Electrical question

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So we did a 304 V8 swap in my 84 CJ 7, it had a 4.2 in it, anyway we swapped the motor and even got it to run, but the stereo is trippin, if I turn on the signal light the deck face lights flash with the flasher, does the same thing if you turn the wipers on or the heater, and when its running the deck flashes, but if its turned off the deck works fine, so what do you think?? Bad ground/no ground/ crossed wire?? please help.

[yyc_tbird_sc]

Bad ground. Ground the stereo directly to the frame/body. Also, use a voltmeter and check the voltage to the deck while operating the accessories, see if there is any voltage fluxuations.