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Another Example: LS2 Coils
The LS2 coil-near-plug coils are similar in form and function to the LS1 coils described above. This 'family' of coils includes:

• the LS2 coil (GM# 12573190, AC Delco D514-A) from the 2005-2006 Corvette (& GTO and Avalanche), and
• the GM coil used on 2002-2005 Cadillac Escalade, 2000-2006 Yukon, 1999-2006 Chevy Silverado, 2001-2005 Trail Blazer, and some Hummers, etc.. The model is GM# 10457730 or AC Delco D585 (also Wells C1251, Standard UF262, GM/Daewoo 190005218). The LS2/truck coil has a visible external aluminum heat sink near the connector.

These LS2 coils are incredible. Even compared to the LS1 coil, these are just crushers! On the LS1 coil there is around 40 milliamps of peak secondary current with 5 milliseconds of dwell time. On the LS2/truck coil (AC Delco D585), there is 120 milliamps!
We will call the second coil type the LS2/truck coil. These two types of coil have the same connector and pin-out, but the physical mounting pattern is different. The coil connector (GM# 12580353) can be found as:

• Coil Connector Pigtail - small (D581) at www.roblinstores.com, or
• Delphi number: 15439568, which you can order as Mouser 829-15439568

There are plenty of either these coils on eBay, and they often sell for around $22 each at the time this is written.
The LS2 coil has 4 connections (as well as the high tension terminal for the spark plug wire, of course):

• A = Coil Primary Ground
• B = Ignition low noise ground from ECU (ground)
• C = Ignition digital signal from ECU (+5V)
• D = +12V Supply to Coil Primary

The two capacitors are optional but recommended. The 1.0 µF capacitor on the +12V is helpful, it is similar to the one used on EDIS. What it does is provide brief energy storage for the discharge. The other capacitor will help eliminate back-fed noise to the MegaSquirt controller. Use a 100 pF to 0.001 µF cap on the TTL trigger input wire to ground. What this does is shunt extremely fast noise spikes to ground and not let them feed back to the MegaSquirt processor. The added capacitance is minimal - with the series resistance of 1,000 ohms (in the controller) and a 100 pF capacitor the RC 3dB time constant is 2πR × C = 0.6 microseconds.

The LS2 built in coil igniters (the amplifier that drives the coil's primary current based on the sequencer signal) will follow the sequencer signal pulse width. When the signal from the sequencer is high (3 to 5+ Volts - with very little current from the controller, a few dozen milliAmps), the coil current will be building. When the signal from the sequencer is pulled low (shut off), the coil will spark. The duration of the signal from the sequencer determines the dwell (though the coil igniter limits this to no more than ~8 milliseconds).
The maximum dwell should be set at 4.5 milliseconds - going longer does not generate any more spark energy.
To get 4.0 milliseconds of running dwell, the nominal dwell parameters should be set to:

Maximum Dwell
4.5 milliseconds
Maximum Spark Duration
2.0 milliseconds
Acceleration Compensation
0.5 milliseconds
Battery Voltage Compensation
SettingNet VoltageDwell Compensation
-3.0 8.0 Volts 2.4 milliseconds
-1.010.0 Volts 0.9 milliseconds
0.012.0 Volts 0.0 milliseconds
0.514.0 Volts-0.5 milliseconds
1.016.0 Volts-0.9 milliseconds

This will give 4.5 - 0.5 = 4.0 milliseconds at 14.0 volts while running with the alternator charging normally. There is lots more information on setting dwell here: Setting Dwell.
Here is a video of the coil in action - with the LS1 on the test stand you can hear the sparking, not loud but certainly audible. With the LS2/truck coil it sounds like someone is banging on the table!

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