1992 Ford F-150 major electrical problems

Tiny
FORDKING92
  • MEMBER
  • 1992 FORD F-150
  • 5.8L
  • V8
  • 4WD
  • MANUAL
  • 145,000 MILES
Here we go, after a new motor swap ( 4.9l to a 5.8l ). I'm having major electrical issues. My alternator (New) isn't Charging, my power (motor on or off) cycles, meaning it turns on and off by itself hearing a click just before it turns off. And when I turn on the head lights on I lose power to everything else. Turn them off and it comes back on. I've checked every ground I know of and they seem fine. It begain doing this shortly after I rebuilt and reinstalled the transmission. Also the relay in the interior fuse box on the left side of the box is getting very warm during any electrical use. And during the motor swap I found my wires off my alternator were melted all together. Are there any hidden ground wires that I don t know of? I'm lost please help!
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Sunday, May 31st, 2015 AT 6:36 AM

4 Replies

Tiny
HMAC300
  • EXPERT
Ground "B" are most of your grounds for this vehicle including pcm and trans. Unless you have the 165 amp Leece Neville alternator that is how yours is wired. Check the things I've pointed out in pic the grn wires off of starter are fusible links you have one that is either burnt, not connected or is partially making contact. Twirl them around as you check them if they break contact replace it especially how old they are. Also I am assuming that you hooked up all the sensors to the new engine. Make sure you have a ground from battery to engine and engine to body as well as battery to body and they all make contact. If you did the trans and problems started after that check for pinched harness or wire.
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Sunday, May 31st, 2015 AT 8:29 AM
Tiny
FORDKING92
  • MEMBER
Sorry for the delayed reply. I've searched high and low for this ground problem I have, and thanks for the alternator advice. Fixed the problem I was having with charging. Now this electrical flashing problem I have started shortly BEFORE my old motor blew up. Lights fllickering, radio cycling, gauges going crazy, ect. I've looked everywhere I can think of for a bad ground wire somewhere and I can't seem to find it. Are there any INSIDE the cab? Or hidden ones on the frame?

Thanks!
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Wednesday, June 3rd, 2015 AT 7:13 PM
Tiny
HMAC300
  • EXPERT
The flickering of power may be just to abad connection like the junction block at firewall, etc. You might try running a ground wire form engine to body or battery to body. I've sent a pic of ground locations that says where they are. Try the one on cowls and cross members. Cowl Is part in front of windshield
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Thursday, June 4th, 2015 AT 5:55 AM
Tiny
FORDKING92
  • MEMBER
I'm digging into her tonight, I'll let you know the outcome. That pic is amazing Thanks!
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Friday, June 5th, 2015 AT 2:32 PM

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