are all ballasts equal? for my 68, it has the normal one bolted to the firewall and one on the wiper motor....are they the same??
I noticed the bases are different, the holes are in different locations. is it just the matter of using the right bracket or are these differerent risisters altogether??
regardless.....the one mounted on the wiper motor(2-speed)...is it different than the other ballast resistor or the same was the intent of the question...?
The resistor used on Chrysler 2-speed car wiper motors from 1968 through ~1976 (into the 1980s for some applications), part number 2822261, is similar, but not the same as ignition ballast resistors. The wiper motor torque limiting resistor, 2822261, typically ranges 0.25-0.5 ohms in resistance. It is an open back, ceramic power resistor. The resistor limits current and results in a lower applied voltage to the motor for low speed operation.
The Chrysler ignition ballast resistor used in the 1960s through 1972 for point systems, part numbers 2095501, 2196316, or 2275590, is also an open back, ceramic power resistor. This ballast resistor measures 0.5 ohms and has specific, expected thermal design properties.
The ignition ballast resistor could replace the wiper motor resistor and function, but the motor might run a little slower on low speed.
The wiper motor resistor could functionally interchange with the ignition ballast resistor, but it could overdrive the coil and points, and may not behave the same thermally as the ignition ballast resistor.
Following, I have written some simplified operation information about ballast resistors in Chrysler ignition systems of the 1960s through the 1980s (excluding Electronic Lean Burn and Electronic Spark Advance/Control systems which did not have a ballast resistor). FYI...
With the point systems' primary circuit, the ballast resistor's resistance varies directly with temperature, and indirectly with engine RPM to maintain a stable voltage at the ignition coil, and subsequent current through it. When the engine is started, the ballast is bypassed. When the engine begins to run, and the ignition switch returns to "Ignition Run", the ballast is initially cool and resistance is low. As the engine runs at low speeds with longer induction build and collapse times in the coil, the ballast heats up, resistance increases, and current through the coil and voltage applied drops, preventing coil overheating and reducing point arcing. At higher engine speeds, with lessened induction build and collapse times in the coil, the ballast cools, resistance lowers again, and more current and applied voltage for the coil is available for higher speed secondary circuit spark plug firing.
Chrysler electronic ignition, which first appeared in late 1971 340 with manual transmission models, introduced the four-pin ballast resistor, part number 3656199. The primary, or compensating, side of this dual resistor is still the same as the earlier point systems with an open back ceramic housed wire wound 0.5 ohm resistor. It still performed the same thermal adjusted coil current/voltage stabilization. It also limited the current through the power transistor of the Electronic Control Unit (ECU), protecting it. The other side of the ceramic case housed an enclosed "non-thermal" 5 ohm auxiliary resistor. This 5 ohm resistor is connected to the "fifth pin" of the ECU. Later, in 1975, Chrysler adjusted the primary resistance in the four-pin resistors to 1.25-1.5 ohms and also encased the resistor reducing the thermal action (part number 3874767). Although all performed the same basic function, there were multiple versions of the ECUs depending on application. In general, the aftermarket produced a single ECU to cover all applications.
In 1980, Chrysler revised the ECUs to remove the external auxiliary resistor connected to the fifth pin of the ECU. This was the "four pin" ECU. The new two pin ballast resistor (part number 4106340, 5206436, et.al.) was 1.5 ohms for the primary circuit to the coil. This is why a four pin ECU can be used in a five pin ECU system with its four pin ballast resistor. The old 5 ohm resistor half is not used, nor connected internally (if a "dummy" fifth pin is in place). However, an early five pin ECU cannot function in a system with a two pin ballast because there is no circuit to connect to the "real" fifth pin.
The 1.5 ohm ballast should not be used in place of a 0.5 ohm ballast. It will function in most cases, but coil energy will be reduced. The later four pin ballast will function okay in place of the earlier four pin ballast, but depending on the ECU, optimal coil energy might be reduced.
Direct Connection/Mopar Performance ECUs typically require a primary ballast resistance from 0.25 ohms to 0.7 ohms depending on the ECU version and coil. Aftermarket high performance coils and ECUs vary in ballast requirements. Aftermarket replacement ECUs vary depending on manufacturer plus coil and/or ballast requirements and ratings vary per manufacturer but often cover a broad range of applications functionally, although not necessarily ideally.
NOTE: When measuring low resistances such as ballast resistors, account for the resistance of the test leads connected to the measuring device. This can be done by shorting the leads together, noting the resistance, and subtracting it from the measurement readings, or use the meter's relative setting (if equipped) similarly with the lead shorting, or use a meter that measures conductance and convert accordingly, or use a four wire ohms measurement setup with the appropriate device.
