Weird (to me) electrical issue. Please help!
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Mountain Pass
Joined: Aug 2019
Posts: 161
Likes: 8
Weird (to me) electrical issue. Please help!
1989 F-350 7.3 IDI. I've got what seems (to me) to be a very weird electrical issue. The starter is not turning fast enough to start the truck, acting like the batteries are almost dead. Both of my batteries are fully charged and tested good, the batteries are not the problem. I just replaced the starter with one I know is good, so the starter isn't the issue either. Do I have bad battery cables or battery ground?
People say "check the battery cables" but I don't know what that means. What do I look for? How do I check them? Where are the relevant grounds?
While we're at it, my 1996 F-250 4.9 I6 had a similar issue a few months ago. The starter would click like the battery was dead. I replaced the main battery ground cable that runs from battery-frame-engine with new ends on all of them, and it still wasn't working. The only way I was able to fix it was to run a ground wire straight from the starter to the negative battery post. That doesn't make any sense, though. The starter is attached to the transmission which is connected to the engine. How in the hell could it not be grounded if the engine to frame ground was new and good?
People say "check the battery cables" but I don't know what that means. What do I look for? How do I check them? Where are the relevant grounds?
While we're at it, my 1996 F-250 4.9 I6 had a similar issue a few months ago. The starter would click like the battery was dead. I replaced the main battery ground cable that runs from battery-frame-engine with new ends on all of them, and it still wasn't working. The only way I was able to fix it was to run a ground wire straight from the starter to the negative battery post. That doesn't make any sense, though. The starter is attached to the transmission which is connected to the engine. How in the hell could it not be grounded if the engine to frame ground was new and good?
Fleet Mechanic
Joined: Sep 2016
Posts: 1,519
Likes: 224
From: Nevada
Take a good close look at the cable covering, it may look ok but will have cracks in it.
I changed the ground cable on the drivers side a few months back, mainly because the
end where it clamps to the batt post was in pretty bad shape and all beat to heck. When
got it off and looked at the covering there were small cracks in it from one end to the other.
Bending the cable really opened them up.
Water and salt etc... gets inside and corrodes the copper and cuts down current flow.
This cable was an original from 86.
I had both grounds replaced, and had the cables made at NAPA. They will make any size
and length you need and what ever end you want crimped on. I went with ring terninals
on both ends.
The Engine and trans sits on rubber mounts, so you need a good ground from it to the
Batteries. Just make sure all you connections are clean both pos and neg.
I also up graded the large wire from the Pos Batt post to the Starter and GP Relays to a
larger size.
Both batteries should be same group and CCA size and age. Don`t mix new and old battery
together, old one will weaken the new one by drawing it down.
Charlie
I changed the ground cable on the drivers side a few months back, mainly because the
end where it clamps to the batt post was in pretty bad shape and all beat to heck. When
got it off and looked at the covering there were small cracks in it from one end to the other.
Bending the cable really opened them up.
Water and salt etc... gets inside and corrodes the copper and cuts down current flow.
This cable was an original from 86.
I had both grounds replaced, and had the cables made at NAPA. They will make any size
and length you need and what ever end you want crimped on. I went with ring terninals
on both ends.
The Engine and trans sits on rubber mounts, so you need a good ground from it to the
Batteries. Just make sure all you connections are clean both pos and neg.
I also up graded the large wire from the Pos Batt post to the Starter and GP Relays to a
larger size.
Both batteries should be same group and CCA size and age. Don`t mix new and old battery
together, old one will weaken the new one by drawing it down.
Charlie
More Turbo
Joined: Oct 2009
Posts: 596
Likes: 58
From: West Plains, MO
Of course, look for obvious cracked/broken/overheated spots.
I'm assuming you've already cleaned all four battery posts and the insides of their terminals... and the lug where the positive cable bolts to the starter?
This picture is what I found a few inches from the starter, when I first got my truck...
(I removed the half-melted electrical tape)
Fleet Mechanic
Joined: Jun 2009
Posts: 1,312
Likes: 327
From: San Antonio, TX
Take a good close look at the cable covering, it may look ok but will have cracks in it.
I changed the ground cable on the drivers side a few months back, mainly because the
end where it clamps to the batt post was in pretty bad shape and all beat to heck. When
got it off and looked at the covering there were small cracks in it from one end to the other.
Bending the cable really opened them up.
Water and salt etc... gets inside and corrodes the copper and cuts down current flow.
This cable was an original from 86.
I had both grounds replaced, and had the cables made at NAPA. They will make any size
and length you need and what ever end you want crimped on. I went with ring terninals
on both ends.
The Engine and trans sits on rubber mounts, so you need a good ground from it to the
Batteries. Just make sure all you connections are clean both pos and neg.
I also up graded the large wire from the Pos Batt post to the Starter and GP Relays to a
larger size.
Both batteries should be same group and CCA size and age. Don`t mix new and old battery
together, old one will weaken the new one by drawing it down.
Charlie
I changed the ground cable on the drivers side a few months back, mainly because the
end where it clamps to the batt post was in pretty bad shape and all beat to heck. When
got it off and looked at the covering there were small cracks in it from one end to the other.
Bending the cable really opened them up.
Water and salt etc... gets inside and corrodes the copper and cuts down current flow.
This cable was an original from 86.
I had both grounds replaced, and had the cables made at NAPA. They will make any size
and length you need and what ever end you want crimped on. I went with ring terninals
on both ends.
The Engine and trans sits on rubber mounts, so you need a good ground from it to the
Batteries. Just make sure all you connections are clean both pos and neg.
I also up graded the large wire from the Pos Batt post to the Starter and GP Relays to a
larger size.
Both batteries should be same group and CCA size and age. Don`t mix new and old battery
together, old one will weaken the new one by drawing it down.
Charlie
Start with cleaning all connections.
If problem persists, buy new cables or make some up yourself. It's a good excuse to buy new tools.
I use Ancor tinned wire (protect bare wire with Novalox before crimping) a few sizes up from stock, Ancor lugs, military terminals on the batteries, adhesive lined shrink wrap. I pay attention to what the powerboat community is using; they have to deal with corrosion constantly.
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