Charging question

[Zeke Boniface]

2002 Explorer 4.6 FWD 4G alternator Built 7/01

No voltage at alternator plug for I circuit with key in RUN.

I have spent some time online looking for a wiring diagram for the charging system, I have seen some labeled 2002 Explorer, but I have my doubts. CJB, AKA fuse block under dash, fuses 15, 16, 21 have been removed, inspected, and replaced. No effect. Seems like there should be a fuse for I circuit, but I have not found it.

My alternator plug has two wires, lg/rd and or/lb.

Turn key to run, red battery light comes on, turn key to start, battery light goes off a few seconds after engine starts.

Battery voltage at rest, 12.5, voltage running, 12.8, voltage with headlights on, 12.3.

Alternator seems to be doing something, but precious little. But without voltage to turn it on, amazing that it does anything at all. Residual magnetism?

What do I need to do to get voltage to the I circuit?

FWIW, alternator tests fine at local parts store. These folks are my friends.

Thanks,

Zeke B.

 

[imp]

2002 Explorer 4.6 FWD 4G alternator Built 7/01

No voltage at alternator plug for I circuit with key in RUN.

I have spent some time online looking for a wiring diagram for the charging system, I have seen some labeled 2002 Explorer, but I have my doubts. CJB, AKA fuse block under dash, fuses 15, 16, 21 have been removed, inspected, and replaced. No effect. Seems like there should be a fuse for I circuit, but I have not found it.

My alternator plug has two wires, lg/rd and or/lb.

Turn key to run, red battery light comes on, turn key to start, battery light goes off a few seconds after engine starts.

Battery voltage at rest, 12.5, voltage running, 12.8, voltage with headlights on, 12.3.

Alternator seems to be doing something, but precious little. But without voltage to turn it on, amazing that it does anything at all. Residual magnetism?

What do I need to do to get voltage to the I circuit?

FWIW, alternator tests fine at local parts store. These folks are my friends.

Thanks,

Zeke B.

There is indeed a fuse for the I circuit, which leaves the alternator as the lg/rd wire. It goes to the idiot light in the instrument panel. Other side of the light is fed by a 5 amp. fuse; on a 2002 I can't tell you which one, but can say this: if the light illuminates when key is turned ON, the fuse is good, obviously. Since the light goes out upon running, the I circuit is functioning. Something else is limiting alternator output.

The or/lb #14 wire, fairly heavy in comparison, feeds through a fusible link, the other side of which goes to battery + terminal, along with the heaviest wire, bk/og (black/orange) which itself is fused by a fusible link, sometimes 2 in parallel, before connecting to battery +. If any of those fusible links are burnt open, alternator output will be near-zero, or zero. On my 2004, the links are located right behind the battery, where the alternator big wire feeds into the battery junction box (underhood). The links are standard stranded wire downsized and covered with a special silicone insulation which bubbles and gets disfigured if the link burns open. They are not covered within the harness, but are visible for purpose of inspection.

BUT, before going into all this, have the alternator checked by a parts store. If it checks out good, go look at the fuse links, which are a much less likely culprit. The alternator likely has worn out brushes internally. imp

 

[TechGuru]

This diagram is for the 4.0L, I assume it's the same.

You can try replacing just the voltage regulator which includes the brushes.

http://www.rockauto.com/en/moreinfo.php?pk=45730

http://www.rockauto.com/en/moreinfo.php?pk=931205

If you wind up getting a new alternator I'd go with REMY unless you can find a Bosch.

8 Groove Pulley: http://www.rockauto.com/en/moreinfo.php?pk=474230

6 Groove Pulley: http://www.rockauto.com/en/moreinfo.php?pk=1270250

 

[Zeke Boniface]

There is indeed a fuse for the I circuit, which leaves the alternator as the lg/rd wire. It goes to the idiot light in the instrument panel. Other side of the light is fed by a 5 amp. fuse; on a 2002 I can't tell you which one, but can say this: if the light illuminates when key is turned ON, the fuse is good, obviously. Since the light goes out upon running, the I circuit is functioning. Something else is limiting alternator output.

The or/lb #14 wire, fairly heavy in comparison, feeds through a fusible link, the other side of which goes to battery + terminal, along with the heaviest wire, bk/og (black/orange) which itself is fused by a fusible link, sometimes 2 in parallel, before connecting to battery +. If any of those fusible links are burnt open, alternator output will be near-zero, or zero. On my 2004, the links are located right behind the battery, where the alternator big wire feeds into the battery junction box (underhood). The links are standard stranded wire downsized and covered with a special silicone insulation which bubbles and gets disfigured if the link burns open. They are not covered within the harness, but are visible for purpose of inspection.

BUT, before going into all this, have the alternator checked by a parts store. If it checks out good, go look at the fuse links, which are a much less likely culprit. The alternator likely has worn out brushes internally. imp

Thanks imp

I brought my old alternator to the parts store Saturday morning, thinking it would just be a core to trade in on a Remy remanufactured unit. The manager ended up testing both the old alternator and the Remy, and they tested the same. I brought the Remy home just in case, but I can't return it if I install it even as a test, and since I can't come up with the proper input voltage on the I circuit, it could be an expensive test.

The or/lb wire for the A circuit, fortunately, tests good at battery voltage all the time. All wires and links look fine.

Zeke B.

 

[TechGuru]

Buy NEW never REMAN. (also no core needed for new)

This may seem silly but are you sure your belt is not slipping?

What parts store are you having it tested at?

Some like AutoZone and OReilly's have totally automated machines that just give a green light or a red light, good or bad, and do not give any actual test numbers.

A good alternator would be putting out 14.4 volts.

and just because it's putting out 14.4 don't mean it's putting out 14.4 at 130amps like it should be, might only be supplying 1 amp...

 

[TechGuru]

2002 Explorer 4.6 FWD 4G alternator Built 7/01

No voltage at alternator plug for I circuit with key in RUN.

.

What is the voltage on the "I" with it running? I believe the ECU may delay turning the alternator on until after it's running like it does the a/c compressor.

Thing is, the electrical signal on this line should be static and does not regulate the alternator's output voltage, the onboard voltage regulator on the alternator does that.

 

[Zeke Boniface]

This diagram is for the 4.0L, I assume it's the same.

You can try replacing just the voltage regulator which includes the brushes.

http://www.rockauto.com/en/moreinfo.php?pk=45730

http://www.rockauto.com/en/moreinfo.php?pk=931205

If you wind up getting a new alternator I'd go with REMY unless you can find a Bosch.

8 Groove Pulley: http://www.rockauto.com/en/moreinfo.php?pk=474230

6 Groove Pulley: http://www.rockauto.com/en/moreinfo.php?pk=1270250

Thanks TechGuru

I believe that you have provided the real and true wiring diagram. All the colors and numbers match up.

The bad news is, now there are microprocessors and PCM's in the signal path. I had hoped that would not be the case for an early build 2002.

My alternator tested the same as a Remy remanufactured unit at the parts store.

Whether it comes directly from a light bulb or a computer, however, I have to think that the 4G alternator needs to see 11 volts, give or take, to turn on properly. I hate to buy another alternator without providing the proper input first.

Zeke B.

 

[Zeke Boniface]

What is the voltage on the "I" with it running? I believe the ECU may delay turning the alternator on until after it's running like it does the a/c compressor.

Thing is, the electrical signal on this line should be static and does not regulate the alternator's output voltage, the onboard voltage regulator on the alternator does that.

7.7 volts on "I" running, alternator putting out 12.8 volts. That's a lot better than 0 volts on "I" I was getting not running. It might be enough.

I think the tester at the store was an Associated Equipment 8600. It had a digital voltage display and at least four colored lights across the top, and a loose leaf binder telling how to interpret the lights. There was a red light called "alt" that came on when it wasn't supposed to while testing mine, but the reman out of the box tested the same way.

Zeke B.

 

[Zeke Boniface]

Well, find a way to disconnect without perm damage the "I" line while leaving the "A" line connected then run a jumper wire from the battery + terminal to the "I" terminal on the alternator to turn it on and see if you get 14+ volts at the battery.

I'm on it.

To be continued tomorrow.

Thanks,TechGuru

Zeke B.

 

[TechGuru]

I'm on it.

To be continued tomorrow.

Thanks,TechGuru

Zeke B.

Scratch that,

I'm reading that it's normal for the voltage to be lower on that terminal.

Have you verified the B+ line is good?

It sounds like either a regulator problem or the B+ line is faulty.

I have experienced bad alternators testing good at parts stores, and I have read about new reman alternators being bad out of the box.

 

[Zeke Boniface]

I'm reading that it's normal for the voltage to be lower on that terminal.

Have you verified the B+ line is good?

Yeah, I've heard that too. Remy advises 11 or 11.5 as a test voltage. But I wouldn't be surprised if lower than that was OK.

Meter reads battery voltage at the alt B+, everything looks clean and good.

I very much appreciate your input, particularly on the delayed signal. That puts me back on track.

Zeke B.

 

[Zeke Boniface]

Scratch that,

I'm reading that it's normal for the voltage to be lower on that terminal.

Have you verified the B+ line is good?

It sounds like either a regulator problem or the B+ line is faulty.

I have experienced bad alternators testing good at parts stores, and I have read about new reman alternators being bad out of the box.

Remy has a 1-800 tech support number, I was thinking of just calling them and asking what the minimum voltage is to turn on the alternator. But, of course, as you say, the signal is static, the alt is on at 7.7 volts, just not doing very much putting out 12.8. Easy enough to just jumper between B+ and the battery.

 

[TechGuru]

See if anything in this helps.

http://txnj.net/Explorer/2002-03 STARTING & CHARGING SYSTEMS - Generators and Regulators - Explorer & Mountaineer.pdf

Does it still read at B+ with the plug disconnected? I'm trying to find schimattics of the alternator internals, I believe B+ and A and internally linked so if one is good it would make the other look good.

I'm really leaning towards regulator, especially if this is the original alternator, brushes only last so long (and so do bearings) so if it is original I'd replace the whole thing and not just the brushes.

 

[Zeke Boniface]

See if anything in this helps.

http://txnj.net/Explorer/2002-03 STARTING & CHARGING SYSTEMS - Generators and Regulators - Explorer & Mountaineer.pdf

Does it still read at B+ with the plug disconnected? I'm trying to find schimattics of the alternator internals, I believe B+ and A and internally linked so if one is good it would make the other look good.

I'm really leaning towards regulator, especially if this is the original alternator, brushes only last so long (and so do bearings) so if it is original I'd replace the whole thing and not just the brushes.

Yep, it does. From the schematic, it looks like A and B+ go directly to the battery through different wires.

It is the original alternator.

 

[TechGuru]

Just thought I'd throw this out there, have you checked the voltage at 2000 RPM? I had another vehicle that would drain the battery at idle not because the belt was slipping but because the harmonic balancer was slipping.

 

[Zeke Boniface]

Just thought I'd throw this out there, have you checked the voltage at 2000 RPM? I had another vehicle that would drain the battery at idle not because the belt was slipping but because the harmonic balancer was slipping.

I have not checked the voltage above idle, but I will. You've put a lot on my plate for tomorrow, and I appreciate it. I was pretty well stalled most of today. Anxious to get a look at that pdf too.

Hard to imagine anyone being more helpful.

Zeke B.

 

[Joe in NY]

Buy NEW never REMAN. (also no core needed for new)

Sorry but I strongly disagree. New is China. China = JUNK. We just compared side by in the store New "Better" vs Reman. New from china is built to "meet spec" (no standards to meet in china) and re-manufactured is taking an OEM unit (built to higher standards) and replacing the wear and tear items. Diodes, brushes, and bearings.

New:
Sloppy windings with poor coating for heat and vibration protection.
Poor casting of the housing/frame.
China

Reman:
Tighly and neatly wound windings with very nice even coating
Much cleaner casting of the housing/frame
Mexico

The reman also just looked better and less cheesy over all plus it was $20 cheaper.

 

[TechGuru]

Sorry but I STRONGLY disagree. New is China. China = JUNK. We just compared side by in the store New "Better" vs Reman. New from china is built to "meet spec" (no standards to meet in china) and re-manufactured is taking an OEM unit (built to higher standards) and replacing the wear and tear items. Diodes, brushes, and bearings.

New:
Sloppy windings with poor coating for heat and vibration protection.
Poor casting of the housing/frame.
China

Reman:
Tighly and neatly wound windings with very nice even coating
Much cleaner casting of the housing/frame
Mexico

The reman also just looked better and less cheesy over all plus it was $20 cheaper.

Ya maybe for AutoZone Duralast or OReilly Ultima JUNK, not Bosch or Remy.

The problem with reman is not all remanufactures can be trusted. Some shady ones will just wash one, replace the brushes/regulator and sell it.

The only reman I would trust is Bosch and it does not appear to be available for the V8 model, I would just get the current alternator rebuilt by someone local in this case.

Bosch for my Benz, reman in Germany...

 

[TechGuru]

Bosch does make a reman for the V8, the part number is AL7541X, RockAuto is out of stock. SummitRacing would not ship until Sept 25th.

I did find one on EBay: http://www.ebay.com/itm/Alternator-BOSCH-AL7541X-Reman-/292202563466

 

[Zeke Boniface]

2002 Explorer 4.6 FWD 4G alternator Built 7/01

No voltage at alternator plug for I circuit with key in RUN.

I have spent some time online looking for a wiring diagram for the charging system, I have seen some labeled 2002 Explorer, but I have my doubts. CJB, AKA fuse block under dash, fuses 15, 16, 21 have been removed, inspected, and replaced. No effect. Seems like there should be a fuse for I circuit, but I have not found it.

My alternator plug has two wires, lg/rd and or/lb.

Turn key to run, red battery light comes on, turn key to start, battery light goes off a few seconds after engine starts.

Battery voltage at rest, 12.5, voltage running, 12.8, voltage with headlights on, 12.3.

Alternator seems to be doing something, but precious little. But without voltage to turn it on, amazing that it does anything at all. Residual magnetism?

What do I need to do to get voltage to the I circuit?

FWIW, alternator tests fine at local parts store. These folks are my friends.

Thanks,

Zeke B.

May I hijack my own thread for a moment?

Local Craigslist ad for alternator alleged to have been bought "new" from dealer for 2004 truck, truck died shortly thereafter, alternator is for sale for $35. From description, I think it's a 6G.I know, it sounds too good to be true. All that notwithstanding, could it be a replacement for the G4 in my 2002 Explorer?

Thanks, Zeke B.