Charging system checks
Thread Starter
|
Postmaster
Joined: Mar 2005
Posts: 2,949
Likes: 6
From: Earth
Charging system checks
1986 Bronco with 300 L6 and four speed. It sat for some time before I bought it, so I recently replaced the battery. The starter worked perfectly initially, but after a couple of weeks (it's a weekend driver at best for now...) it got to where it didn't want to crank. Put on new battery cables and a relay and still no joy. Busted out the jumper cables and she cranked right over then roared to life.
Battery shows 12v when sitting, 12v when running, and craters when I try to start. My first thought was to replace the alternator - and I'll probably end up pulling it and having it tested anyway. NAPA has the alternator harnesses and fusible links/wire, so I figure it's worth $18 to ensure the problem isn't there.
Other than that, what else should I check?
And on a related note, could a bad alternator/harness also cause the gauges (other than the tach), brake lights, head lights, etc. not to work?
Thanks.
Battery shows 12v when sitting, 12v when running, and craters when I try to start. My first thought was to replace the alternator - and I'll probably end up pulling it and having it tested anyway. NAPA has the alternator harnesses and fusible links/wire, so I figure it's worth $18 to ensure the problem isn't there.
Other than that, what else should I check?
And on a related note, could a bad alternator/harness also cause the gauges (other than the tach), brake lights, head lights, etc. not to work?
Thanks.
Moderator
Joined: Jan 2001
Posts: 57,025
Likes: 2,756
From: Virginia
12 volts when running means the battery is not being charged. One thing you can try is take a voltmeter or testlight, and make sure you have 12 volts on the large bat output lug on the alternator when the engine is off. If you don't, you probably have a bad fusible link.
Thread Starter
|
Postmaster
Joined: Mar 2005
Posts: 2,949
Likes: 6
From: Earth
The battery definitely needed a charge. The trickle charger was laboring away @ ~10 amps when I first hooked it up. The alternator tested out okay. As I was removing the alternator to have it tested I noticed the belt was looser than it should have been. That may have been the source of my charging problem. A wee bit shorter belt will fix that.
But...
I checked continuity on all the harness wires with a test lamp and they passed. Previous owner had mangled the wiring a bit - the wire going to the choke (white/black) had been cut. Someone just stripped off ~ 1 inch of insulation from the middle of the green/red wire, spliced it in, and taped it up. The green/red wire also had a spot where the insulation had been rubbed through near the alt. harness; the 10 ga. yellow wire to the same harness had a couple of breaks in the insulation as well. I replaced them both, spliced the choke wire back where it belongs and taped the harness back up. Now I just need a couple of days of decent weather to button everything back up.
After removing the power steering belt and A/C belt so I can slip on a new alternator belt, that is. What a pain...
But...
I checked continuity on all the harness wires with a test lamp and they passed. Previous owner had mangled the wiring a bit - the wire going to the choke (white/black) had been cut. Someone just stripped off ~ 1 inch of insulation from the middle of the green/red wire, spliced it in, and taped it up. The green/red wire also had a spot where the insulation had been rubbed through near the alt. harness; the 10 ga. yellow wire to the same harness had a couple of breaks in the insulation as well. I replaced them both, spliced the choke wire back where it belongs and taped the harness back up. Now I just need a couple of days of decent weather to button everything back up.
After removing the power steering belt and A/C belt so I can slip on a new alternator belt, that is. What a pain...
