Charging System
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New User
Joined: Mar 2016
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From: Somewhere in Oregon
Charging System
Hello folks
So, have kind of a weird one...Well, weird to me.
My battery is not charging while the truck is running. Plain and simple...need a new alternator...except...That was the FIRST thing I did after checking that the battery was fine. Battery load tests fine and voltage is good.
Bought a new alternator and it still isn't charging.
My rig is a 1989 F-250 with 5.0L motor. IIRC, voltage reg. is integrated into the alternator. Fusible links all appear to be intact and for the life of my I can not discern the cause.
Any help would be appreciated.
~S
Edit to Add: Also, replaced BOTH battery cables. Starter and Solenoid are also new (Replaced back in January).
So, have kind of a weird one...Well, weird to me.
My battery is not charging while the truck is running. Plain and simple...need a new alternator...except...That was the FIRST thing I did after checking that the battery was fine. Battery load tests fine and voltage is good.
Bought a new alternator and it still isn't charging.
My rig is a 1989 F-250 with 5.0L motor. IIRC, voltage reg. is integrated into the alternator. Fusible links all appear to be intact and for the life of my I can not discern the cause.
Any help would be appreciated.
~S
Edit to Add: Also, replaced BOTH battery cables. Starter and Solenoid are also new (Replaced back in January).
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
When you turn the key to RUN, engine OFF, is the charging system failure warning light on (battery icon)? Your generation of truck MIGHT be different, but with a lot of trucks of this era, that bulb is actually in the circuit that switches on the alternator, and when the bulb goes out, no charge.
Thread Starter
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New User
Joined: Mar 2016
Posts: 13
Likes: 0
From: Somewhere in Oregon
When you turn the key to RUN, engine OFF, is the charging system failure warning light on (battery icon)? Your generation of truck MIGHT be different, but with a lot of trucks of this era, that bulb is actually in the circuit that switches on the alternator, and when the bulb goes out, no charge.
More Turbo
Joined: Jan 2010
Posts: 685
Likes: 1
From: Western NC mountains
On the d shaped plug on alt you need 12v on the yellow wire. This is battery voltage and how the alternator monitors the battery to know what to supply. The green wire red stripe comes from dash to switch on alternator and goes to battery gauge also. Got to have power on both for alternator to charge. White is just stator. The rectangle plug has two black wires with a red stripe (I think red). Those supply power to the battery. I believe those have a fuseable link that could possibly have blown.
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 40
From: EXTREME southwest CT
The charging plug should be replaced any time the generator is serviced, according to Ford's technical service bulletin.
You say the fusible link (s) are good, so I'm going to assume you tested between the charge plug and the 'hot' post of the starter relay.
According to my EVTM there should be a 512 ohm resistor in parallel to the charge indicator lamp, so the alternator should see exciter current even if the bulb itself burns out.
Look on the back of the alternator where the regulator is attached.
One of the screws will have an arrow that says "Ground Here To Test"
With the engine running and a meter connected to monitor system voltage -briefly- ground that screw.
you should see voltage rise up to 17-19
If yes, then the lt grn/red exciter wire is not providing power.
which is near impossible because the bulb lights up, it is grounded through the regulator.
If the system voltage doesn't rise either the charge harness (rectangular plug with two blk/orn 10Ga wires and the wh/Bk stator wire) is bad or the regulator itself is bad.
You say the fusible link (s) are good, so I'm going to assume you tested between the charge plug and the 'hot' post of the starter relay.
According to my EVTM there should be a 512 ohm resistor in parallel to the charge indicator lamp, so the alternator should see exciter current even if the bulb itself burns out.
Look on the back of the alternator where the regulator is attached.
One of the screws will have an arrow that says "Ground Here To Test"
With the engine running and a meter connected to monitor system voltage -briefly- ground that screw.
you should see voltage rise up to 17-19
If yes, then the lt grn/red exciter wire is not providing power.
which is near impossible because the bulb lights up, it is grounded through the regulator.
If the system voltage doesn't rise either the charge harness (rectangular plug with two blk/orn 10Ga wires and the wh/Bk stator wire) is bad or the regulator itself is bad.
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 40
From: EXTREME southwest CT
From Steve83's Supermotors page:
Originally Posted by Steve83
TSB 96-21-04 Generator Harness Connector
Publication Date: OCTOBER 7, 1996
FORD CARS:
1985-90 ESCORT, TEMPO1986 TAURUS1986-90 CROWN VICTORIA1987-92 THUNDERBIRD1987-93 MUSTANGLINCOLN-MERCURY:1985-87 LYNX1985-90 TOPAZ1986 SABLE1986-90 GRAND MARQUIS, TOWN CAR1987-92 COUGAR
LIGHT TRUCK:
1985-90 BRONCO II1985-91 AEROSTAR1986-91 ECONOLINE1986-92 RANGER1986-93 BRONCO1986-94 F-150-350 SERIES . .
ISSUE: When a generator fails, there are a few failure modes that may cause heat to be produced at the wiring harness-to-generator connector. This excess heat may damage the female terminals on the wiring harness, resulting in increased resistance. The increased resistance produces more heat. When the generator is replaced, the resistance produced by a damaged connector may damage the new generator and could result in a repeat repair, including installation of another generator. High resistance (caused by a damaged connector) will not go away until the damaged connector is replaced.
ACTION: Visually inspect the harness-to-generator connector for damage (heat, corrosion, distortion and cracking) before installing a new generator. Install the Generator Wiring Harness Connector Kit (E5AZ-14305-AA) if the harness-to-generator connector is damaged.
The Generator Wiring Harness Connector Kit (E5AZ-14305-AA) contains the following:One (1) Red Wire Butt ConnectorTwo (2) Yellow Wire Butt ConnectorsOne (1) Wire Connector AssemblyOne (1) Instruction Sheet (I.S. 6849)PART NUMBER PART NAME E5AZ-14305-AA Generator Wiring Harness Connector Kit
OTHER APPLICABLE ARTICLES: NONE
SUPERSEDES: 95-25-04
WARRANTY STATUS: INFORMATION ONLY
For other TSBs, check here
-To test the alt, first install a good CHARGED battery. Then momentarily ground the screw on the back of the alt where it says GROUND HERE TO TEST (the Field brush screw) using a jumper wire with the engine at 1500-2500RPM. Have a voltmeter connected across the battery posts. The voltage should instantly spike over 15.5V, and continue to climb slowly. Don't ground that screw for any longer than it takes to make this observation (a couple of seconds). If it fails, the fault could be in the alternator, the wiring, or any connection (including the alt to the block). . .
FORD CARS:
1985-90 ESCORT, TEMPO1986 TAURUS1986-90 CROWN VICTORIA1987-92 THUNDERBIRD1987-93 MUSTANGLINCOLN-MERCURY:1985-87 LYNX1985-90 TOPAZ1986 SABLE1986-90 GRAND MARQUIS, TOWN CAR1987-92 COUGAR
LIGHT TRUCK:
1985-90 BRONCO II1985-91 AEROSTAR1986-91 ECONOLINE1986-92 RANGER1986-93 BRONCO1986-94 F-150-350 SERIES . .
ISSUE: When a generator fails, there are a few failure modes that may cause heat to be produced at the wiring harness-to-generator connector. This excess heat may damage the female terminals on the wiring harness, resulting in increased resistance. The increased resistance produces more heat. When the generator is replaced, the resistance produced by a damaged connector may damage the new generator and could result in a repeat repair, including installation of another generator. High resistance (caused by a damaged connector) will not go away until the damaged connector is replaced.
ACTION: Visually inspect the harness-to-generator connector for damage (heat, corrosion, distortion and cracking) before installing a new generator. Install the Generator Wiring Harness Connector Kit (E5AZ-14305-AA) if the harness-to-generator connector is damaged.
The Generator Wiring Harness Connector Kit (E5AZ-14305-AA) contains the following:One (1) Red Wire Butt ConnectorTwo (2) Yellow Wire Butt ConnectorsOne (1) Wire Connector AssemblyOne (1) Instruction Sheet (I.S. 6849)PART NUMBER PART NAME E5AZ-14305-AA Generator Wiring Harness Connector Kit
OTHER APPLICABLE ARTICLES: NONE
SUPERSEDES: 95-25-04
WARRANTY STATUS: INFORMATION ONLY
For other TSBs, check here
-To test the alt, first install a good CHARGED battery. Then momentarily ground the screw on the back of the alt where it says GROUND HERE TO TEST (the Field brush screw) using a jumper wire with the engine at 1500-2500RPM. Have a voltmeter connected across the battery posts. The voltage should instantly spike over 15.5V, and continue to climb slowly. Don't ground that screw for any longer than it takes to make this observation (a couple of seconds). If it fails, the fault could be in the alternator, the wiring, or any connection (including the alt to the block). . .
Thread Starter
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New User
Joined: Mar 2016
Posts: 13
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From: Somewhere in Oregon
Thanks everyone for the advice. Went back and traced the circuit and found the wire from Alternator to Battery was hooked up incorrectly. That fixed the problem.
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pedant
Joined: Jan 2008
Posts: 23,576
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From: EXTREME southwest CT
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