I have a 1955 chevy truck. the old engine and generator were swapped out with a 1983 350 V8 and 12 vlt alternator. The new electronic ignition module was burned out by the mechanic during installation. the second distributor seemed to go in ok but every since i've been driving the truck the ignition module burns out frequently. do i have a short?

Without testing we'd only be guessing ! You have no idea of the complexity of the electronics on your vehicle . Replacing the ECM would mean a trip back to the dealer to have it programmed . Without programming your vehicle will never start . You had new battery an alternator installed , did it start an run when you picked it up. The charging system on your vehicle is computer controlled . DTC P0621
DTC P0621 : Generator L-Terminal Circuit
The engine control module (ECM) uses the generator turn ON signal circuit to control the load of the generator on the engine. A high side driver in the ECM applies a voltage to the voltage regulator. This signals the voltage regulator to turn the field circuit ON and OFF. The ECM monitors the state of the generator turn ON signal circuit. The ECM should detect low voltage on generator turn on signal circuit when the ignition is ON and the engine is OFF, or when the charging system malfunctions. With the engine running, the ECM should detect high voltage on the generator turn on signal circuit. The ECM performs key ON and RUN tests to determine the status of the generator turn on signal circuit.

Your best bet take it back to the dealer .

Original system has a resistor wire between coil + and ignition key, to reduce voltage and thus increase amps to give fatter spark and increase fuel mileage. For HEI system, this resistor wire must not be used, so run new primary wire straight from switch "run" to coil +. There should already be a wire from the starter solenoid to the coil + to supply full 12 volts when cranking to give higher voltage spark to plugs to help jump the gap better for use while starting. The MSD web site has much more info.

Have your (alternator) Charging system tested ! .This is a computer controlled charging system .
The body control module (BCM) is a class 2 device. It communicates with the powertrain control module (PCM)/engine control module (ECM) and the instrument panel cluster (IPC) for electrical power management (EPM) operation. The BCM determines the output of the generator and sends the information to the PCM/ECM for control of the generator field control circuit. It monitors the generator field duty cycle signal circuit information sent from the PCM/ECM for control of the generator. It monitors a battery current sensor, the battery positive voltage circuit, and estimated battery temperature to determine battery state-of-charge (SOC). The BCM performs idle boost and load management operations.
Powertrain Control Module (PCM)/Engine Control Module (ECM) The PCM/ECM directly controls the generator field control circuit input to the generator. It monitors the generator's generator field duty cycle signal circuit and sends the information to the BCM. The PCM/ECM will override the BCM control of the generator when one of the following conditions is met:
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The engine cooling fans are on high speed.

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There is a high fuel demand.

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The calculated ambient air temperature is less that 0?°C (32?°F).

THE OLD RELYABLE A MATCH BOOK COVER OR ABOUT .017

First, you can't and shouldn't test an alternator by disconnecting the battery cable while the engine is running. You run the risk of cooking the alternator and the computer. Thats how we used to test generators back in the last century.
Is the check engine light on when the engine is running ? Is the battery charge warning light on ?
There should be a fuseable link between the alternator and the battery that could keep the alternator from charging the battery.
The ignition module would have no effect on the charging system.

{: ) It is the engine control module that gives signals to ignition coils . Visually inspect the wirings for the #1 cylinder. But I still suggest that your vehicle be thoroughly scanned to monitor the different parameters and data present on your vehicle.

The ECM or electronic control module does fire the injectors, however, the injector pulse that the control module uses to fire the injectors is generated from the igniton module inside of the distributor and then the injector pulse is processed through the control module.

Most likely the ignition module that is inside of the distributor is faulty, or there is a damaged or grounded wire between the control module and the control unit. If there is no problem to be found with the ignition module inside of the distributor or with the wiring between the control module and the ignition module inside of the distributor, then the problem will be with the electronic control module itself. Also, check all of the fuses to the ECM.

Let me know if you require any further assistance.

if you replace or swap just the power steering motor there is nothing else you need to do,,but if you replace a control module you might need to program it,,,some new module come empty and u need to program it,,,and other ones that are used and u swap it need to be relearn to the car or you might get a check engine light on,,,,for it not being learned by the other modules,,they talk to each other

Need a new battery first, or charge the battery...if the battery is over 3 years old, I would just replace it, also may need a higher output alternator with more amps, to run the electronic fuel injection, fuel pump, and ignition etc...

code 1637 is a generator l circuit code code 300 is a multiple misfire code. from what you are describing i would lean towards wiring problem with alternator circuit.

The L-terminal circuit from the generator is a discrete circuit into the Powertrain Control Module (PCM) . The PCM supplies the ignition voltage to the generator lamp feed. This ignition voltage is pulled low by the generator once the ignition switch supplies ignition 1 voltage . The voltage stays low until the generator turns. When the generator is up and running, the PCM detects ignition voltage. Therefore, with no failures with the vehicles charging system, the lamp terminal circuit will go low 0 volts when the ignition switch is powered up and then goes to the ignition voltage after the engine is started.

I find it hard to believe you need a third alternator. if you do something is going on to burn them up. have them check wires might have a harness rubbed thru grounding out at times