: http://www.corvair.com/user-cgi/catalog ... IN&page=89

Part number C2430: 68-69 IGNITION SWITCH (LESS KEY CYL)

Weight: 0 lbs 8 oz
Catalog Pages(s): 89
Price: $ 29.30

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It is also important to have the engine properly grounded (so that the starter motor assembly is properly grounded with a ground return that is equal to the heavy gauge positive cable from the battery). As shown in the illustration below, the thick negative battery cable should be bolted directly to the engine. The thinner 12gauge wire from the negative battery terminal is normally attached to the car chassis. The rubber engine mounts tend to isolate the Corvair both from vibration and electrically. To ensure a proper ground return for the charging system and starter system a direct cable connection between the battery and the engine is needed.
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:chevy:
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible

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