charging system doesn't
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charging system doesn't
I'm pretty to close to wits end (if not there already). '98 Exp Sport. 4.0L. 2wd.
Alternator has been checked (bench test) and is good, battery is new, belt is good, have continuity from battery neg post to engine ground, have continuity from battery post on alternator to pos battery, 175 Amp link is good,
BUT, I get nothing from the alternator.
EDIT: Oh yeah...before someone jumps on it........engine is running
no difference whether low or high rpm.
knorton
Alternator has been checked (bench test) and is good, battery is new, belt is good, have continuity from battery neg post to engine ground, have continuity from battery post on alternator to pos battery, 175 Amp link is good,
BUT, I get nothing from the alternator.
EDIT: Oh yeah...before someone jumps on it........engine is running
no difference whether low or high rpm.
knorton
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From: Virginia
How to do you know you are getting nothing from the alt? What kind of tests have you run, or are you going by the light in the dash? What kind of voltage readings do you get at the battery with the engine off, and then the engine running?
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I've measured the voltage at the battery both with the engine running and not running. ~12.5 V for each (no change). I measured the current using a clamp on ammeter around the positive bundle at the battery. Slight change as the engine is revved (increase to about 30 amps), but rechecking the battery voltage after this test it had dropped to 11.5 volts, so I assume I was just draining the battery instead of charging.
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I didn't measure actual rpms. Voltage didn't change significantly though from Idle (~900 rpm) which was same voltage as battery with engine off. voltage was
between 12.2 and 12.5. As the engine was running, the voltage was gradually dropping.
between 12.2 and 12.5. As the engine was running, the voltage was gradually dropping.
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From: Alaska
You didn't say how you bench tested the alternator but it is clear that it is not charging, unless you have the tools to test it, take it to your local parts store and they will test it for you,
the battery voltage will decrease as the battery discharges.
the battery voltage will decrease as the battery discharges.
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From: Virginia
One of the guys on here who knows more about the later vehicles, said there was a fuse that Ford added in the fuse box for the field connection on the alternator. I wonder if your vehicle has this fuse?
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From: Lawton, Oklahoma
Here is a schematic of your 98 Explorer charging system... hope this helps.
Franklin I think that particular one you are referring to is for the 97/98 F150 and Expedition. Ford has changed the wiring looms on all the later vehicles about every 2 years unfortuantely, so its very important we have the model and year information these years to give any accurate assistance. Ive been tripped up many times by having the wrong EVTM, even the right year labeled because of mid model year changes. Sometimes I need the exact production date to get it right.
Just to give you a fun example... I recieved a brand new 2004 Expedition last week that had been vandalized at the rail head. Someone had stolen the overhead DVD system and butchered the wiring loom. I needed to order a new wiring loom for the roofline options (DVD, courtesy lamps, domelamps, etc). For that model year there are 24 different harness options just for that section! Sheesh!
Franklin I think that particular one you are referring to is for the 97/98 F150 and Expedition. Ford has changed the wiring looms on all the later vehicles about every 2 years unfortuantely, so its very important we have the model and year information these years to give any accurate assistance. Ive been tripped up many times by having the wrong EVTM, even the right year labeled because of mid model year changes. Sometimes I need the exact production date to get it right.
Just to give you a fun example... I recieved a brand new 2004 Expedition last week that had been vandalized at the rail head. Someone had stolen the overhead DVD system and butchered the wiring loom. I needed to order a new wiring loom for the roofline options (DVD, courtesy lamps, domelamps, etc). For that model year there are 24 different harness options just for that section! Sheesh!
Last edited by HomerWinzlow; Apr 25, 2004 at 07:31 AM.
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From: Virginia
Hey, nice diagram. If I am looking at it right, the black/orange is the output of the alt, and the lightgreen/red brings the alt "online" when the truck is started.
I am assuming the yellow/white is sending the regulator the truck's system voltage info. I see a 30 amp fuse on the yellow/white, and a 7.5 amp on the lightgreen/red. I would check those fuses, and or, make sure you have voltage on the yellow/white and the lightgreen/red when the truck is running.
I am assuming the yellow/white is sending the regulator the truck's system voltage info. I see a 30 amp fuse on the yellow/white, and a 7.5 amp on the lightgreen/red. I would check those fuses, and or, make sure you have voltage on the yellow/white and the lightgreen/red when the truck is running.
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Here's where I am at this point. With the alternator in, ignition on and the engine not running, I measure 12.6 volts at terminals A and B. Zero volts at terminal I. With the engine running......same numbers. Measurements made with plugs attached and measuring through the backside of the plugs. Help!
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From: Virginia
Well, you have obviously zeroed in on the area of the problem. Work your way back up that circuit. The easiest thing would be to find that 7.5 amp fuse and double check it's good, and check for voltage on one of the fuse terminals with the fuse out. After that you have the insturment cluster and it's bulb, plus some other connectors in the harness.
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where is the "S" terminal? My alernator plug has two wires. Y/W and LG/R. There is also the battery terminal, BK/O. Also, the wiring diagram shows the W/BK which I assume is the "S" terminal, and there are three pins in the alternator socket. But, I have only the two wires in the connector.
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From: Lawton, Oklahoma
Is there a separate single pin connector on your alternator? Usually that is where the S terminal is and jumpers the three pin connector to the single pin connector which is usually a grey color.