ground problems
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Senior Member
Joined: Nov 2010
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ground problems
have a problem with a ground on my 87 f150. the alternator is not charging. had the alternator checked 3 times, pretty much have it narrowed down to a ground. can someone help me out on this? would it be the main ground? the one that grounds to the block and the frame? im not an electrician by any means, so need some help. thanks in advance
Senior Member
Joined: Jul 2012
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Can't help but think your best bet would be to track down an electrical diagram for your truck.
You'd think that the best ground for the alternator would be where it bolts up to the block so it makes sense that it would be the main ground cable coming off the battery.
On the other hand ... if that were bad it would never be able to handle the amp draw from the starter when you're firing up the engine ?
Anyway ... it's a simple enough thing to check the battery ground cable. Just follow it down. On mine it bolts to the engine block on two places. It might be different on an 87 though.
You'd think that the best ground for the alternator would be where it bolts up to the block so it makes sense that it would be the main ground cable coming off the battery.
On the other hand ... if that were bad it would never be able to handle the amp draw from the starter when you're firing up the engine ?
Anyway ... it's a simple enough thing to check the battery ground cable. Just follow it down. On mine it bolts to the engine block on two places. It might be different on an 87 though.
Senior Member
Joined: Jun 2011
Posts: 360
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From: North Reading Ma
If you don't have one get a Digital Multi Meter (DMM). The ones for automotive service should run less than than $30, even the ones that go for less will do the job.
The alternator might not be getting the 12v signal to turn on or the feed wire might have an open from the alternator to the battery. Several sites have wiring diagrams and the Haynes manual (for one) has a good trouble shooting procedure that should walk you through it.
If you have an 87 you might have the 2G alternator which is prone to catching fire, consider an upgrade to a 3G and definately examine the wiring harness from the alternator. When my 91 with the 2G failed I installed a JY 95 amp 3G along with some of the 3G harness.
On most of my vehicles I install a ground wire the same size as the main alternator feed from the alternator bracket to the radiator support or direct to the battery.
regards
rikard
The alternator might not be getting the 12v signal to turn on or the feed wire might have an open from the alternator to the battery. Several sites have wiring diagrams and the Haynes manual (for one) has a good trouble shooting procedure that should walk you through it.
If you have an 87 you might have the 2G alternator which is prone to catching fire, consider an upgrade to a 3G and definately examine the wiring harness from the alternator. When my 91 with the 2G failed I installed a JY 95 amp 3G along with some of the 3G harness.
On most of my vehicles I install a ground wire the same size as the main alternator feed from the alternator bracket to the radiator support or direct to the battery.
regards
rikard