1989 YJ alternator Question - JeepForum.com

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post #1 of 6 Old 08-23-2014, 05:07 PM Thread Starter
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1989 YJ Wrangler 
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1989 YJ alternator Question

So I just completed a HEI conversion because I could not figure out why my old system was not giving spark. But now that the jeep is running I dont think my alternator is charging. I was just wondering does the icm need to be in place for the alternator to charge or can I rip that out. There is also a diode on the white wire out of the alternator that looks like it started to melt. Any way any electrical gurus would be much appreciated!

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post #2 of 6 Old 08-23-2014, 08:39 PM
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1989 YJ Wrangler 
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The diode was to stop the alternator from backfeeding the coil and keeping the coil powered after the ignition was off. The alternator is self regulating so as long as the 12 volts is supplied to the control side your alternator should be supplying power.
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post #3 of 6 Old 08-24-2014, 08:31 AM
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You can check if that diode wire is working properly. It doesnt exactly look like a professional job. Are those solder joints on the ends?
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post #4 of 6 Old 08-24-2014, 10:16 AM
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Hate to disagree with the experts here, but I don't think there is any diode in the charging system.

There is supposed to be a "resistance wire - 15 ohms". It connects between the tan wire on the alt and the yellow wire that connects to the ignition switch and the dash gauge.

I'm looking a the schematic, for a 4.2L, and I don't see any diode in the wiring. All the diodes are internal to the alt.

Dodge did not build my Jeep.
1988 Wrangler,4.2L I-6, Howell EFI JP-1,GM HEI Ign, 5 Speed Peugeot, Zone 2.5" lift + 1/2" booms, BFG 31 x 10.5, Bestop.
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post #5 of 6 Old 08-24-2014, 11:58 AM
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post #6 of 6 Old 08-24-2014, 12:23 PM
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if you search the team rush upgrade, it will explain the need for the diode
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