At a loss
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At a loss
I’m lost, I have a 86 f150 that has a problem with battery not charging I believe. I have a new alternator, battery, starting solenoid new ground wire. The truck won’t start unless jumped. Once jumped it will fun fine for until I turn it off. Once I turn it off it will not start unless jumped. I can remove my positive terminal and the truck will continue to run. I am at a loss
FTE Legend
Joined: Nov 2015
Posts: 30,898
Likes: 4,119
From: Angier, NC
Welcome to FTE.
First never remove any battery cable when the motor that is a good way to make stuff go bad.
Fully charge the battery before we start looking into what could be going on.
Tell us what you get for volts across the battery with your meter.
When you say "jumped" how are you doing this step by step.
Then we can see what we can find wrong.
BTW is the truck an auto or stick transmission?
Dave ----
First never remove any battery cable when the motor that is a good way to make stuff go bad.
Fully charge the battery before we start looking into what could be going on.
Tell us what you get for volts across the battery with your meter.
When you say "jumped" how are you doing this step by step.
Then we can see what we can find wrong.
BTW is the truck an auto or stick transmission?
Dave ----
Thread Starter
|
New User
Joined: Mar 2020
Posts: 3
Likes: 0
Welcome to FTE.
First never remove any battery cable when the motor that is a good way to make stuff go bad.
Fully charge the battery before we start looking into what could be going on.
Tell us what you get for volts across the battery with your meter.
When you say "jumped" how are you doing this step by step.
Then we can see what we can find wrong.
BTW is the truck an auto or stick transmission?
Dave ----
First never remove any battery cable when the motor that is a good way to make stuff go bad.
Fully charge the battery before we start looking into what could be going on.
Tell us what you get for volts across the battery with your meter.
When you say "jumped" how are you doing this step by step.
Then we can see what we can find wrong.
BTW is the truck an auto or stick transmission?
Dave ----
FTE Legend
Joined: Nov 2015
Posts: 30,898
Likes: 4,119
From: Angier, NC
You posted ok we will not be kicking you off just yet 
So the jumpers go from the other cars battery to your trucks battery and it then starts?
You say you jumped the solenoid how was this done?
Do you get any lights on the dash to come on when the key is turned on?
At first I am thinking bad battery connection.
It would not hurt to clean the connections at the battery and the other ends of the cables.
Or if they have some age on them just replace them as you can not tell if they are bad till you cut them open.
Dave ----
So the jumpers go from the other cars battery to your trucks battery and it then starts?
You say you jumped the solenoid how was this done?
Do you get any lights on the dash to come on when the key is turned on?
At first I am thinking bad battery connection.
It would not hurt to clean the connections at the battery and the other ends of the cables.
Or if they have some age on them just replace them as you can not tell if they are bad till you cut them open.
Dave ----
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Cargo Master
Joined: Jan 2019
Posts: 3,369
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From: Caraway, AR
So, it was a common troubleshooting procedure to remove the positive cable to test the alternator. But that was on pre computer vehicles. The voltage spike can cause damage to sensitive electronics, such as the computers that run vehicles these days. Now when you say bypassed the starter relay, how did you do this? Did you jump the big leads? What about if you jump the ignition terminal on the solenoid to the battery side of the solenoid? You may not be getting power on the start wire from the ignition. But that doesn't fit with you can only start it if you jump it. That would point to a weak battery or bad connections.
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Lead Driver
Joined: Nov 2013
Posts: 7,173
Likes: 1,173
Lots going on here. Lots of good advice, but unfortunately it's all over the place as where to begin troubleshooting. Here's what I recommend:
Charge your battery. This is from Electrical Troubleshooting 101. Don't count on the alternator or a jump start. You'll want a charger with at least a ten amp output, preferably automatic. A trickle charger won't cut it. Hook up the charger overnight.
The next step is to test the control circuit to the starter relay. This is a good place to begin troubleshooting, as this test breaks the entire starter system in half to isolate the fault.
Disconnect the wire from the small S terminal on the starter relay. Connect your meter to check for voltage at the disconnected wire. Key off should be no voltage. Key to run, still no voltage. Turn the key to start and you should now see voltage. Release the key back to run and the voltage should return to zero.
If that tested good, the control circuit to the starter relay is good.
Next step is to put the transmission in neutral (or park if auto) and set the parking brake. Ignition switch to off and remove the key. Stay clear of the drive belts and fan blades as the starter should engage for the next step. Momentarily connect a small test jumper from the battery (+) terminal to the small S terminal on the starter relay (original wire still disconnected). The starter relay should make a big clunk and the starter should engage. This test lead mimics the normal control command from the ignition switch.
Five minutes tops. Try those two quick tests and report back.
Charge your battery. This is from Electrical Troubleshooting 101. Don't count on the alternator or a jump start. You'll want a charger with at least a ten amp output, preferably automatic. A trickle charger won't cut it. Hook up the charger overnight.
The next step is to test the control circuit to the starter relay. This is a good place to begin troubleshooting, as this test breaks the entire starter system in half to isolate the fault.
Disconnect the wire from the small S terminal on the starter relay. Connect your meter to check for voltage at the disconnected wire. Key off should be no voltage. Key to run, still no voltage. Turn the key to start and you should now see voltage. Release the key back to run and the voltage should return to zero.
If that tested good, the control circuit to the starter relay is good.
Next step is to put the transmission in neutral (or park if auto) and set the parking brake. Ignition switch to off and remove the key. Stay clear of the drive belts and fan blades as the starter should engage for the next step. Momentarily connect a small test jumper from the battery (+) terminal to the small S terminal on the starter relay (original wire still disconnected). The starter relay should make a big clunk and the starter should engage. This test lead mimics the normal control command from the ignition switch.
Five minutes tops. Try those two quick tests and report back.
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