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04 Response LXI - Warning beeper DTC42 ignition control.

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I am having a issue with a warning beeper that keeps going off on my 04 Response LXI. Took it in and it threw diagnostic trouble code 42 ignition control. They reset it boat ran great for two weeks and last week took it out to do a some ski runs put it in reverse and warning beeper started to go off again. It use to only go off under load when skiing but now as soon as I engage throttle warning beeper starts up again. When warning signal is going off boat runs rougher and spits and pops at any speed much 20-25mph. Any one ever experience this what was remedy? 

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Code 42 is an ELECTRONIC SPARK TIMING (EST) CIRCUIT trouble code.  So to start check all the wiring that runs from the distributor to the computer.


This circuit triggers the ignition module. The computer does not know what the actual timing is, what it does know is when it gets a reference signal. It uses this reference signal as a base point and advances or retards the spark from that point. So, if on vehicles where the base timing is adjustable, and the base timing is set incorrectly, the spark curve will be off through its entire range by the amount that the base timing is misadjusted. An open or short to ground in this circuit will set the code and cause the engine to run on ignition module timing.
Why the computer flags this code.
What we have here is a failure to communicate. The ignition module and the computer are in constant communication when the engine is in operation. (Over 400 RPM.)With the computer telling the module the correct timing. If communication is lost or a circuit becomes infected with false signals (bad grounds, short to battery +, Electro Magnetic Interference {spark plug wires to close to circuit wiring}, oil contamination of the circuit connectors and wiring) then the computer will turn timing control back to the ignition module and flag the code.
Possible causes:
· EST circuit open or grounded.
· Bypass circuit open or grounded.
· Reference Ground circuit open or shorted to battery +.
· A bad computer to engine circuit ground.
· A defective ignition module.
· A defective computer.

If you are testing a vehicle for this code check the routing of the spark plug wires making sure they are not to close to the EST circuit(s) wiring. Check the connector terminals making sure they are not over-sized or oil contaminated. Check the entire wiring of the circuits for chaffing,
short(s) ground.

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